The KillerDAC Audio forum
General HIFI => Amplification (Pre/Power) => Topic started by: mcb on October 10, 2010, 05:44:34 PM
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Following the purchase of my ML1’s from Mario earlier this year, I set about rebuilding my system.
At that stage I was running a WFS ST-1000 power amp and a Melody P1688 Signature Pre Amp. The Melody is a great preamp, however the WFS tended to be lean through the midrange. Also, the value of my amps was considerably more than my speakers.
Following advice from a few of the other local guys, the decision was made to sell the WFS and get another tube amp (my initial amp had been an integrated tube amp). A few different things had tweaked my interesting the Ming Da, then I contacted Mike Lenehan to get his comments on various amps. When I raised the Ming Da, Mike advised that they had heard on running with the ML1’s with good results. Following a demo on a different system, I committed to buying one and selling the WFS.
The Ming DA is an EL34 based amp, using 8 x EL34’s to produce 40 watts in triode mode and 75 in ultalinear. The amp is also capable of running as an integrated amp and also a power amp.
My research had indicated that these amps responded well to mods and the first thing to do was to change out the 12AT7’s for something better. Accordingly, I ordered a pair of Brimar CV4024’s and place them in the amp from the start.
Whilst the amp was still new, I tried it with and without the Melody. To my less than acutely attuned ears, the system sounded slightly better with the pre-amp in, however I took the decision to sell the pre and put some of the money towards mods to the amp and the rest towards a standalone dac. The aim being to ultimately develop a better sounding system, for similar overall money.
Soon after buying the amp, a fellow West Aussie posted enquiring about the MingDa and another amp. As a result of the ensuing posts, I learnt that crazikid also had a MC34-AB. Over the ensuing months, I took the opportunity to ask him many questions as to the mods that he had made. Interestingly, crazi was getting guidance from Mario.
As some of you will be aware, flemo has now purchased crazi’s amp (the v8 Ming Da), so it is now not that far away from me.
To date, the changes I have made to my amp are:
i) Changed the 12AT7’s as mentioned above
ii) Changed the 6SN7’s for a pair of RCA BLACK PLATE Smoked Glass NOS 6SN7’s
iii) Changed to the Speaker binding posts for SPC-858M-CU posts from http://www.vt4c.com/shop/program/main.php?cat_id=8&group_id=2&hit_cat=
iv) Changed the power amp RCA’s for RCA-805F-CU also from vt4c.com
v) Disconnected the power amp RCA connectors and relocated one of the other inputs to the new RCA’s. This means that I now use the rear RCA’s as my main connectors and not the side RCA’s.
Changes planned for the future are:
i) Have a case made up to house capacitors
ii) Change out 8 electrolytics for Jensen electrolytics (hopefully these will be shipped in coming week)
iii) Change out 4 capacitors connected to the 12AT7’s and 6SN7’s with bigger capacitors (probably Russian K40Y-9’s)
iv) Bypass the input selector switch, so that all RCA’s other than the rear RCA’s and the selector switch are out of the circuit.
v) Change the stock EL34 valves for Winged C’s
vi) Maybe, change out the 8 capacitors that are connect to the EL34’s
Bottom line, this is a good amp for a modest price and there is plenty of potential to develop it into a very good amp.
I will post a few photo’s once the cap box is built and in place.
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wow. v8 mingda part2.. cant wait. thanks for sharing murray!
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Go for it Murray!!!!
I look forward to tracking your progress for my own future reference. (and selfish reasons)
Cheers
BC
PS. How have you found the changes that you have made so far? You have made a few new ones since i saw you last.
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Go for it Murray!!!!
I look forward to tracking your progress for my own future reference. (and selfish reasons)
Cheers
BC
PS. How have you found the changes that you have made so far? You have made a few new ones since i saw you last.
take your amp to flemo's and compare against the v8 supercharged ming da
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I will wait to be invited i think. ;)
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Hey Murray and Brad,
When my system is up and running and again we'll have to have a mini GTG and compare the stock amp to the V8!
I was very fortunate to purchase James amp so I'm not looking at doing any mod's for a while, if any! I will look at mounting the Jensen cap's underneath the chassis so it's a self contained unit, and maybe add a timber surround to make it look like a more traditional tube amplifier.
Cheers, flemo.
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I will wait to be invited i think. ;)
FLEMO WE NEED A INVITATION for brad so he can get hooked on diy and buy him self a soldering iron(xmass present from wife)
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Sounds good Pete. Ill wait to hear from you.
Other than some input valves mine is stock std and i would like to hear how much difference all the mods make. A fair bit from what iv'e read.
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Go for it Murray!!!!
I look forward to tracking your progress for my own future reference. (and selfish reasons)
Cheers
BC
PS. How have you found the changes that you have made so far? You have made a few new ones since i saw you last.
Hi Brad,
Good to hear from you again.
It will be an interesting project. To be honest, I can't say that I can hear any differences since changing the RCA's and speaker posts, but I have no audio memory, and the least developed ear of all the guys that I have met. If anything, at this stage, I think I my bad soldering is probably more of a handicap than a positive. I will keep practising, but to date, every join that counts has been crap. The practice ones are better. The fact that the "real" soldering is in confined spaces does not help.
When I transferred the RCA location, I had to extend some of the internal wiring. Multiple cable joins is, I am sure, not a good thing. This particular issue will be fixed when I bypass the input switch and other RCA inputs.
Eventually, I will probably get someone else to redo all my soldering, to get the best out of it.
I trust you are still enjoying your Ming Da.
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Hey Murray and Brad,
When my system is up and running and again we'll have to have a mini GTG and compare the stock amp to the V8!
I was very fortunate to purchase James amp so I'm not looking at doing any mod's for a while, if any! I will look at mounting the Jensen cap's underneath the chassis so it's a self contained unit, and maybe add a timber surround to make it look like a more traditional tube amplifier.
Cheers, flemo.
Pete,
I think this would be a very worthwhile exercise. It will give us clear idea or how much the cap mods other EL34's make to the amp. The amps will be running different glass in the front row, though we could fix that quickly.
One other change your "V8" has, that I am not planning on, is that it has a different volume control.
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To be honest, I can't say that I can hear any differences since changing the RCA's and speaker posts, but I have no audio memory, and the least developed ear of all the guys that I have met.
Your audio memory is still better than mine.
Repetition does help a tad here.. i.e. listen to the exact same song over and over and over and over again for several months... Drill that in the head. In time one can probably hear a difference.. As to whether the difference is better or worse, that's too hard for a noob like me :( .
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dont worry about soldering bad murray i still have bad soldering days a solder wick or solder sucker fixes bad soldering joints.
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Go for it Murray!!!!
I look forward to tracking your progress for my own future reference. (and selfish reasons)
Cheers
BC
PS. How have you found the changes that you have made so far? You have made a few new ones since i saw you last.
Hi Brad,
Good to hear from you again.
It will be an interesting project. To be honest, I can't say that I can hear any differences since changing the RCA's and speaker posts, but I have no audio memory, and the least developed ear of all the guys that I have met. If anything, at this stage, I think I my bad soldering is probably more of a handicap than a positive. I will keep practising, but to date, every join that counts has been crap. The practice ones are better. The fact that the "real" soldering is in confined spaces does not help.
When I transferred the RCA location, I had to extend some of the internal wiring. Multiple cable joins is, I am sure, not a good thing. This particular issue will be fixed when I bypass the input switch and other RCA inputs.
Eventually, I will probably get someone else to redo all my soldering, to get the best out of it.
I trust you are still enjoying your Ming Da.
Yes Mate im still happy with mine. Just finished moving house so havent been around much lately but we are in now and my new music room is pretty good.
Dont be too hard on yourself about your soldering. Good to see you having a go mate. I take my hat off to you for that.
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Bottom line, this is a good amp for a modest price and there is plenty of potential to develop it into a very good amp.
bottom line is after mods it wil be hard to beat this amp by commercial offerings available in australia
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Pete,
I think this would be a very worthwhile exercise. It will give us clear idea or how much the cap mods other EL34's make to the amp. The amps will be running different glass in the front row, though we could fix that quickly.
One other change your "V8" has, that I am not planning on, is that it has a different volume control. [/quote]
Hi Murray, I agree mate certainly a worthwhile exercise, and free too so it's all good.
I think the volume pot upgrade could be quite significant with the one James installed, definetly not a cheapie!
Pete
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dont worry about soldering bad murray i still have bad soldering days a solder wick or solder sucker fixes bad soldering joints.
Yes Murray if I can solder then I'm certain you will be able too! Tonight I installed the Obbligato's and Jensen's in the KD, and tidied up the wiring with no drama's at all!! Quite happy about it actually.
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very true flemo the volume pot is a killer takman resistors
http://www.hificollective.co.uk/images/takman_steppedx2l.jpg (the one on the left)
4 volume pots like that in wa that i know off
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wow wow wow bang for your buck amp that is flemo i think you over paid and should pass the amp on to me.
shizer this is amp is a killer chinese special fried rice with a hint of chilli.
man can this baby run the ml1's move over jlti el34 their is a new boss in town and its a killer.
flemo if you ever need money i will take that amp of your hands (less for cash)
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yes.. MD 34 AB is a very good amp.. with the mods - even better!
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Yes I must admit it seems to get better the more I listen to it. It has so much potential for future mod's too. It also has great synergy with the kdac and ML1's. It's well and truly a class above the Yaqin, in fact many amps I have heard!
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the only commercial amp that i have heard which stands up to the mingda special is a vac amp($13,500) no other amp in any retail shop in perth does what this baby can do audio research better do some more researching
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i bought mine direct from mingda.
i reckon its the way to do it. good for our power. in retrospect i would buy again without the stock valves.. get a discount and put the extra cash to svetlana wnged c's and better glass.
