Author Topic: Tubelover 112a/26 DHT preamp  (Read 8566 times)

Offline Tuyen

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Tubelover 112a/26 DHT preamp
« on: March 26, 2014, 07:52:29 PM »
A preamp built by Tubelover in Indonesia.  Any recommendations on which tubes I should look for and/or other internal components that I should pay attention to?

Details:  Tubelover 26/112A DHT preamp.    Philips AX50 full wave rectifier, Cunningham CX-326 DHT tubes, Parmeko iron, blackgates, Rod Coleman voltage regulators, noble stepped attenuator, riken carbon film resistors & duelund vsf output capacitors.




Offline stevenvalve

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Re: Tubelover 112a/26 DHT preamp
« Reply #1 on: March 27, 2014, 01:22:38 AM »
Tuyen. You need to ask yourself, do i what it to sound brilliant or just good enough. There is a lot you can do, but you need to really listen first and then based on its sound, develop a plan of attack. The 2.2uf 100 volt Duelund are perfect. I see there are Riken 2 watt resistors. Riken have a strong flavour and generally do not make a prefect choice for most applications, But they can fix out of tune parts combinations, because of there veiled dark grainless sweet character. But if you what perfection, they must go. Initially another resistor combination may sound worse, (2 watt Allen Bradley is a great first choice). But you will need think laterally, about the big picture. The other resistors look like 5 watt TRW or whatever. All 5 watt resistors I have heard are ordinary. Chuck them and run 2 watt Shinkoh or possibly even audionote 2 watt, (they could be interesting). Mount the shinkoh on the metal case with heat transfer paste, that will dissipate the extra heat into the metal case, because at 2 watts the shinkohs are underrated for this position. Look at the picture at the far right, that shinkoh is a 2 watt in a 5 watt position but by mounting it like that, it can take the extra heat and sound so much better than any 5 watt resistor. Black Gate Capacitors Have great strengths clean, clear, big sound stage, detail, but that means nothing to me, because they have very poor musical involvement, they have a sterile, unmusical quality, You need to get rid of them, and get some big Solen PBs and bolt them on where you can fit them. I see so many things to attack. You need an understanding of the sound of the parts you want to use, it's hard trial and error. Anyway it never ends, 
« Last Edit: March 27, 2014, 03:10:29 AM by stevenvalve »

Offline Tuyen

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Re: Tubelover 112a/26 DHT preamp
« Reply #2 on: March 27, 2014, 02:06:00 PM »
Thanks Steven.  I can start with those 2 things first. I have heaps of Solen PB caps sitting around that I can try instead of the blackgates.   Will need a bigger chassis though.       I will get some  shinkoh or audionotes (if shinkoh not available) to replace the rikens.

Any thoughts regarding replacing the Noble volume pot with an autoformer volume controller?   

Do you have any nice 112a or type 26 (ux-226, cx-326) tubes in your collection?  :D

Offline ochremoon

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Re: Tubelover 112a/26 DHT preamp
« Reply #3 on: March 27, 2014, 03:17:11 PM »
Tuyen, can you give us an idea how it sounds now, before any parts replacement? Then a commentary on how the sound changes with each change would be very enlightening.
Cheers,
Chris

Offline Jehuty

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Re: Tubelover 112a/26 DHT preamp
« Reply #4 on: March 27, 2014, 03:21:11 PM »
Do you have any nice 112a or type 26 (ux-226, cx-326) tubes in your collection?  :D
How much are you willing to pay?  :D

Any thoughts regarding replacing the Noble volume pot with an autoformer volume controller?   
Hedalfa got some very nice transformer volume controls for his KillerPre, perhaps he can chime in and tell us a bit more about it  :)
Not all that matters can be measured, not all that can be measured matters.

Offline stevenvalve

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Re: Tubelover 112a/26 DHT preamp
« Reply #5 on: March 27, 2014, 03:41:02 PM »
Thanks Steven.  I can start with those 2 things first. I have heaps of Solen PB caps sitting around that I can try instead of the blackgates.   Will need a bigger chassis though.       I will get some  shinkoh or audionotes (if shinkoh not available) to replace the rikens.

