Author Topic: My new amp  (Read 22843 times)

Offline springcreek

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Re: My new amp
« Reply #40 on: January 02, 2014, 08:09:27 PM »
Cool let me know how it goes William.

Cheers, Andy

Offline Jehuty

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Re: My new amp
« Reply #41 on: January 03, 2014, 10:22:00 PM »
Hi Andy,

If you're looking for an oil filled choke, this could work very well: http://www.ebay.com.au/itm/220793933835

That is the choke that Steve uses in his PX4 amp. I have already got a pair in my type 50 amp. I just measured the resistance and it's 93 ohms, pretty close to 100 ohms  8)

For the money it's a bargain, you only need to convince the seller to ship to Australia which I think it won't be hard since it's been on eBay for ages. Grab a pair while you're at it too!  ;D

Cheers,
William
Not all that matters can be measured, not all that can be measured matters.

Offline zenelectro

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Re: My new amp
« Reply #42 on: January 04, 2014, 12:44:20 AM »
Hi Andy,

If you're looking for an oil filled choke, this could work very well: http://www.ebay.com.au/itm/220793933835

That is the choke that Steve uses in his PX4 amp. I have already got a pair in my type 50 amp. I just measured the resistance and it's 93 ohms, pretty close to 100 ohms  8)

For the money it's a bargain, you only need to convince the seller to ship to Australia which I think it won't be hard since it's been on eBay for ages. Grab a pair while you're at it too!  ;D

Cheers,
William

Ask the seller - How many Henrys?

That's the important spec.

Z



Offline Jehuty

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Re: My new amp
« Reply #43 on: January 04, 2014, 01:01:49 AM »
Hi Terry,

It's 8 henry, 200mA. I knew since I got a pair at home  8)

Cheers,
William
Not all that matters can be measured, not all that can be measured matters.

Offline Jehuty

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Re: My new amp
« Reply #44 on: January 04, 2014, 01:07:53 AM »
Hi Terry,

While you're at it, what sort of choke specs would you recommend to replace the R21 in the attached schematic? The R21 is on the top right corner next to the C13 and GZ34.

Cheers,
William
« Last Edit: January 04, 2014, 01:16:39 AM by Jehuty »
Not all that matters can be measured, not all that can be measured matters.

Offline zenelectro

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Re: My new amp
« Reply #45 on: January 04, 2014, 10:30:51 AM »
Hi Terry,

While you're at it, what sort of choke specs would you recommend to replace the R21 in the attached schematic? The R21 is on the top right corner next to the C13 and GZ34.

Cheers,
William

Hi William,

Replacing R21 with a choke may or may not be an improvement.
You will certainly get lower PS ripple / noise for sure and even 1 Henry will be improvement over straight resistor.

The caveat is that (and not many people understand this) the 2 caps and inductor (choke) resonate, ie;
bounce like an un damped spring depending on the values.

I did a simulation of this circuit and at 1H it is pretty well behaved but at say 5H there is a lot of 'bounce'.
This will have some sonic effect.

Zen idea - You can actually put various damping networks in and get the benefits of a large choke (say 5H / 10H) with
no 'bounce' but I have never seen this done on any classic valve amp.

Maybe time to try this out Steven / Vita - it should have way more impact than any piece of wire etc. :) 

So to answer your question, William - around 1H / probably 4H max at a guess should be good but keep DC R to 100R or less.

Z



Offline Jehuty

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Re: My new amp
« Reply #46 on: January 04, 2014, 12:27:40 PM »
Hi Terry,

While you're at it, what sort of choke specs would you recommend to replace the R21 in the attached schematic? The R21 is on the top right corner next to the C13 and GZ34.

Cheers,
William

Hi William,

Replacing R21 with a choke may or may not be an improvement.
You will certainly get lower PS ripple / noise for sure and even 1 Henry will be improvement over straight resistor.

The caveat is that (and not many people understand this) the 2 caps and inductor (choke) resonate, ie;
bounce like an un damped spring depending on the values.

I did a simulation of this circuit and at 1H it is pretty well behaved but at say 5H there is a lot of 'bounce'.
This will have some sonic effect.

Zen idea - You can actually put various damping networks in and get the benefits of a large choke (say 5H / 10H) with
no 'bounce' but I have never seen this done on any classic valve amp.

Maybe time to try this out Steven / Vita - it should have way more impact than any piece of wire etc. :) 

So to answer your question, William - around 1H / probably 4H max at a guess should be good but keep DC R to 100R or less.