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As I have modded my Yaqin as much as I can, after comparing it to flemo's MingDa.. I have to agree with flemo and will say the MingDa is noticably better than the Yaqin. The power is perfect to drive the ML-1s. the bass response is so impressive I actually couldn't believe it and thought flemo had hooked up his subwoofer... what the?!
the amp is perfect match for the ML-1 Ultras ;D
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Murray... you gonna pimp your MD up after hearing flemo's?
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I must admit, I am looking forward to starting the major mods on my amp. Just waiting for clever ideas to house all the caps to be finalised. Then I have to decide if I am brave enough, or get someone to help me. At least the Jensens are in the house.
I have not made up my mind yet regarding the 0.22uf caps for the front row of valves. I am still considering the Russian K40-9's. A couple of other possibilities are the Obbligato Gold Premiums or some Ampohm FE-XAL-AL (if I can find any). Any other thoughts on caps to consider?
I hope Mario gets one and gets serious with the mods. It can only be good for us Ming-Da owners. ;D
Other bit of good news (for me) is that my ML1's are currently with Lenehan Audio, having the Ultra upgrade done.
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Jeez would love to hear the Ming Da in triode mode. I have run my SET 15W amp into the ML1+R and it sounds great but must be using most of the 15W when the wick is turned up. Have a friends Music Reference RM10 EL84 PP amp running at the moment think it is about 35W and F**k me it sounds great. 40W triode mode with a modded Ming Da must be impressive.
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How much is the ultra upgrade costing you Murray?
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How much is the ultra upgrade costing you Murray?
$2000 plus postage
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How much is the ultra upgrade costing you Murray?
$2000 plus postage
what he said!
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its so hard to find a second hand mingda 34ab what is wrong with people its time to upgrade plenty of other amps from china
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http://www.stereo.net.au/forums/showthread.php/29778-FS-Ming-Da-MC-34B-Integrated-Valve-Amp (http://www.stereo.net.au/forums/showthread.php/29778-FS-Ming-Da-MC-34B-Integrated-Valve-Amp)
There ya go Mario. $600 for 2nd hand ming da on SNA. GO GO GO!
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Oops sorry, disregard my previous post. It isn't the same model. Thought it was too good to be true :)
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i would of bought it if it was the one mrs kajak12 would be pissed at me really bad
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After flemo finishing a belly box for my amp last year (same as he built for his amp), I finally started changing the amp caps on the weekend.
Given my lack of experience with these mods and total lack of expertise with a soldering iron, I decided to start with the four caps for the front row of valves.
The good news is that I completed the task, the magic smoke did not escape and the amp still works. Hopefully I will get to change the electrolytics next weekend.
I was going to add some photo's but I keep getting a message that the uploader is full!
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Great work Murray!
Very keen to see the photos :)
"I keep getting a message that the uploader is full!" - Is that an error that the forum page is spitting out at you when you try to upload photo?
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good job murray.. soldering is addictive... :P
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"I keep getting a message that the uploader is full!" - Is that an error that the forum page is spitting out at you when you try to upload photo?
Yep, resized the photos a couple of times, rebooted the laptop and tried reposting a couple of times. Stuffed if I know what the problem is.
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Hey Murray,
Please just use http://www.tinypic.com/ (http://www.tinypic.com/)
Upload the photos and post the 'forum url link'. thats how I do it and tinypic never fails me! :D
Cheers
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Thanks Tuyen,
Lets see if this works
(http://i56.tinypic.com/241vvw5.jpg)
(http://i56.tinypic.com/2h5lmxe.jpg)
(http://i55.tinypic.com/ja8c5j.jpg)
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Jeez thats nice work...very neat, bet it sounds a treat
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Jeez thats nice work...very neat, bet it sounds a treat
Thanks gamve, you will notice there was no close-ups of the soldering ;D. As to sound, I have only had it on for a couple of hours, being fed by the duet, whilst doing other things. I suspect that by the time they settle down, I will have forgotten what it sounded like before. No audio memory.
Once I have finished the changes, Braddles may bring his amp (also a MC34-AB) around. We can then get a good comparison.
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Wow, talk about neatness! Cable tied, heatshrink wrapped connections, caps firmly secured on sticky pads and all!
Nice work mate :) Better job than I could of done thats for sure.
Resistors are an even easier job to replace. Just snip off the stock ones and directly solder on the new ones. No need to fit flyleads, sticky pads, cable ties, etc.
Keen to have a listen to ya setup again, especially now that the mods on the Duet would have been run in (oscon caps, resistors in spdif out etc).
Tuyen
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Thanks for your comments Tuyen.
I look forward to catching up with you again and getting your feedback. I will let you know once the Jensens are in and I have a few hours on them.
Murray
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Yepp I agree with Tuyen, quality work mate. 8)
Keep the pic's going as you continue with the mod's.
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Jeez thats nice work...very neat, bet it sounds a treat
Thanks gamve, you will notice there was no close-ups of the soldering ;D. As to sound, I have only had it on for a couple of hours, being fed by the duet, whilst doing other things. I suspect that by the time they settle down, I will have forgotten what it sounded like before. No audio memory.
Once I have finished the changes, Braddles may bring his amp (also a MC34-AB) around. We can then get a good comparison.
No worrries Murray. Just give me a call when your ready.
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Will do Brad.
I have just added six of the elecytrolytics today, two (the easiest two, I hope) still to go. I have not been brave enough to turn it on. Will leave that until the weekend.
As usual, my soldering has been rather sad. The best join I did all do had to be re-done, as di the run wrong.
One thing with these amps, you need a very hot iron to undo the existing solder connections.
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Following on from my previous posts (albeit, somewhat after the fact), I added the last two electrolytic and then went to start the amp.
Nothing! :(
After some checking, I established that it had eaten the fuse, so I put the spare in. Same result. :( :(
Using a slow blow fuse did not help, so I borrowed flemo’s amp and did a line by line trace. All looked good, so I re did a couple of joints. More blown fuses.
In the end, I gave up and passed my amp onto a local specialist tech. When he was picking the amp up (yes, he picks the gear up and drops it off), I had a good chat with him and learnt a few interesting things. More on this later.
Anyway, once he had seen the amp, he quickly established what was wrong. I had the rectifier (diode array between the two of the caps right at the back of the amp, when in stock form) back to front :o.
Yes people, I now know that diodes, unlike resistors, are directional.
The tech also expressed strong reservations about the various long power cable runs, as these can lead to the voltages becoming unstable. Anyway, he rebuilt the rectifier for me, rearranged the layout a bit with in the belly box and got it going for me again.
He then dropped the amp back the next day. All was good! When he first arrived, he advised that he could not stay, however he then proceeded to take the amp apart, show me what he had done, explain what the thought the shortfalls of the arrangement are and suggested some ideas for improvements.
Following is a picture of the amp as it currently is.
(http://i51.tinypic.com/30m7dis.jpg)
From a purist perspective using tabs to connect to the screw terminals adds another step in the chain, however when multiple connections are required, such tabs are useful. The tabs that were used are Keystone and have part numbers like K906, K918 or similar.
(http://i51.tinypic.com/28jf6lu.jpg)
So was it all worthwhile. Well, when I could not get the amp to start, I was deeply regretting embarking down this road. However, now that it is all finished, the answer is a definite yes ;D. I make no secret about having less than well developed hearing, however the mods have delivered more control, especially in the bass. Braddles may be able to add a little more intelligent feedback, as he bought his unmodded amp around, so that we could compare the two.
I will and a further post, with what caps I used, what I have learnt, and what I would do different if I was to do it again (primarily relates to box construction).
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Following from the earlier post:
What have I learnt (includes comments from the tech)
i) Don’t wire up the rectifier backwards
ii) Fuses do their job. Don’t be tempted to bypass them.
iii) Do not switch between triode and ultralinear on the fly (i.e. turn the amp off, to switch modes)
iv) Do not run the amp without a load on it, including when biasing (i.e. either have the speakers connected up, or dummy loads e.g. 50 watt 8ohm resistors)
v) Use dummy loads or sacrificial speakers, when restarting the amp after mods. Not desirable to destroy expensive speakers (or for those of use with ML1 ultra’s speakers with lots of expensive caps in the crossovers).
vi) Keep cap wiring runs as short a possible, especially in the power caps.
vii) Make sure all caps are securely clamped.
viii) Try to avoid having wiring that moves when the amp is opened up. When the tech took the bottom of my amp to show me what he had done, one of the wires, broke at the solder point. Vigilance is needed when opening and closing amps which have moving wires.
ix) Connecting tabs make life easier.
Other tips
i) Take lots of photo’s before you start pulling things apart.
ii) Make sure you trace all the wiring and record it. When you are trying to back trace, this is invaluable (unless you have a photographic memory).
What would I do differently.
Based on the comments from the tech, I would look to use a sub chassis across the bottom of the amp to mount the electrolytics. Possibly two straps (metal or timber) running from side to side of the bottom of the amp, with the electrolytics clamped directly to them. This means that they are permanently mounted and the wiring does not need to move. Also, the existing wiring probably will not need extending, at least not for the 4 big caps.
Add extension skirts to the sides of the amp (have not figured out the mechanics of this). The four front .22 caps for the front row of valves could then be mounted to the front skirts, once again removing the need for wiring that has to move.
Then a new removable bottom, which fits onto the extended skirts. See rough concept below.
(http://i52.tinypic.com/352oqvl.jpg)
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One more post in this series.