Any thoughts regarding replacing the Noble volume pot with an autoformer volume controller?   

Do you have any nice 112a or type 26 (ux-226, cx-326) tubes in your collection?  :D
Noble volume pots are carbon substrate I believe, and mid priced as are the Alps, but they have a very different sounds. The noble is slightly veiled  and dark, but musical and rich, plus it has the ability, because of its character to nullify problems, (a little like the rikens). Alps has a clean clear detailed sound, They are opposed. It's a good thing having these Ying and Yang volume controls, because at the finish of the rebuild, this is a handy trait. Personally I would dump both, and get something tasty, But Some stepped attenuates are junk, because of the poor resistor complement they use.

Offline stevenvalve

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Re: Tubelover 112a/26 DHT preamp
« Reply #6 on: March 27, 2014, 03:48:01 PM »
Tuyen, can you give us an idea how it sounds now, before any parts replacement? Then a commentary on how the sound changes with each change would be very enlightening.
Cheers,
Chris
This is a must. There is never a sure thing, combinations in synergy, that's what matters, and there is no guarantee.

Offline zenelectro

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Re: Tubelover 112a/26 DHT preamp
« Reply #7 on: March 27, 2014, 06:46:08 PM »
Steven, you should try the Rod C heater supplies and see what you think.

From what I can dig up, They are a pretty advanced type supply using constant current for filament.

Whether they will sound better is the question.

Offline stevenvalve

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Re: Tubelover 112a/26 DHT preamp
« Reply #8 on: March 27, 2014, 08:03:03 PM »
Well you know i am into less is more. Direct AC heaters have to me always sounded better. Real music has a warmth, so does direct AC but at a cost of noise. All the DC heaters i have heard sound cleaner but also clinical, But i have only heard a handfull, so they maybe good, but they are a complicated device, and that aspect does not fit my criteria of, Less is more.

Offline guru

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Re: Tubelover 112a/26 DHT preamp
« Reply #9 on: March 27, 2014, 11:49:04 PM »
sorry tuyen but the blackgates internally are fakes so you might start there as to mods.

Offline vitavoxdude

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Re: Tubelover 112a/26 DHT preamp
« Reply #10 on: March 28, 2014, 09:37:53 AM »
   :o :o :o :o Fake Blackgate caps in a preamp built by Tubelover in Indonesia.  I think I would like to challenge this.  How do you know Guru that this is so, do you have empirical evidence of such things?  We all know that the Chinese copy many circuits etc so as the caps are now highly priced it may be worth while doing.  Maybe the manufacturer is not aware of the deception, perhaps if it is proven this should be passed on to Tubelover.

We need to protect ourselves from such goings on if proven.  Please indulge us.

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: Tubelover 112a/26 DHT preamp
« Reply #11 on: March 28, 2014, 09:53:47 AM »
Are they famous? I know a lot of Indonesian manufacturers/DIYers but I only heard about them when Tuyen bought a preamp ages ago...
Not all that matters can be measured, not all that can be measured matters.

Offline Tuyen

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Re: Tubelover 112a/26 DHT preamp
« Reply #12 on: March 28, 2014, 02:20:07 PM »
Interesting!   Tell me more!    I've got quite a few blackgate caps in my stash of parts.  Would be interested to determine which are fake and which aren't.

Tubelover isn't famous globally.  But Arif is sort of known in the DIY community in Jakarta/Surabaya.


Regarding the Rod Coleman filament regs, are they what are used in the killerPre?  As Paul B mentioned, the ones he used were from the UK and schematics not published, which matches what I know about the coleman regs.

What sort of avc/tvc are used in the killerPre?

Will document and post my subjective thoughts as I experiment with this pre.  Hopefully it is of interest to some here.      Need more sharing of knowledge/experience on this forum!



Offline guru

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Re: Tubelover 112a/26 DHT preamp
« Reply #13 on: March 28, 2014, 02:32:48 PM »
Blackgate caps were manufactured by Rubycon to the Takeda Machinery specification and I purchased them directly from Takeda for the last 5 years of manufacture including the last shipment release. Every single cap I purchased of which there were several thousand, featured the "K" on the top of the cap, the expansion weak point so to speak. There was never any other pattern used. The double half moon pattern on the ones inside you amp form the bulk of the ebay variety now common and very fake.
Sorry to rain on the parade but given the price that these things sell for now, forgery is a very lucrative business. I still have many new Blackgates and non have the double half moon pattern.