Z

Hi Terry,

Thanks for the explanation, always appreciate your input :)

Yes, I read about that resonating power supply on DIY Audio forum (see http://www.diyaudio.com/forums/pass-labs/50061-crcrc-vs-lclclc-better-why.html#post558136) and I was wondering what it meant.

In that thread Nelson Pass suggest we use "porno" big cap after the L and add small value resistors across the inductors to help damping out the system. He did mention the resistors value about 10 ohm or less but he never said anything about the value of the big cap (I guess it all depends on the circuit). Now back to the Leak Stereo 20 circuit I posted above, would 252uF be enough for this? Taking into account using the 8 henry choke on eBay or even bigger like 10 henry.

I asked because I read on the Leak Yahoo Group that paralleling 100uF or bigger to C12 (32uF) would yield improvement in the bass respond and I have already bought a cheapo Panasonic electrolytic 220uF/400VDC just to try this out. It would be good if the increase capacitance in C12 does help damping out the system too. Or should we use even bigger cap say 1000uF? "Porno" big confuses me  ??? ??? ;D

Thanks,
William
Not all that matters can be measured, not all that can be measured matters.

Offline zenelectro

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Re: My new amp
« Reply #47 on: January 04, 2014, 01:22:35 PM »
Hi Terry,

While you're at it, what sort of choke specs would you recommend to replace the R21 in the attached schematic? The R21 is on the top right corner next to the C13 and GZ34.

Cheers,
William

Hi William,

Replacing R21 with a choke may or may not be an improvement.
You will certainly get lower PS ripple / noise for sure and even 1 Henry will be improvement over straight resistor.

The caveat is that (and not many people understand this) the 2 caps and inductor (choke) resonate, ie;
bounce like an un damped spring depending on the values.

I did a simulation of this circuit and at 1H it is pretty well behaved but at say 5H there is a lot of 'bounce'.
This will have some sonic effect.

Zen idea - You can actually put various damping networks in and get the benefits of a large choke (say 5H / 10H) with
no 'bounce' but I have never seen this done on any classic valve amp.

Maybe time to try this out Steven / Vita - it should have way more impact than any piece of wire etc. :) 

So to answer your question, William - around 1H / probably 4H max at a guess should be good but keep DC R to 100R or less.

Z

Hi Terry,

Thanks for the explanation, always appreciate your input :)

Yes, I read about that resonating power supply on DIY Audio forum (see http://www.diyaudio.com/forums/pass-labs/50061-crcrc-vs-lclclc-better-why.html#post558136) and I was wondering what it meant.

In that thread Nelson Pass suggest we use "porno" big cap after the L and add small value resistors across the inductors to help damping out the system. He did mention the resistors value about 10 ohm or less but he never said anything about the value of the big cap (I guess it all depends on the circuit). Now back to the Leak Stereo 20 circuit I posted above, would 252uF be enough for this? Taking into account using the 8 henry choke on eBay or even bigger like 10 henry.

I asked because I read on the Leak Yahoo Group that paralleling 100uF or bigger to C12 (32uF) would yield improvement in the bass respond and I have already bought a cheapo Panasonic electrolytic 220uF/400VDC just to try this out. It would be good if the increase capacitance in C12 does help damping out the system too. Or should we use even bigger cap say 1000uF? "Porno" big confuses me  ??? ??? ;D

Thanks,
William

The values change for every application.

You have to run it through a simulator and observe the ringing. So what works for Pass amp will be way off
for a tube amp. All the components will 'react' with each other.

For all these upgrades / mods best option is formulate a plan - don't just buy parts at random. You will end
up spending a lot of money.

Z




Offline vitavoxdude

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Re: My new amp
« Reply #48 on: January 04, 2014, 01:41:34 PM »
GZ34 should not look into a large cap prior to the inductor, it's currently set at 16 uF, the maximum safe load.  After the resistor (or choke as you want to insert)its a different matter. I would keep the power supply design as is, change out the resistor for a tantalum if you can get the power handling and replace the caps with some Jensen 4 poles.

Porno big, well yes that's an expression to mean huge(as in the male appendages that they hire the blokes for in colourful movies- pornography)! :o  Bigger caps do not always = better sound, as Zen has  mentioned the leak is a tuned circuit which you will potentially upset with a large inductor. 