The electrolytics that I have used are Jensens https://audio.jensencapacitors.com/products/capelyt/elytradscr/
Item no. Description Tol. Voltage Dimensions Quantity
020386 47µF -10/+30 500 DC 035x054 1
020391 150µF -10/+30 500 DC 035x070 3
020397 500µF -10/+30 500 DC 050x080 4
edit: these can be bought direct from Jensen or Partsconnexion.
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thanks for all of the information and tips. Great posts and pics......
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Great write up Murray.
DIY is great when it works but so frustrating when things go "POP!" :'(
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Murray, your last few posts great. Really appreciate the effort you put into the well thought-out writeup (loved the dot points)
It's the right attitude to have and show in a great DIY forum like we have here.
Many thanks again and enjoy your modded MingDa (can I come listen to it?? :))
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Thanks for your comments flemo and tuyen.
I have learnt a whole heap from yourselves and others who have been very generous with their time and advice.
Whilst I don't have the depth of knowledge that you guys have, I saw this as an opportunity for me to pass a little bit on.
Tuyen, it would be great to catch up again for a chat and for you to have a listen.
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Great read Murray.
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All good stuff, a good read and glad it is sorted now.
Ming Da do a pretty neato job of their layouts - I had a 34B that I tricked up a little - not as grunty as your beast but pretty sweet sounding and a pretty good headphone out on that too.
Seem to recall a heart stopping moment of blown fuse with that too when I was fooling with it, that was down to a crappy solder joint of my making that I found and sorted. Looked a trifle spectacular before the fuse blew ;P - I'm with you on leaving the fuses alone.
Good write up.
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Thanks for your comment audiophool.
Two more bits of info regarding this amp.
i) The 4 caps used for the front row of valves are Ampohm, Paper in Oil, Aluminium Foil, 630Volt, 0.22uf - CA-PF-XAL-AL-0.22UF-630V. I am not sure if these are available any more.
ii) About a month ago I changed the stock blue EL34 tubes for Gold Lion KT77's. When I first put these in they where a bit harsh on the top end, however they have now settled in nicely and also added control to the bottom end. For those who do not want to change caps, then try changing the main tubes as it is another step in the right direction. Based on the advice of others, I changed the bias point from 0.3v to 0.37v when I changed the valves.
Note: just for clarity the first valves to change are the 12AT7's, then the 6SN7's and then the EL34's.
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Interesting find on the change of power valves murray.
Im a little late but for what its worth murray and i had an interesting afternoon a while back where i bought over my stock mingda (except for upgraded front valves) and my ML1's to compare to murrays modded mingda and upgraded ML1 ultras. I must admit i went over thinking i was a hiding to nothing compareing the two sets but i thought at least i will find out what the next level sounds like. We had a good time going back and forth and at one time or another tried every combo of the 4 components. To cut a long story short i found more difference between the amps than the speakers. The ultras where better than the std ml1's but not 2k worth imo. For a lot less outlay but alot more work the improvement in the amp was more enjoyable and i dare say rewarding for all murrays hard work and patients. I came away from the afternoon with a better understanding of my future upgrade path.
Thanks for the afternoon Murray and for one of the best cups of coffee ive had in a long time.
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Thanks Brad, yes it was an interesting afternoon. I agree, to my ears, the differences between the amps was more significant than the difference between the speakers.
I have noticed over the last month, since the KT77's where added, that the whole system has jelled very nicely. I am thinking that: i) the KT77's have been very worthwhile; and ii) the upgraded crossovers must have also hit the magic number of hours (whatever they may be).
One thing is for certain, the KT77 upgrade is easy, unlike the caps.
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fellow mingda owners its official you can use 5691/6sl7 in your amps,benefit of a larger sound stage :D
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Mario, are any specific 6SL7's that you recommend.
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Mario, are any specific 6SL7's that you recommend.
i have running right now in flemos 5691 black plate rca's
http://www.ebay.com.au/itm/2-NIB-RCA-JAN-CRC-5691-6SL7-Red-Base-Tubes-1-/110686315394?pt=Vintage_Electronics_R2&hash=item19c56b2382
only the ones with WHITE WRITING NOT THE YELLOW WRITING
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since i have flemo's amp on loan i decided to change some wires from the input rca's to the volume pot.WHAT a pain in the arse job 4 hours of fcuking around,wire used is vintage copper carefully cleaned inserted through teflon.the original wire was silver plated multi strand bullsh!t.
the sound is much better smoother not finished yet with this amp more to come.
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Good stuff Mario. :o
I gues with your amp it was pretty much finished and having the Ming Da has given something play with!! 8)
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couple of questions -
first, using the 6SL7. I was reading where the 6SL7 had a MU factor of 70 where the 6SN7 is only 20 - so is it just a plug and play switch and not knowing a whole lot about tubes, it won't hurt anything ?
Second - I am just curious on this one. My amp came from pacific valve. Besides the 4 .22 film caps made by Jinvina or whoever, the rest of the caps in my amp were Multicaps (caps 5, 6, 7 and 8 in mcb's diagram) - were these caps specific to pacific valve or did all MC34AB's come with these ?
Thanks
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couple of questions -
first, using the 6SL7. I was reading where the 6SL7 had a MU factor of 70 where the 6SN7 is only 20 - so is it just a plug and play switch and not knowing a whole lot about tubes, it won't hurt anything ?
Second - I am just curious on this one. My amp came from pacific valve. Besides the 4 .22 film caps made by Jinvina or whoever, the rest of the caps in my amp were Multicaps (caps 5, 6, 7 and 8 in mcb's diagram) - were these caps specific to pacific valve or did all MC34AB's come with these ?
Thanks
i have made no circuit changes to the amp for the 6sl7 its just plug and play working with no problems.regarding the caps in your mingda i have noticed a few pictures on the www of the mingda and they have different caps in them,maybe they changed what caps they use due to cost or supply.
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future changes to be done to flemos mingda
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more future changes to mingda
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the 220k resistor challenge will require a lot of listening
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Great read Mario , now all we need to do is get Pete to decide on A pair of speakers ;D
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Great read Mario , now all we need to do is get Pete to decide on A pair of speakers ;D
he has the ml1's +R ;D
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ok the bias 10r resistors are changed to jay car special 40cents each
yes they are staying much more natural presentation with out the metalic sheen that the metal oxide resistors have.
smoother beautiful but a lot more to go
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my room is a mess working on the amp easy access to the amp is the major factor of quick changes
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Great read Mario , now all we need to do is get Pete to decide on A pair of speakers ;D
he has the ml1's +R ;D
What about some horns in the ht system ;D
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couple of questions -
first, using the 6SL7. I was reading where the 6SL7 had a MU factor of 70 where the 6SN7 is only 20 - so is it just a plug and play switch and not knowing a whole lot about tubes, it won't hurt anything ?
Second - I am just curious on this one. My amp came from pacific valve. Besides the 4 .22 film caps made by Jinvina or whoever, the rest of the caps in my amp were Multicaps (caps 5, 6, 7 and 8 in mcb's diagram) - were these caps specific to pacific valve or did all MC34AB's come with these ?
Thanks
Don,
In my amp, the 4 big caps at the back where EPCOS and the four smaller blue ones are marked BC.
Regards
Murray
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Mario,
Thanks for the posts.
I look forward to reading about more of your findings. Unfortunately, getting down into where some of those resistors and caps reside is well past my capability. I will be interested to read what 1uf caps you use on the EL34's and what their impact is (these look like a real bugger to get at, and if the size is much bigger than the current ones, then mounting will also be a challenge.
I was planning on bypassing all the switches between the input RCA's and volume control, but looks way to daunting for me. I can't even follow all the wiring.
PS With the 10R resistors that you upgraded, would you expect further improvement if you used takman or the like?
Murray
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Mario,
PS With the 10R resistors that you upgraded, would you expect further improvement if you used takman or the like?
Murray
the takman only comes in 1 watt i personally like using 5w for the bias you could get a el34 go troppo and it will blow your bias resistor.So at 40c each for wire wound resistors from jay car is no big deal as to the sound i have no idea
ps:jaycar wire wound resistors is what i use in my amp
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great info. I am going to keep all of my multicaps and just replace the 4 Jinvina .22uf(I have never heard of Jinvina caps). Duelands are out of my price range so will probably just go with the Mundorf silver/oil. Replacing the 10R resistors will also be included.
What I would like to find are some trim pots that are more sturdy or figure out a way to "reinforce" them (some kind of bracket? ). Is not a huge deal, but I would just like to have a little more "heft" when I am in there adjusting the bias. Since you guys are so good at this, I'll hold on until you figure it out ;D
Upgrades for me are sort of on hold now tho as I boat a boat in january and am spending my money getting it fixed up. Probably mid to late summer before i get serious about the upgrades. Gives you plenty of time to find me some better trim pots ;)
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ok the bias 10r resistors are changed to jay car special 40cents each
yes they are staying much more natural presentation with out the metalic sheen that the metal oxide resistors have.
smoother beautiful but a lot more to go
Mario,
10 ohm bias resistors are, IMO kind of dumb!
I always use 1 ohm 1 watt (or 0.5watt) and:
a) you can read mV to mA without any x 10 conversion b) likely to have less impact on sound c)smaller size d) more available types.
cheers
T
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Mario,
PS With the 10R resistors that you upgraded, would you expect further improvement if you used takman or the like?
Murray
the takman only comes in 1 watt i personally like using 5w for the bias you could get a el34 go troppo and it will blow your bias resistor.So at 40c each for wire wound resistors from jay car is no big deal as to the sound i have no idea
ps:jaycar wire wound resistors is what i use in my amp
WRT blowing bias R, that's not a bad thing - it can save your OP transformer.
T
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ok the bias 10r resistors are changed to jay car special 40cents each
yes they are staying much more natural presentation with out the metalic sheen that the metal oxide resistors have.
smoother beautiful but a lot more to go
Mario,
10 ohm bias resistors are, IMO kind of dumb!
