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Sunday, October 4, 2015

The Ultimate Line Preamplifier

Hi!

Last year I was asked to build an ultimate line preamplifier which has the potential to even better the single ended 10Y preamp with silver transformers. But how to improve upon such a preamp which is pretty much maxed out already?




The single ended versions with silver use top notch transformers. So what is left to play with are the capacitors. But I think those ex military stock NOS paper in oil caps are extremely good and I prefer them stuff over the usual 'audiophile grade boutique caps'. So the idea came up to abandon all caps from the signal path and to go differential. A prototype version with copper transformers was built and proved to sound excellent.

But then the Elrog 300B came and with it the idea to use it in a line stage. Again a prototype with copper transformers was built first. For this a custom OPTVC was wound by Tribute. Again the sound was very good, but the 300Bs are a bit more microphonic than the 10Y and would require a more careful selection of tubes.

So finally the decision was made to go back to the differential concept and build it with the best possible parts, which means a whole bunch of silver:




Lundahl silver line output transformers and silver wound AVCs from Intactaudio. 3 Pairs of Lundahl LL7903Ag silver line input transformers will be wired for different step up ratios to provide the possibilities of different gain. Each of the 4 tubes has it's own plate choke which are also silver wound! So all parts which are involved with the signal path are silver wound. 14 transformers and chokes in total!

Of course for such a project only the finest tubes will be used. In this case a matched quad of the fabulous 1602, a special variant of the 10Y




So will this be the best line preamplifier in the world? There are many claims out there about the best this or the best that. This is highly subjective, especially in audio. No matter how much effort is spent, there might always be something better elsewhere. But based on my experience in audio and with tubes, parts and silver transformers, this will be the best I can currently think of. And of course I need to finish it first and give it a listen. Stay tuned!




Best regards

Thomas

13 comments:

  1. Yes, it is the best preamplifier in the world ! Sez the owner ;)
    Anyway, in my (treated) room, to my ears, in my system (all silver Thomas Mayer Elrog monos, Voxativ Pi speakers) the 1602 DIFF sounds better than everything else I tried (including Kondo Audio Note and 2 dozen other exotic brands.
    Thanks Thomas !
    Dan

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  2. Thanks Dan :-)
    Let's see how the silver version comes out...
    And of course the other special project which is in the works...

    Thomas

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  3. A wonder that there is no Push-Pull Power Amplifier by Thomas Meyer......

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    Replies
    1. Hi!
      I have built push pull amps in the past (before I had this blog) and will build again. As soon as someone commissions a Push Pull amp, I will build it. As time permits I will also build one as demo amp.

      Best regards

      Thomas

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  4. Hi Thomas,

    Have you already played with 11J7 tube. I head this one is a 'ultra-low-microphonic' version of 6J7 but it sound good? Could 11J7 be suitable for a preamp or as a driver for 2A3 amp to be paired with horns?

    Thanks!

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    Replies
    1. Hi!

      As far as I am aware the 11J7 is just a 6J7 but with 11V heater. Search for 6J7 circuits. There are plenty. You can use the 11J7 in those as well with change of heater supply. I never had any issue with microphonics using indirectly heated tubes in line stages except maybe very old triodes like globe 27. Und much less so in driver stages

      Thomas

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    2. Sorry, I said I head about low microphonics but in reality it was very low noise instead

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  5. Hi Thomas,

    Excited to see the build progress of this.. Just curious, have you tried 45's in a linestage in either SE or PP differential? Maybe with lower output power.. If you did, what did you think of it? Thank you.

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    Replies
    1. Hi Rick,

      yes I tried it in SE and surprisingly it was not very good

      Thomas

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    2. Hi Thomas,

      That's an interesting result for a linear DHT with relatively low Rp.. Thanks for sharing.

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    3. Hi!
      Obviously the requirements in a preamp are different from those of a power amp. Also son't focus too much just on the tube. The entire circuit is important. In a different circuit things might have turned out in favour of the 45

      Thomas

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    4. Hi Thomas,

      Thanks.. Yes, they sre superb as power output tubes, especially with a DHT front end, but I never heard 'em in a preamp applicaction. Yes, I agree the overall circuit is much more important and in the context of the whole system.

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