Large caps can slow down the sound and your amp is never going to be a bass monster so forget about placing massive caps after the resistor.  Even changing to PP caps may unbalance the sound, you can always try them but you may not prefer them.  Now the most important piece of advice I can give, only do one change at a time and see if its better or worse; changing too many things at once its impossible to say which way things are going.  Leak had a whole design team of engineers, I think they would have spent many months finalising the sound to what it currently has, changing the circuit in the way you describe may alter it to being a far worse performer than it is unmodified.

So come on Zen, share this latest supply wonder, is it the 'electronic choke by chance?  ::)

I never denigrate the hard work done by others (and I am thinking of Steve V here) when it comes to the hard yards of trying out many different combinations of components and circuits for the benefit of others; I particularly enjoyed reading the recent experience with the AN resistors, the same material but different outcomes.................. :-X

I suppose I also accept that its all about the circuit and the way various items react with each other and simulations done with the Duncan pwr supply designer etc will not reveal what they sound like, only measure / resonate / bounce. :'(  For the many who took the leap of faith into the NOS world of the KDAC did we all fry our tweeters with the RF noise, well hell no.  I know faith can be blind but perfectly measuring equipment sounds bland and sterile, I have many such pieces gathering dust.  :(

The Leak stereo 20 is not a bad amp, it's not the best Leak by a country mile, messing with the circuit is going to upset it, by all means use the best valves and components but alter the overall circuit at your peril. ::)  IMV the correct biasing of the valves will bring more reward than swapping many components, get that right before attempting any more 'tweaks'.  :o
V :)
V
We all like different things so lets all agree to disagree and if any common ground is found then worship it.  Mine is the KD hence being present on this forum.

Offline Jehuty

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Re: My new amp
« Reply #49 on: January 04, 2014, 01:56:40 PM »
Thanks for the advice gents. They all make sense and are appreciated  :)

That's actually my plan, not to mess around with the original circuit as I'd like to keep the Leak small and simple. Adding a big choke will probably need external power supply and that defeat the purpose of small and simple. The only thing that I will try is paralleling the C12, it's cheap only $3, doesn't need an external power supply and who knows, I might like it  ;)

Cheers,
William
Not all that matters can be measured, not all that can be measured matters.

Offline zenelectro

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Re: My new amp
« Reply #50 on: January 04, 2014, 06:51:37 PM »

Leak had a whole design team of engineers, I think they would have spent many months finalising the sound to what it currently has, changing the circuit in the way you describe may alter it to being a far worse performer than it is unmodified.


I think you might be putting just a touch too much subjective wind in these designers sails. These guys didn't really know what they were creating, subjectively speaking in the grand scheme of things.
They were just doing the best they could with what was available. Carbon comp resistors were it, polyester caps were it. 
They were actually mainly going for low measured distortion and linearity hence the Ultra Linear OP stage and plenty of global FB. The same goes for the designers of the very first solid state mixing consoles they
honestly thought they would sound much better than their valve predecessors!

History tells us it didn't quite pan out that way. A friend of mine, years ago interviewed the great Rupert Neve and pretty much same story - he wished for quite a while that all those
early SE / choke loaded SS mix consoles would go away so people would embrace his newer and what he genuinely believed were superior sounding and measuring consoles. A lot of the stuff he does now
goes back to and draws heavily from the early vintage era SE designs - because that is peoples preference.
 
Quote

So come on Zen, share this latest supply wonder, is it the 'electronic choke by chance?  ::)


No I have never been interested in EC's. I have just observed that most of these typical CLC power supplies ring (oscillate) when I put them in a simulator - some quite badly.
My real life experience on various circuit elements supports this. It's a matter of being aware of it and having the counter measure in your 'tool box' to try.

Years ago I did a mix console upgrade in a studio, replaced all opamps, biased them into class A etc. Had to use more local decoupling caps Result was + step in all areas but it sounded a bit edgy and etched.
The engineer said I had increased the HF response. I said no it's something else, the response is flat - thinking on my feet I proceeded to insert a 5 or 10 ohm R feeding every bypass cap to separate them with a lossy type network and bingo - edge gone. They were ringing at some VHF.
 
Quote

I never denigrate the hard work done by others (and I am thinking of Steve V here) when it comes to the hard yards of trying out many different combinations of components and circuits for the benefit of others; I particularly enjoyed reading the recent experience with the AN resistors, the same material but different outcomes.................. :-X


Maybe it's unintentional, however I see quite a degree of denigration - towards more modern designers / designs. A lot of these people have put a huge amount of work into the advancement of audio.
Their intentions are absolutely honorable however full understanding of objective versus subjective can take a lifetime to get a handle on - see R Neve above. Same goes for TDA1540/1, a brilliant Dutch engineers
work. He was doing same thing - just the best he could with the technology at that time. It was a big part fluke that it ended up being subjectively possibly the best sounding DAC ever made.