I always use 1 ohm 1 watt (or 0.5watt) and:
a) you can read mV to mA without any x 10 conversion b) likely to have less impact on sound c)smaller size d) more available types.
cheers
T
sound very good T with 10r ceramic resistors flemo can play around more with them if he likes
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Mario,
PS With the 10R resistors that you upgraded, would you expect further improvement if you used takman or the like?
Murray
the takman only comes in 1 watt i personally like using 5w for the bias you could get a el34 go troppo and it will blow your bias resistor.So at 40c each for wire wound resistors from jay car is no big deal as to the sound i have no idea
ps:jaycar wire wound resistors is what i use in my amp
WRT blowing bias R, that's not a bad thing - it can save your OP transformer.
T
funny you should say that joe rasmussen said the same thing to me a few years back one day i will try 1w and get back to you regarding sq
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Hi Mario,
Have you made any more progress with Ming-Da mods?
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Hi Mario,
Have you made any more progress with Ming-Da mods?
so far so good mcb more like music compared to when i first got it.
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Flemo's ming da is magical with the right tube combination and parts (caps,resistors,wiring)
Any body reading this in perth if you would like to compare any valve amp up to 15k bring it on the mindgda is ready
ps:flemo you will be one happy chappy
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Any body reading this in perth if you would like to compare any valve amp up to 15k bring it on the mindgda is ready
Is that including your killer EL34 amp? :D
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the el34 killer amp is custom made a bit unfair for the mingda.the 15k mark should apply to commercial amps.i will compare with killer el34 in th future mingda with tube rectification is something that should be looked into.
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Flemo's ming da is magical with the right tube combination and parts (caps,resistors,wiring)
Any body reading this in perth if you would like to compare any valve amp up to 15k bring it on the mindgda is ready
ps:flemo you will be one happy chappy
Good to hear you're still enjoying listening to it and modding it. It will be interesting to hear it in my room once I get my system sorted. 8)
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Flemo's ming da is magical with the right tube combination and parts (caps,resistors,wiring)
Any body reading this in perth if you would like to compare any valve amp up to 15k bring it on the mindgda is ready
ps:flemo you will be one happy chappy
Good to hear you're still enjoying listening to it and modding it. It will be interesting to hear it in my room once I get my system sorted. 8)
who says you getting it back?
have you got any proof its yours?
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Flemo's ming da is magical with the right tube combination and parts (caps,resistors,wiring)
Any body reading this in perth if you would like to compare any valve amp up to 15k bring it on the mindgda is ready
ps:flemo you will be one happy chappy
Good to hear you're still enjoying listening to it and modding it. It will be interesting to hear it in my room once I get my system sorted. 8)
who says you getting it back?
have you got any proof its yours?
Haha funny mate! I think there's a sh*t load of pic's I put on the forum showing a very distinct "dropbox", could be all the proof I need!! :D
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Flemo's ming da is magical with the right tube combination and parts (caps,resistors,wiring)
Any body reading this in perth if you would like to compare any valve amp up to 15k bring it on the mindgda is ready
ps:flemo you will be one happy chappy
Thanks for the update.
It will be interesting to have a listen when (if!) flemo gets it back.
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Another modded Ming-Da, very nice, mcb 8)
Re: Bias resistors.
In my El34 amp i changed from the original wire wound 5w/10r, to 5w/10r Kiwame and found a little less grain in the sound, then I changed them to 2w/10r Kiwame and it sounded a little better again......less constricted maybe?
YMMV as synergy plays a part as we all know :)
Though the move from a 5watter to 2watt was to safe guard the transformers, maybe should go to 1watt?
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Thanks for your comments data and my apologies for the delay in getting back to you. My amp still has the original bi-pass resistors in it. I have bought the wire wound ones that KJ12 linked to, but have not installed them. A bit of a challenge for my dodgy soldering. I am will be getting KJ12, to do some work on mine, to bring it closer to flemo's (remove the input selector, triode/ultralinear switch etc) and will probably get him to put them in at the same time. I have just read flemo's comments on the chokes. I am going to have to hunt down a pair of these chokes. to spec's generally unknown. KJ12, you will have to get back to the guy who built your amp, to see if can advise what they are.
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Thanks for your comments data and my apologies for the delay in getting back to you. My amp still has the original bi-pass resistors in it. I have bought the wire wound ones that KJ12 linked to, but have not installed them. A bit of a challenge for my dodgy soldering. I am will be getting KJ12, to do some work on mine, to bring it closer to flemo's (remove the input selector, triode/ultralinear switch etc) and will probably get him to put them in at the same time. I have just read flemo's comments on the chokes. I am going to have to hunt down a pair of these chokes. to spec's generally unknown. KJ12, you will have to get back to the guy who built your amp, to see if can advise what they are.
Paul had them for years he cant remember anything about them besides being about 10h,mcb speak to earl weston acoustics he make you some chokes to order and also use the wire you specifi
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Another modded Ming-Da, very nice, mcb 8)
Re: Bias resistors.
In my El34 amp i changed from the original wire wound 5w/10r, to 5w/10r Kiwame and found a little less grain in the sound, then I changed them to 2w/10r Kiwame and it sounded a little better again......less constricted maybe?
YMMV as synergy plays a part as we all know :)
Though the move from a 5watter to 2watt was to safe guard the transformers, maybe should go to 1watt?
The mingda had metal film resistors in the bias for el34's,when borrowed flemo's amp i noticed a metalic sheen to the sound so i changed them to wire wound and it was gone i also use them in my amp.I have been also informed about having lower rated resistors for the bias to protect the transformers i will take my chances
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Thanks for your comments data and my apologies for the delay in getting back to you. My amp still has the original bi-pass resistors in it. I have bought the wire wound ones that KJ12 linked to, but have not installed them. A bit of a challenge for my dodgy soldering. I am will be getting KJ12, to do some work on mine, to bring it closer to flemo's (remove the input selector, triode/ultralinear switch etc) and will probably get him to put them in at the same time. I have just read flemo's comments on the chokes. I am going to have to hunt down a pair of these chokes. to spec's generally unknown. KJ12, you will have to get back to the guy who built your amp, to see if can advise what they are.
Paul had them for years he cant remember anything about them besides being about 10h,mcb speak to earl weston acoustics he make you some chokes to order and also use the wire you specifi
Thanks for the tip KJ12.
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Murry is it?
I'm just wondering about the improvement from the Ampohm aluminum foil & oil caps?
They are coupling the first two stages, are they not? hmm..three stage amp huh?
Just wondering what they are like, what they sound like? :)
Also, what (1uf) caps are you using between the second and final stages ?
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Thanks for your comments data and my apologies for the delay in getting back to you. My amp still has the original bi-pass resistors in it. I have bought the wire wound ones that KJ12 linked to, but have not installed them. A bit of a challenge for my dodgy soldering. I am will be getting KJ12, to do some work on mine, to bring it closer to flemo's (remove the input selector, triode/ultralinear switch etc) and will probably get him to put them in at the same time. I have just read flemo's comments on the chokes. I am going to have to hunt down a pair of these chokes. to spec's generally unknown. KJ12, you will have to get back to the guy who built your amp, to see if can advise what they are.
Paul had them for years he cant remember anything about them besides being about 10h,mcb speak to earl weston acoustics he make you some chokes to order and also use the wire you specifi
Does anyone have an LCR meter? I'm looking to buy one but it seems that Jaycar does not have it anymore, suggestion please?
Thanks,
William
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RS have them.
http://australia.rs-online.com/web/p/products/6659857/
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Thanks data, I found another one which is cheaper: http://www.techtronics.com.au/p/104817/TEST_EQUIPMENT_MULTIMETERS/NoBrand/Q1156.asp
The Agilent looks better and more reliable though...
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A lot! cheaper, nice :)
You might be right, one thing I have found with a normal multimeter, is that the cheaper ones are very hit & miss with some readings, particularly when measuring things in-circuit :(
Although the LCR meter you linked is neither dirt cheap, nor crazy expensive so might be fine 8)
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Yeah I agree, it's hit and miss. I'll get one soon and hopefully it works well. Cheers.
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Murry is it?
I'm just wondering about the improvement from the Ampohm aluminum foil & oil caps?
They are coupling the first two stages, are they not? hmm..three stage amp huh?
Just wondering what they are like, what they sound like? :)
Also, what (1uf) caps are you using between the second and final stages ?
Hi Data, my knowledge of the technicalities of amps is near non-existent. All my mods have been based on proven mods made by others, primarily those initially made by crazikid, to the amp now owned by flemo. This means I can't comment on first stage, second stage etc. Also, I am not too flash at describing what I hear (and I am not a critical listener). I basically like the change or I don't. To that end, the adding the 0.22 ampohms, was a good step forward. How they sound, compared to other caps, I can't comment on. Also, ampohms are now fairly hard to get, though i have not checked their availability for a while.
As to the 1 uf caps, if you are referring to the white ones that are commented on by Mario at post 66 of this thread, then, mine are still the original MingDa caps. Way to fiddly for me to get down into there.
Regard
Murray
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Yeah I'm not all that knowledgeable myself compared to many.
Thanks for the comment of how much better it sounds now, says a lot for the caps :)
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.... annnnnnddd, as of this afternoon, mcb's amp is going to be rab's amp! ;D I will be collecting it in person on Feb 6 or thereabouts! Can't wait! ;D ;D
The plan will be to continue mcb's project to replicate flemo's mods and hopefully bring it to the same level (sadly, without flemo's skirt bling).