Offline hedalfa

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Re: Tubelover 112a/26 DHT preamp
« Reply #14 on: March 28, 2014, 03:32:05 PM »
Blackgate caps were manufactured by Rubycon to the Takeda Machinery specification and I purchased them directly from Takeda for the last 5 years of manufacture including the last shipment release. Every single cap I purchased of which there were several thousand, featured the "K" on the top of the cap, the expansion weak point so to speak. There was never any other pattern used. The double half moon pattern on the ones inside you amp form the bulk of the ebay variety now common and very fake.
Sorry to rain on the parade but given the price that these things sell for now, forgery is a very lucrative business. I still have many new Blackgates and non have the double half moon pattern.

Not wanting a fake, yet the 64 dollar question is how does the fakes sound in comparison...


Offline zenelectro

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Re: Tubelover 112a/26 DHT preamp
« Reply #15 on: March 28, 2014, 03:36:24 PM »
Well you know i am into less is more. Direct AC heaters have to me always sounded better. Real music has a warmth, so does direct AC but at a cost of noise. All the DC heaters i have heard sound cleaner but also clinical, But i have only heard a handfull, so they maybe good, but they are a complicated device, and that aspect does not fit my criteria of, Less is more.

Yes - That is pretty much where it stands with me. However after a lot of work I did develop a better heater supply for indirectly heated triodes than AC.
It's a very tricky balance, as soon as you go DC heaters things clean up and you get the obvious tending towards lean washed out sound. However you can
have your cake and eat it with careful design, retaining most of the musicality but also getting the added resolution. 

Certainly for a system that needs musicality and richness AC heaters are a safe bet.

Z

Offline zenelectro

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Re: Tubelover 112a/26 DHT preamp
« Reply #16 on: March 28, 2014, 03:44:43 PM »
Blackgate caps were manufactured by Rubycon to the Takeda Machinery specification and I purchased them directly from Takeda for the last 5 years of manufacture including the last shipment release. Every single cap I purchased of which there were several thousand, featured the "K" on the top of the cap, the expansion weak point so to speak. There was never any other pattern used. The double half moon pattern on the ones inside you amp form the bulk of the ebay variety now common and very fake.
Sorry to rain on the parade but given the price that these things sell for now, forgery is a very lucrative business. I still have many new Blackgates and non have the double half moon pattern.

Good snoopin' Guru. I just checked all mine which are very old now and almost certainly authentic - all have the 'K' except for the NP's which have a plastic cover.

Z



Offline zenelectro

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Re: Tubelover 112a/26 DHT preamp
« Reply #17 on: March 28, 2014, 03:54:57 PM »
Not wanting a fake, yet the 64 dollar question is how does the fakes sound in comparison...

Probably better  ;D ;D ;D ;D

In all seriousness, opinions about capacitors are often a laugh a minute.
I know one place that was selling Rubycon 'ZL' ultra low impedance electro's as a Black Gate upgrade and their new premium cap.
On the other hand, I read a cap 'shootout' that rated the Rubycon ZL's as the worst of all.

Now the reality of the shootout was they had the ZL in parallel with a smaller cap and probably created a tank circuit which made it sound bad.
This can be especially the case with low impedance caps such as the ZL.

Moral of the story is, the cap is important but so is how you use it.

Z

Offline Tuyen

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Re: Tubelover 112a/26 DHT preamp
« Reply #18 on: March 28, 2014, 04:01:15 PM »
http://www.ebay.com/itm/1-pcs-NOS-BG-BLACK-GATE-capacitors-F-series-680-uF-mF-65volt-High-End-audio-NEW-/280874465418

Indonesia seller.  No 'K' on the top.

"I guarantee that these are genuine Black gate capacitors with 30 days money back guarantee"

Dodgey-ness!

Offline Tuyen

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Re: Tubelover 112a/26 DHT preamp
« Reply #19 on: March 28, 2014, 04:02:25 PM »