Quote

I suppose I also accept that its all about the circuit and the way various items react with each other and simulations done with the Duncan pwr supply designer etc will not reveal what they sound like, only measure / resonate / bounce. :'( 


Duncan's is great for quick and dirty - but it does make some interesting mistakes. Spice is the ticket and much better, but as always its GIGO. I use them as helpers to see a potential issue, to tell me where to
look, where to tweak. That's what they are good for.   

Quote

For the many who took the leap of faith into the NOS world of the KDAC did we all fry our tweeters with the RF noise, well hell no.  I know faith can be blind but perfectly measuring equipment sounds bland and sterile, I have many such pieces gathering dust.  :(


I don't think 0 x OS has ever been a major LOF it's not unfiltered DSD :) I'd been meaning to try it for years ever since Kusunoki / Thorsten did it.

In the end this all should be part of a timeline of knowledge gathering - not an absolute serving peoples egos. Too common in this game.

Quote

The Leak stereo 20 is not a bad amp, it's not the best Leak by a country mile, messing with the circuit is going to upset it, by all means use the best valves and components but alter the overall circuit at your peril. ::)  IMV the correct biasing of the valves will bring more reward than swapping many components, get that right before attempting any more 'tweaks'.  :o
V :)
V

I think a small / moderate sized inductor in the power supply to replace the R is a pretty safe bet on an improvement with the Leak. I like the design in general, quite
simple and efficient.


Z

 


Offline Erik van Voorst

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Re: My new amp
« Reply #51 on: January 06, 2014, 03:04:24 AM »
Let the mods begin!  ;D

 Only JJ electrolytics as my budget is limited, maybe next year for Jensen if I can be bothered. I got all tantalum resistors however, Shinkoh wherever possible, Audio Note to cover the rest. Cost me about $350, yep, just resistors>:(


Do not under estimate the JJ,  in my pre amp it outperformed the Jensen in a listening session..so be cautious not to buy things based on the name...to me there is no such thing as one size fits all... ;)
No need to tell you that resistorwise you chose well...although you can still "season"  your amp with them  8)

Offline Jehuty

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Re: My new amp
« Reply #52 on: January 06, 2014, 03:20:01 AM »
Let the mods begin!  ;D

 Only JJ electrolytics as my budget is limited, maybe next year for Jensen if I can be bothered. I got all tantalum resistors however, Shinkoh wherever possible, Audio Note to cover the rest. Cost me about $350, yep, just resistors>:(


Do not under estimate the JJ,  in my pre amp it outperformed the Jensen in a listening session..so be cautious not to buy things based on the name...to me there is no such thing as one size fits all... ;)
No need to tell you that resistorwise you chose well...although you can still "season"  your amp with them  8)

Hi Erik,

Thanks for the advice. Yes, I am very well aware that JJ is very good and affordable too, hence I said above "if I can be bothered to change to Jensen"  ;)

I bought some more Allen Bradley 2 watt resistors to "season" more. I would also like to try Riken or Amtrans in the future, all good fun!

Regards,
William
Not all that matters can be measured, not all that can be measured matters.

Offline zenelectro

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Re: My new amp
« Reply #53 on: January 06, 2014, 09:10:53 AM »
Let the mods begin!  ;D

 Only JJ electrolytics as my budget is limited, maybe next year for Jensen if I can be bothered. I got all tantalum resistors however, Shinkoh wherever possible, Audio Note to cover the rest. Cost me about $350, yep, just resistors>:(


Do not under estimate the JJ,  in my pre amp it outperformed the Jensen in a listening session..so be cautious not to buy things based on the name...to me there is no such thing as one size fits all... ;)
No need to tell you that resistorwise you chose well...although you can still "season"  your amp with them  8)

Hi Erik,

Thanks for the advice. Yes, I am very well aware that JJ is very good and affordable too, hence I said above "if I can be bothered to change to Jensen"  ;)

I bought some more Allen Bradley 2 watt resistors to "season" more. I would also like to try Riken or Amtrans in the future, all good fun!

Regards,
William

WRT Jensen also bear in mind 4 pole Jensen versus normal HV types.

The 4 poles IME sound cleaner / clearer and the high voltage types richer. The 4 poles also benefit from utilising the ground connection 'break' which
is not always possible, depends on circuit. 