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.... annnnnnddd, as of this afternoon, mcb's amp is going to be rab's amp! ;D I will be collecting it in person on Feb 6 or thereabouts! Can't wait! ;D ;D
Carry on hand luggage? :p
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.... annnnnnddd, as of this afternoon, mcb's amp is going to be rab's amp! ;D I will be collecting it in person on Feb 6 or thereabouts! Can't wait! ;D ;D
The plan will be to continue mcb's project to replicate flemo's mods and hopefully bring it to the same level (sadly, without flemo's skirt bling).
I am looking forward to meeting you in a couple of weeks rab. Your post in the other thread last week was indeed very timely.
New amps for both of us, though the changes for one of us is not quite as big as for the other.
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.... annnnnnddd, as of this afternoon, mcb's amp is going to be rab's amp! ;D I will be collecting it in person on Feb 6 or thereabouts! Can't wait! ;D ;D
Carry on hand luggage? :p
Only if he as spent a lot of hours in the gym :o
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Only if he as sent a lot of hours in the gym :o
Two weeks to train.. :) IIRC this amp is pretty heavy. So what new amp are you getting?
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:) ;) :D ;D
Incidentally, I just saw on the weekend for the first time that a US company has commissioned MingDa to make a souped up version they call the MD75 for the US market - or at least are the exclusive dealer. There is an upgrade version running KT88's! Does that mean we can run KT88's in our 'standard' versions with appropriate bias adjustment, or is more required?
http://www.pacificvalve.us/MingDaMD75.html (http://www.pacificvalve.us/MingDaMD75.html).
Close-up of the innards is here:
http://www.pacificvalve.us/images/_DSC4118.jpg (http://www.pacificvalve.us/images/_DSC4118.jpg)
One nice feature in the new version is the provision of bias adjustment trimpots accessible from the top of the amp - through RCA female sockets!
See here: http://www.hometheaterhifi.com/integrated-amplifiers/1447-ming-da-md-75-integrated-stereo-tube-amplifier.html?start=1 (http://www.hometheaterhifi.com/integrated-amplifiers/1447-ming-da-md-75-integrated-stereo-tube-amplifier.html?start=1).
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To run KT88's I think the only thing ya' need to change is the filament current....but even that may be OK, you would need to check.
Running KT88's will just change the sound, no extra power to be had running in the same amp.
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Thanks, data. I confess i have no idea how these different valves would change the sound. flemo is running SED Winged C's, mcb has been running Genelex KT77's,... at this stage I have yet to decide what valves to buy... I have some bias towards the Winged C's because the reports of flemo's amp are so positive, and the cost for a matched quad is only A$150 delivered (http://thetubestore.com/el341.html).
Any opinions?
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I know folk that prefer the sound of KT88's but for myself I like the EL34's, and so far my preference is for the Winged C's also.
KT88's have a cleaner, less warm sound compared to EL34's.
I suck at describing the sound of things ::)
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Thanks, data. I confess i have no idea how these different valves would change the sound. flemo is running SED Winged C's, mcb has been running Genelex KT77's,... at this stage I have yet to decide what valves to buy... I have some bias towards the Winged C's because the reports of flemo's amp are so positive, and the cost for a matched quad is only A$150 delivered (http://thetubestore.com/el341.html).
Any opinions?
The mingda your buying is made for el34 tubes others will work but not to full potential stick with el34 (svetlana el34 winged c) or the big bucks el34 philips double dd getter
)
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ah, i was wondering when you would show up...! ;)
thanks, Mario - sounds like i should buy those SED valves.
What would you recommend for the other (small) valves?
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I know folk that prefer the sound of KT88's but for myself I like the EL34's, and so far my preference is for the Winged C's also.
KT88's have a cleaner, less warm sound compared to EL34's.
I suck at describing the sound of things ::)
One thing that hasn't been mentioned here is that despite the KT88 offering little more absolute max power, they can be biased much higher.
KT88's have a max anode dissipation of 42W so for a 500V HT and a 75% of max dissipation bias point, you will get much higher class A operation.
So the short of it is just changing tubes is one thing, but finding their best bias / operating point is another.
IME, plenty of bias for KT's is a good thing and they can handle it.
Same goes for 6L6's. I've been using JJ's, which are not the worlds best sounding tubes, but you can bias them to >40mA easily and it really helps the sound.
EL34's tend to be less robust and can be more finicky about bias. I think this might be the Pentode versus Beam Power construction - they are very different tubes.
T
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Thanks, Terry. Interesting, but do you have an opinion on the relative sound quality of the two?
Incidentally, this may be a dumb question, but are the 6SN7 and 12AT7 valves only used in the preamp section? The reason i ask is that i will mainly use this (at least initially) with my PDX DAC which has an SRPP output stage and a built-in lightspeed-type attenuator, so I could use the MingDa either with or without the preamp section... i suspect without the preamp may be better... has anyone done a similar comparison?
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Thanks, Terry. Interesting, but do you have an opinion on the relative sound quality of the two?
IME both tubes can sound fantastic, it depends on circuit / bias / brand.
I've had amps come through for repair with both with great variance.
If I were to make a huge generalization which I hate to do
EL = more complex harmonics, sweet midrange
KT = bigger / cleaner
For hifi, I think if circuit is optimized, KT's are a great tube but much harder to get right.
[/quote]
Incidentally, this may be a dumb question, but are the 6SN7 and 12AT7 valves only used in the preamp section? The reason i ask is that i will mainly use this (at least initially) with my PDX DAC which has an SRPP output stage and a built-in lightspeed-type attenuator, so I could use the MingDa either with or without the preamp section... i suspect without the preamp may be better... has anyone done a similar comparison?
[/quote]
AFAIK, you need all the tubes in your Mingda
cheers
T
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Thanks, Terry. Interesting, but do you have an opinion on the relative sound quality of the two?
Incidentally, this may be a dumb question, but are the 6SN7 and 12AT7 valves only used in the preamp section? The reason i ask is that i will mainly use this (at least initially) with my PDX DAC which has an SRPP output stage and a built-in lightspeed-type attenuator, so I could use the MingDa either with or without the preamp section... i suspect without the preamp may be better... has anyone done a similar comparison?
Mr.Rab the mingda runs a whole lot better using the integrated mode due to the way its wired up just for amplification duties,all of this can get changed i can tell you how to do it.You will have a handful of parts left over i know that mcb's amp is good much more needed to make it great.
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Thanks T and Mario.
It sounds like i should stick to the SED Winged C EL34's.
Incidentally, at http://www.tubedepot.com/sv-el34.html (http://www.tubedepot.com/sv-el34.html) it seems i can get an octet delivered FedeX for A$300. Similar price at http://thetubestore.com/el341.html (http://thetubestore.com/el341.html).
Has anyone had good or bad experiences with either of these sites?
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Only if he as sent a lot of hours in the gym :o
Two weeks to train.. :) IIRC this amp is pretty heavy. So what new amp are you getting?
Hi Treblid,
I have bought flemo's MingDa :D.
We (flemo & I) started talking about it a few days before rab made his timely post about looking for one,
thus a good arrangement for all of us.
The other good thing for rab is that he will get to hear the difference between the two and what the next round of upgrades will deliver.
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Hi Treblid,
I have bought flemo's MingDa :D.
We (flemo & I) started talking about it a few days before rab made his timely post about looking for one,
thus a good arrangement for all of us.
The other good thing for rab is that he will get to hear the difference between the two and what the next round of upgrades will deliver.
LOL... The stars align so to speak.. Congrats to all ^_^...
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Struth Bruce.
Trying to change a Ford Escort into a Jaguar is going to be difficult at best and rearly works, you might be better buying the sound you want rather than blowing more money in trying to get the different valves to work in a circuit that was not designed for them. This to my knowledge has only been pulled off once and it was with a Quad 2, I'll say that again ONCE it's only been done once by a batty old proffesor type who ended up in the nut house and knew intamately the in's and out's of valve design, he even had his own circle of listening cat's (the 70's term for the mondern 'Dude' ) and did not market until everyone said yes. With all the tuning effort of Mario into geting the device sounding musical it's easily upset by changes. Oh well, yer pays your money and makes your choice.
Best of luck and remember, tech's in Perth are REALLY expensive when bias and B+ currents draw more than the original design and the magic smoke rises.
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Struth Bruce.
Trying to change a Ford Escort into a Jaguar is going to be difficult at best and rearly works, you might be better buying the sound you want rather than blowing more money in trying to get the different valves to work in a circuit that was not designed for them. This to my knowledge has only been pulled off once and it was with a Quad 2, I'll say that again ONCE it's only been done once by a batty old proffesor type who ended up in the nut house and knew intamately the in's and out's of valve design, he even had his own circle of listening cat's (the 70's term for the mondern 'Dude' ) and did not market until everyone said yes. With all the tuning effort of Mario into geting the device sounding musical it's easily upset by changes. Oh well, yer pays your money and makes your choice.
Best of luck and remember, tech's in Perth are REALLY expensive when bias and B+ currents draw more than the original design and the magic smoke rises.
hey dude flemo's mingda tested by a perth tech ultra stable after kajak12 modds :P :P lucky punt i guess
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Yepp MCB's amp was tested and measured before it changed ownership.
The tests revealed the tubes were barely stressed and the amp worked effortlessly. All the tubes tested as almost brand new, and the EL34's could be 2 years old.
The techie commented on how well the amp functioned and sounded, and would easily out perform many hi-end, more expensive amplifiers. I was happy with the techies findings because it was quite expensive to confirm what some of us already knew. ???
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blowing more money in trying to get the different valves to work in a circuit that was not designed for them.
? huh ? -- not sure what you are on about vv-dude. mcb has been using KT77's, which i understand is a commonly used drop-in replacement for the EL34.
As for me, as indicated in earlier posts I have followed flemos' lead and opted for Winged C EL34's - I ordered an octet yesterday and they are already on their way to me from the USA via FedEx.
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;D Easy really Rab, the whole amp would have been tuned around EL34's, by changing the valves the balance will be changed. Kinkless Tetrodes are differnet in more ways than having the same pin outs but you will have to discover this for yourself. IMV the EL34 has a denser sound with bold broad stroke colour palette, the KT's have a more delicate sound with a finer delinated colour palette. You makes your choices. Have you considered the 6550's as well? These sound more muscular than either but it would be a yankie jobbie biggest - boldest approach. ;D
I would think that some of the more experianced valve heads here can chip in but as this is a personal prefference thing you pays your money and hope to receive a good set of valves. I was not suggesting that the valve swap would not work, only that the sound and balence from top to bottom would change. ;D ;D
V ;)
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by changing the valves the balance will be changed.
... sure; i was just confused by your post because i am sticking to EL34's which, as you know, the amp was designed to use... so I suppose your comments are more relevant to mcb, who is using KT77's...
- r.
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by changing the valves the balance will be changed.
... sure; i was just confused by your post because i am sticking to EL34's which, as you know, the amp was designed to use... so I suppose your comments are more relevant to mcb, who is using KT77's...
- r.
Hey, no worries. I will try to be clearer in future.
V
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[ Winged C EL34's - I ordered an octet yesterday and they are already on their way to me from the USA via FedEx.
... and just arrived, apparently in good order, as 2 matched quartets (4 x 40 and 4 x 39 mA).
Not bad, 5 days from placing the order to final delivery! Thank you Tube Depot and FedEx!
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[ Winged C EL34's - I ordered an octet yesterday and they are already on their way to me from the USA via FedEx.
... and just arrived, apparently in good order, as 2 matched quartets (4 x 40 and 4 x 39 mA).
Not bad, 5 days from placing the order to final delivery! Thank you Tube Depot and FedEx!
;D Wow, 5 days from overseas, Oz post could learn a thing or two from fedex, I usually have to wait at least 10 days to have things arrive from the Eastern states.
Enjoy V
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Then there are things nationally that never show up, bloody Aus Post >:(
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[ Winged C EL34's - I ordered an octet yesterday and they are already on their way to me from the USA via FedEx.
... and just arrived, apparently in good order, as 2 matched quartets (4 x 40 and 4 x 39 mA).
Not bad, 5 days from placing the order to final delivery! Thank you Tube Depot and FedEx!
bring them with you i will test them and show you that matched tubes are just a marketing bullsh!!t,The mingda is manual biasing so no need for matched tubes food for thought.
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[ Winged C EL34's - I ordered an octet yesterday and they are already on their way to me from the USA via FedEx.
... and just arrived, apparently in good order, as 2 matched quartets (4 x 40 and 4 x 39 mA).
Not bad, 5 days from placing the order to final delivery! Thank you Tube Depot and FedEx!
bring them with you i will test them and show you that matched tubes are just a marketing bullsh!!t,The mingda is manual biasing so no need for matched tubes food for thought.
Interesting Mario, they will always make a case for charging more for a matched quad etc so if this is a ploy discovered by actual testing then the various sellors need to be called to book. :o :o :o :o :o
Let us all know the actual readings from the tests please.
V ;D
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Then there are things nationally that never show up, bloody Aus Post >:(
Can't do much data, not too mention poor handling by ANY courier in the world. Registered/trackable mail is an option but it's a LOT more expensive. Bought two RCA UX-250 globes from the US, one seller charged $12 (untrackable and uninsured) and the other seller charged $45 (trackable and insured)!!!
[ Winged C EL34's - I ordered an octet yesterday and they are already on their way to me from the USA via FedEx.
... and just arrived, apparently in good order, as 2 matched quartets (4 x 40 and 4 x 39 mA).
Not bad, 5 days from placing the order to final delivery! Thank you Tube Depot and FedEx!
;D Wow, 5 days from overseas, Oz post could learn a thing or two from fedex, I usually have to wait at least 10 days to have things arrive from the Eastern states.
Enjoy V
Agree, it's very quick, how much did you pay for the shipping rab?
Cheers,
William
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Then there are things nationally that never show up, bloody Aus Post >:(
Can't do much data, not too mention poor handling by ANY courier in the world. Registered/trackable mail is an option but it's a LOT more expensive. Bought two RCA UX-250 globes from the US, one seller charged $12 (untrackable and uninsured) and the other seller charged $45 (trackable and insured)!!!
Cheers,
William
Very true, and as for couriers, I'm not going there......damn Toll! ::)
Ooops! I went there :D
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how much did you pay for the shipping rab?
US$34.95 fixed price for FedEx shipping. The other site may have been cheaper for slower delivery (they estimate ~ US$20 for 4 EL34s), but i just wanted to get them here.
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bring them with you i will test them and show you that matched tubes are just a marketing bullsh!!t
...they will always make a case for charging more for a matched quad etc...
Let us all know the actual readings from the tests please.
Tube Depot do not charge any extra for matching, they just do it automatically when you order multiples.
I would be extremely surprised if it is false given my positive experiences of North American service standards! Sorry Mario and VVD, but it's too much hassle to fly these tubes across the country twice just to confirm this...
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bring them with you i will test them and show you that matched tubes are just a marketing bullsh!!t
...they will always make a case for charging more for a matched quad etc...
Let us all know the actual readings from the tests please.
Tube Depot do not charge any extra for matching, they just do it automatically when you order multiples.
I would be extremely surprised if it is false given my positive experiences of North American service standards! Sorry Mario and VVD, but it's too much hassle to fly these tubes across the country twice just to confirm this...
Tube depot oh i have some tubes from them rab the problem was when i measured them they where not very stable in fact 3 out of 8 where unstable should have been binned not sold.
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[ Winged C EL34's - I ordered an octet yesterday and they are already on their way to me from the USA via FedEx.
... and just arrived, apparently in good order, as 2 matched quartets (4 x 40 and 4 x 39 mA).
Not bad, 5 days from placing the order to final delivery! Thank you Tube Depot and FedEx!
bring them with you i will test them and show you that matched tubes are just a marketing bullsh!!t,The mingda is manual biasing so no need for matched tubes food for thought.
Interesting Mario, they will always make a case for charging more for a matched quad etc so if this is a ploy discovered by actual testing then the various sellors need to be called to book. :o :o :o :o :o
Let us all know the actual readings from the tests please.
V ;D
Vita, some clarifications are in order. :)
Tubes are burned in for 2 main reasons:
a) To stabilize them. Parameters drift over time but the biggest change is initially when first 'fired up' and then they slow down.
b) Weed out the 'infant mortality' rate'. IOW, if they are going to fail it is usually early in the life span.
They are matched for 2 parameters, a) current at a certain grid voltage (bias) and b) transconductance
I think burned in / matched tubes do sound better and it's a good idea from a reliability POV.
I've got boxes of (un burned in) tubes that failed just after new. Very frustrating.
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[ Winged C EL34's - I ordered an octet yesterday and they are already on their way to me from the USA via FedEx.
... and just arrived, apparently in good order, as 2 matched quartets (4 x 40 and 4 x 39 mA).
Not bad, 5 days from placing the order to final delivery! Thank you Tube Depot and FedEx!
bring them with you i will test them and show you that matched tubes are just a marketing bullsh!!t,The mingda is manual biasing so no need for matched tubes food for thought.
Interesting Mario, they will always make a case for charging more for a matched quad etc so if this is a ploy discovered by actual testing then the various sellors need to be called to book. :o :o :o :o :o
Let us all know the actual readings from the tests please.
V ;D
Vita, some clarifications are in order. :)
Tubes are burned in for 2 main reasons:
a) To stabilize them. Parameters drift over time but the biggest change is initially when first 'fired up' and then they slow down.
b) Weed out the 'infant mortality' rate'. IOW, if they are going to fail it is usually early in the life span.
They are matched for 2 parameters, a) current at a certain grid voltage (bias) and b) transconductance
I think burned in / matched tubes do sound better and it's a good idea from a reliability POV.
I've got boxes of (un burned in) tubes that failed just after new. Very frustrating.
Yup familiar with this as have own valve tester Mr. T ;D although it's not as good as Mario's. :( Still a way to try and calm the public and make out that they are above the madding crowd. ::) Groove Tubes are the only company I know who burn in the valves properly before grading them and reselling them on, do you really think everyone 'burns in the tubes' before measuring them for sale??? ??? I would like thier contact details to avoid boxes of failed valves!
Any sign of a crystal finding a home in WA??? :-* :-* :-* :-* :-*
V
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Tube depot oh i have some tubes from them rab the problem was when i measured them they where not very stable in fact 3 out of 8 where unstable should have been binned not sold.
OK, now you are making me nervous. Beyond just curiosity, it is actually a good idea that i bring them to check they are OK?
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[ Winged C EL34's - I ordered an octet yesterday and they are already on their way to me from the USA via FedEx.
... and just arrived, apparently in good order, as 2 matched quartets (4 x 40 and 4 x 39 mA).
Not bad, 5 days from placing the order to final delivery! Thank you Tube Depot and FedEx!
bring them with you i will test them and show you that matched tubes are just a marketing bullsh!!t,The mingda is manual biasing so no need for matched tubes food for thought.
Interesting Mario, they will always make a case for charging more for a matched quad etc so if this is a ploy discovered by actual testing then the various sellors need to be called to book. :o :o :o :o :o
Let us all know the actual readings from the tests please.
V ;D
Vita, some clarifications are in order. :)
Tubes are burned in for 2 main reasons:
a) To stabilize them. Parameters drift over time but the biggest change is initially when first 'fired up' and then they slow down.
b) Weed out the 'infant mortality' rate'. IOW, if they are going to fail it is usually early in the life span.