Z


Offline Jehuty

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Re: My new amp
« Reply #54 on: January 07, 2014, 03:06:17 AM »
Z, can we use 4 pole Jensen in the Leak 20? Say for example replacing the C12...
Not all that matters can be measured, not all that can be measured matters.

Offline zenelectro

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Re: My new amp
« Reply #55 on: January 07, 2014, 10:50:53 AM »
Z, can we use 4 pole Jensen in the Leak 20? Say for example replacing the C12...


Yep, both caps can be replaced with 4 poles and have the benefit of proper 4 pole connection.
The grounding might have to be rewired a little but should be no problems.

In fact by adopting this type of connection you are optimising PS grounding the way it should be done. I see some pretty creative
grounding schemes in my travels :)


Offline springcreek

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Re: My new amp
« Reply #56 on: January 14, 2014, 08:16:00 AM »
Hi all

Looks like there has been a great discussion while I've been up in the mountains. Thanks for advancing this guys, some great information.

Does not sound like the CLC is the way to go for the Leak. I don't want to lose the speed of the amp, I was just chasing more wetness and richness.

Zen is there much benefit in going from the Solen I have used in the power supply to Jensen 4 poles? I am still getting some residual hum from the power supply, but that may be reduced by a slightly larger cap?

A am keen to replace most of the remaining cheap carbon resistors with 2 watt Allen Bradley's and a sprinkling of Shinkoh's, especially on the input. I am also keen to get rid of the small electrolytics and was planning to use Solen's here as Steven did. Any thoughts?

I would like to take the Leak as far as possible. I'm not really trying to turn it into a bass monster, but maximise the things it already does well.

Cheers

Offline ozmillsy

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Re: My new amp
« Reply #57 on: January 14, 2014, 10:20:39 PM »
If there is a sliding scale from 0 to 10 where....

0 = Full, rich, thick, heavy
10 = Clean, detailed, fast, thin

Then a stock Leak leans towards a 7 to 8, in my opinion.  The best sounding Leak I've heard was SV's Leak,  and he had to work hard to get the body into it that it lacked (cant believe he sold it).  

Building on the strengths that are already there isnt necessarily where the magic is.  Gotta give it what it needs.

The Allen Bradleys should go well. As I understand, they need a bit of time in circuit.

Have fun with it.

It's all about the music,, not the equipment.

Offline springcreek

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Re: My new amp
« Reply #58 on: January 14, 2014, 10:35:57 PM »
Well that's what I'm hearing. Keen to add the AB's and see how far that takes me. It is why I was keen on the oil filled choke and vintage PIO caps.

Will try and find some richer, warmer sounding input tubes/phase splitters.

Cheers

Offline zenelectro

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Re: My new amp
« Reply #59 on: January 15, 2014, 11:35:37 AM »
Hi all

Looks like there has been a great discussion while I've been up in the mountains. Thanks for advancing this guys, some great information.

Does not sound like the CLC is the way to go for the Leak. I don't want to lose the speed of the amp, I was just chasing more wetness and richness.

Zen is there much benefit in going from the Solen I have used in the power supply to Jensen 4 poles? I am still getting some residual hum from the power supply, but that may be reduced by a slightly larger cap?

A am keen to replace most of the remaining cheap carbon resistors with 2 watt Allen Bradley's and a sprinkling of Shinkoh's, especially on the input. I am also keen to get rid of the small electrolytics and was planning to use Solen's here as Steven did. Any thoughts?

I would like to take the Leak as far as possible. I'm not really trying to turn it into a bass monster, but maximise the things it already does well.

Cheers

WRT Leak sounding clean versus rich - this doesn't surprise me a bit. The design uses lots of feedback both local, in the OP stage itself and global which comes back to V1 under the cathode.

As such it's difficult to 'tune' this amp to sound more like a non feedback SET - whatever you do to add richness - the feedback loop will be fighting against that to bring it back.

WRT PS hum - just make sure it is the power supply and not AC heater bleeding through somewhere.

If you guys are wanting a sound closer to SV's 45 SET amps but with more power, a non feedback, push pull amp, Triode connected is a better way to go. 4 x EL84's will get you about 15 watts.

Check schem below for what I mean - just use 4 OP tubes and 1 IP tube. This will sound really good even with average parts - but you'll need decent transformers.

cheers

Z
« Last Edit: January 15, 2014, 11:38:30 AM by zenelectro »