They are matched for 2 parameters, a) current at a certain grid voltage (bias) and b) transconductance
I think burned in / matched tubes do sound better and it's a good idea from a reliability POV.
I've got boxes of (un burned in) tubes that failed just after new. Very frustrating.
Yup familiar with this as have own valve tester Mr. T ;D although it's not as good as Mario's. :(
Then you understand what 'gm' means and why they are matched for both IP current -and- gm? So why are we having this conversation?
Still a way to try and calm the public and make out that they are above the madding crowd. ::) Groove Tubes are the only company I know who burn in the valves properly before grading them and reselling them on, do you really think everyone 'burns in the tubes' before measuring them for sale??? ??? I would like thier contact details to avoid boxes of failed valves!
Vita, I get my tubes from the distriubutors / manufacturers, same place tubedepot would.
The distributors and manufacturers generally do the 24hr burn in and matching. If the tubes are faulty / unmatched / drfiting in bias, they should be sent back to TD for a refund.
IME, good tubes that are burnt in / matched are very stable with bias and usually very close to each other.
Mario, what exactly were they doing, you say 'unstable'? They might even be oscillating which can look like a fluctuating DC current with an ohm meter. You need to get a cro if you
are doing this sort of stuff on a regular basis.
cheers
T
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Tube depot oh i have some tubes from them rab the problem was when i measured them they where not very stable in fact 3 out of 8 where unstable should have been binned not sold.
OK, now you are making me nervous. Beyond just curiosity, it is actually a good idea that i bring them to check they are OK?
The proper procedure is get a tech to install / bias the tubes. The tech will then run the amp up to full power and check it on a cro to make sure everything is OK.
There are also other things I usually do to see if the tubes show indication of early failure.
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CRO for all those that do not know is a Cathode-Ray Oscilloscope.
Distributors are just that, box shifters. Manufactures may test one in 100 tubes from a batch on new tubes (China) or more expensive types per individual tube.
I think Terry is correct in saying you should have a tech check the bias and output for oscillation particularly if you have just parted with some serious bucks for valves. Think of it as a service the same as the car needs but not as frequent. If your tubes are oscillating they may burn out your tweeters pretty quickly so it's down to common sense.
Mario I have a present for you, A CRO which should give you the ability to check out any valve installs along with your tube tester - will bring it next visit. ;D ;D
Any sign of crystals in the stars................................................ ???
V :D
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CRO for all those that do not know is a Cathode-Ray Oscilloscope.
Distributors are just that, box shifters. Manufactures may test one in 100 tubes from a batch on new tubes (China) or more expensive types per individual tube.
Honestly, I'd be surprised if -any- manufacturer tested 1 in 100. That would appear to be dumb business practice WRT the variable nature of tube manufacturing.
I think Terry is correct in saying you should have a tech check the bias and output for oscillation particularly if you have just parted with some serious bucks for valves. Think of it as a service the same as the car needs but not as frequent. If your tubes are oscillating they may burn out your tweeters pretty quickly so it's down to common sense.
Mario I have a present for you, A CRO which should give you the ability to check out any valve installs along with your tube tester - will bring it next visit. ;D ;D
Any sign of crystals in the stars................................................ ???
V :D
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CRO for all those that do not know is a Cathode-Ray Oscilloscope.
Distributors are just that, box shifters. Manufactures may test one in 100 tubes from a batch on new tubes (China) or more expensive types per individual tube.
I think Terry is correct in saying you should have a tech check the bias and output for oscillation particularly if you have just parted with some serious bucks for valves. Think of it as a service the same as the car needs but not as frequent. If your tubes are oscillating they may burn out your tweeters pretty quickly so it's down to common sense.
Mario I have a present for you, A CRO which should give you the ability to check out any valve installs along with your tube tester - will bring it next visit. ;D ;D
Any sign of crystals in the stars................................................ ???
V :D
Steve , I have a cro , fancy showing me how to use it some time ?
G
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:D :D Zen....I can see that crystal winking at me :-* :-* :-* :-*................There's nowt fair in love and business, it's whatever they can get away with without being caught. :'(
Oz, check out utube, it has some really good demo's of CRO's testing various bits and bobs, you can view these at your leisure which I think takes the 'pressure off' a bit when trying to get your head around something new. ::)
V ;D
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CRO for all those that do not know is a Cathode-Ray Oscilloscope.
Distributors are just that, box shifters. Manufactures may test one in 100 tubes from a batch on new tubes (China) or more expensive types per individual tube.
I think Terry is correct in saying you should have a tech check the bias and output for oscillation particularly if you have just parted with some serious bucks for valves. Think of it as a service the same as the car needs but not as frequent. If your tubes are oscillating they may burn out your tweeters pretty quickly so it's down to common sense.
Mario I have a present for you, A CRO which should give you the ability to check out any valve installs along with your tube tester - will bring it next visit. ;D ;D
Any sign of crystals in the stars................................................ ???
V :D
A cro i hope it comes with dodo instructions or zenelectro will be teaching me
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:D :D Zen....I can see that crystal winking at me :-* :-* :-* :-*................There's nowt fair in love and business, it's whatever they can get away with without being caught. :'(
Oz, check out utube, it has some really good demo's of CRO's testing various bits and bobs, you can view these at your leisure which I think takes the 'pressure off' a bit when trying to get your head around something new. ::)
V ;D
vitavox the new clock has to go past kajak12 strict testing before delivery to new owner :P
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Mario, what exactly were they doing, you say 'unstable'? They might even be oscillating which can look like a fluctuating DC current with an ohm meter. You need to get a cro if you
The needle wont stay still only happened on 3 el34's so far it jumps like a yoyo all done using my avo tester 160
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OK guys, so today I had my first chance to sit down with the MingDa MC34-AB that I bought from mcb.
It's a nice amp and a big contrast to my Naksa 70. Those of you who have read this thread will know that this particular amp has been partly upgraded by mcb (mainly by replacing cheap capacitors with better ones), but not so far as flemo's (not mcb's) has been... so there is room for improvement. Also, I must say that the Winged C El34's are brand new and had only been run for a few hours. Mario reckons they need at least 100 hours to settle in sonically.
I found that while some tracks sounded very good, others could sound a bit thick and muddled. I first noticed this playing Ella & Louis, but it sounded its worst playing Steve Hoffman's Gold disc of the Doors' L.A. Woman. I actually thought it worse than the Naksa and decided at that point to change to the Naksa to confirm this. As it happens, I had a friend with me who bought his Graaf 200 W/channel OTL valve amp. Changing back to the Naksa was interesting: while the clarity of the separate instruments returned (the MingDa sounded rather muddled), the Naksa did sound a bit anaemic in comparison. Indeed, my valve-amp friend took an immediate dislike to it and preferred the MingDa, even though he conceded the Naksa was clearer in the high frequencies.
At this point we fired up the Graaf for the first time. This is a very nice amp: it combined the weighty organic sound of the MingDa (a valve sound, i suppose) with the clarity of the Naksa. Indeed, everything sounded better through the Graaf. It's a beast of an amp though and pumps out heat like crazy:
(http://usr.audioasylum.com/images/5/52671/graaf_21.jpg).
It was pleasing to hear how much better my system can sound with a better amp, still using my PDX Level 2 DAC. The experience makes we want to tweak the MingDa. I want to remove the somewhat muddled lumpiness and get some detail, clarity and air. This may involve replacing some of the small valves and the AmpOhm caps.
Unfortunately the timing isn't great for personal reasons, and I won't touch it for a few weeks, but I am (somewhat nervously) excited about starting on this journey...
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A few weeks will give you some time to run the tubes in.
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That Graaf does look HOT! (no pun intended...really!)
As said those EL34s need more hours on them by the sounds of it.
Oh! and when you do some upgrades on the Ming-Da try some of the Neotech copper wire in place of what is in it now, if what's in it is original stuff. should help with that clarity you are looking for :)
Should be fun working on that Ming-Da 8)
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That Graaf does look HOT! (no pun intended...really!)
As said those EL34s need more hours on them by the sounds of it.
Oh! and when you do some upgrades on the Ming-Da try some of the Neotech copper wire in place of what is in it now, if what's in it is original stuff. should help with that clarity you are looking for :)
Should be fun working on that Ming-Da 8)
Yes rab neotech wire is a must for mingda also other modds and it will all come together like a happy family
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Hi rab,
That Graaf is a monster.
It will be interesting to read how the MD changes with a few hours on the Winged C's.
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zenelectro writes
The proper procedure is get a tech to install / bias the tubes. The tech will then run the amp up to full power and check it on a cro to make sure everything is OK.
+1 to this very sound advice you cant always identify whats going on without the right equipment and detailed knowledge, making sure everything is okay is a good investment....
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Yes rab neotech wire is a must for mingda also other modds and it will all come together like a happy family
Thanks Mario. I saw the eBay info for this wire on the other thread and will buy some from there.
But here's a question: how much should I buy? I suppose ideally all of the wire throughout the amp would be replaced, but is it necessary to do that, or mainly just, say, in the signal paths or the like? Would, say, 2m be enough?
Here's another (dumb) question: given that the amp idles with about 32mA of plate current running through the EL34s, can the 'run in' be accomplished with the amp just idling, or does it need an audio signal?
- r.
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There may possibly be of some benefit elsewhere, just need to get the size right for the purpose I guess...maybe the 20awg would be OK for power and such, but I haven't tried it, for signal the 24awg should be fine, or go the 20awg if you like.
The Teflon dielectric is rated to 600vdc I think?
I don't know how much though you will need, I'll leave that for Mario.
There seems to be very little run-in with this wire, the character doesn't really change, it just opens up some over the first few days or week of use. I wouldn't leave the amp idling with no signal... that just cooks the valves or that is how I understand it, best to just use it as you normally would.
No questions are dumb 8)
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Yes rab neotech wire is a must for mingda also other modds and it will all come together like a happy family
Thanks Mario. I saw the eBay info for this wire on the other thread and will buy some from there.
But here's a question: how much should I buy? I suppose ideally all of the wire throughout the amp would be replaced, but is it necessary to do that, or mainly just, say, in the signal paths or the like? Would, say, 2m be enough?
Here's another (dumb) question: given that the amp idles with about 32mA of plate current running through the EL34s, can the 'run in' be accomplished with the amp just idling, or does it need an audio signal?
- r.
Get the 20awg for the mingda you will use this wire for the input signal to the grid of the tubes order about 10m as you will use it during your diy journey,Run music on low volume or get 40w 8ohm resistors and put them on the speaker binding posts.
i will ring you on the weekend and explain what you will be doing to the amp.
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Get the 20awg for the mingda you will use this wire for the input signal to the grid of the tubes order about 10m as you will use it during your diy journey,Run music on low volume or get 40w 8ohm resistors and put them on the speaker binding posts.
i will ring you on the weekend and explain what you will be doing to the amp.
Thanks Mario; I will order the 20AWG wire...
Incidentally, I was also about to order a Jensen electrolytic cap to replace the one remaining blue cap (as you pointed out in the other MingDa thread), but I notice that cap is under a bridge rectifier and is right near the small PCB that controls the volume control motor and associated logic. I speculate that the cap is just a power supply smoothing cap for a supply that only runs that logic board, and therefore there may be no point in replacing it if it is only to run that small digital circuit...?
Incidentally, I would be grateful if you sent me a schematic of the amp.
- r.
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Incidentally, I was also about to order a Jensen electrolytic cap to replace the one remaining blue cap (as you pointed out in the other MingDa thread), but I notice that cap is under a bridge rectifier and is right near the small PCB that controls the volume control motor and associated logic. I speculate that the cap is just a power supply smoothing cap for a supply that only runs that logic board, and therefore there may be no point in replacing it if it is only to run that small digital circuit...?
Incidentally, I would be grateful if you sent me a schematic of the amp.
- r.
Anyone know what the bridge rectifier is for?
Z
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Oh, one more question: although the coupling caps for the front 4 valves have been replaced, i have not seen any mention or suggestion on this forum of replacing the 8 MingDa-branded coupling caps for the EL34s. Why is that? Presumably those caps are rubbish and I would have expected that those would be replaced before the resistors...?
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Anyone know what the bridge rectifier is for?
Am i missing something? Presumably the amp has different AC lines coming from (presumably different windings) of the external transformers... the bridge is just to rectify the AC to DC for the digital board... or so i speculate!
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Incidentally, I was also about to order a Jensen electrolytic cap to replace the one remaining blue cap (as you pointed out in the other MingDa thread), but I notice that cap is under a bridge rectifier and is right near the small PCB that controls the volume control motor and associated logic. I speculate that the cap is just a power supply smoothing cap for a supply that only runs that logic board, and therefore there may be no point in replacing it if it is only to run that small digital circuit...?
Incidentally, I would be grateful if you sent me a schematic of the amp.
- r.
Hi Rab,
I don't think that cap is for the vol motor control. Flemo replaced this cap in my (the ex flemo) amp a while ago and as you know, it does not have the remote volume control.
With regard to you question about the coupling caps for the EL34's. I am pretty sure that they where on Mario's hit list. I took one look at where they where located and decided that replacing them looked too hard for me.
I get the impression your brain is working overtime at the moment, scheming up possible mods ;D.
Murray
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Oh, one more question: although the coupling caps for the front 4 valves have been replaced, i have not seen any mention or suggestion on this forum of replacing the 8 MingDa-branded coupling caps for the EL34s. Why is that? Presumably those caps are rubbish and I would have expected that those would be replaced before the resistors...?
What value are they? 1uf aren't they?
I guess if replacing with something of high quality like Duelunds there is cost and also space could be an issue, for a Duelund Alexandra of 1uf ya' looking at around $100 each and they are 45mm x 62mm. There are 8 of them and space seems non existent for caps of the Duelund's size, would need to suspend them above (that being below when the amp is right way up)
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Oh, one more question: although the coupling caps for the front 4 valves have been replaced, i have not seen any mention or suggestion on this forum of replacing the 8 MingDa-branded coupling caps for the EL34s. Why is that? Presumably those caps are rubbish and I would have expected that those would be replaced before the resistors...?
Hi rab regarding el34 decoupling caps flemo didn't whant to spend the cash to replace them with something and yes the caps used will be sh!t.
flemo's amp was modded on the cheap heaps more can be done if funds are available.
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Incidentally, I was also about to order a Jensen electrolytic cap to replace the one remaining blue cap (as you pointed out in the other MingDa thread), but I notice that cap is under a bridge rectifier and is right near the small PCB that controls the volume control motor and associated logic. I speculate that the cap is just a power supply smoothing cap for a supply that only runs that logic board, and therefore there may be no point in replacing it if it is only to run that small digital circuit...?
Incidentally, I would be grateful if you sent me a schematic of the amp.
- r.
Anyone know what the bridge rectifier is for?
Z
negative bias for el34's
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i did the 8 x 1uf caps with jensen copper. stock was better. its a sh!te job to do as well.
In retrospect i wouldn't bother
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i did the 8 x 1uf caps with jensen copper. stock was better. its a sh!te job to do as well.
In retrospect i wouldn't bother
Hi crazikid: and interesting - and unexpected - result! And then (judging by flemo's pics) you changed the caps back again?
Incidentally, I trawled the web and came across an Audiogon advert for a modded one of these amps with all of those caps replaced with "Russian K-40s and K-75s", see here: http://new.audiogon.com/listings/30344 (http://new.audiogon.com/listings/30344).
Pic:
(http://media-audiogon-com.s3.amazonaws.com/uploads/image/image/194557/scaled_1306110181.jpg)
According to the seller, "The change made a dramatic difference in sound and detail and continues to improve as they are still breaking in." But then he changed the coupling caps for the small valves at the same time, so I suppose the change could have been dominated by those...
I now have a schematic of the amp: to my untrained eye, the circuit looks about as simply as you could imagine for a high power push-pull topology. I was interested to see that the only differences between the 'power amp' and 'integrated' modes seem to be that the input selector and volume controls (but interestingly nothing else) are bypassed and that a different (parallel RC) filter is used for the global feedback loop. Any ideas why the latter would be the case? I
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I don't think that cap is for the vol motor control. Flemo replaced this cap in my (the ex flemo) amp a while ago and as you know, it does not have the remote volume control.
Interesting. I will try to trace the rectifier output the next time i have the amp open. I note that the volume control logic circuit is not included in the MingDa schematic. The rectifier for the bias voltages is shown as being part of the power supply in a separate schematic, which I assume (possibly incorrectly) means that circuit is in the separate supply box thingy. I note there are two 3.15VAC taps coming off the same circuit... perhaps those are for the digital circuitry? If so, there would need to be a third bridge rectifier.
I get the impression your brain is working overtime at the moment, scheming up possible mods ;D.
Well, not really... i lack the knowledge to come up with my own mods! I will be relying on Mario's expertise... I am just trying to understand the amplifier circuit on paper and in hardware!
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I don't know if It's just the photo, but those four caps in the center look to be positioned badly, unless they are raised higher than what it looks.
I would be inclined to stand the caps well away from the valve pins, say about 1 inch away, maybe a bit more. Edit: defiantly more now that I think about the HV of the anode and screen.
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I don't know if It's just the photo, but those four caps in the center look to be positioned badly, unless they are raised higher than what it looks.
Agreed. I don't think it's the photo: those central caps will be cooked!
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Possibly cause more serious problems too.
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i did the 8 x 1uf caps with jensen copper. stock was better. its a sh!te job to do as well.
In retrospect i wouldn't bother
i would have to agree with this one.
its fun to play with different caps, but personally, I wouldn't recommend spending too silly $ on them. For example 8x1uf Jensen coppers ($60x8=$480+postage).
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i did the 8 x 1uf caps with jensen copper. stock was better. its a sh!te job to do as well.
In retrospect i wouldn't bother
i would have to agree with this one.
its fun to play with different caps, but personally, I wouldn't recommend spending too silly $ on them. For example 8x1uf Jensen coppers ($60x8=$480+postage).
the jensen pio are very thin sounding cap
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i will ring you on the weekend and explain what you will be doing to the amp.
OK Mario, I am now ready for your call when you are!
I have run the amp for over 100 hours now. I haven't yet sat down and listened carefully, but my impression is that the sound has not improved substantially, if at all.
It strikes me that these amps are pretty simple in topology, as presumably is your own amp (simplest is best?), which I think also runs 8 Winged C EL34s. Would it therefore be possible to effectively convert my MingDa into something close to your amp by first making it have the same topology (presumably not that different in any case?) and substituting parts over time? ... or am I dreaming?
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i will ring you on the weekend and explain what you will be doing to the amp.
OK Mario, I am now ready for your call when you are!
I have run the amp for over 100 hours now. I haven't yet sat down and listened carefully, but my impression is that the sound has not improved substantially, if at all.
It strikes me that these amps are pretty simple in topology, as presumably is your own amp (simplest is best?), which I think also runs 8 Winged C EL34s. Would it therefore be possible to effectively convert my MingDa into something close to your amp by first making it have the same topology (presumably not that different in any case?) and substituting parts over time? ... or am I dreaming?
rab post some internal photos of your amp or email them to me high rez
my amp uses valve rectification i am sure paul could do yours but he needs your amp