Monday, February 1, 2010

Yeah, but what is THE BEST?

I still get this question... not "what is your favorite?", but "what is the best?"....this question is very funny to me.... Is there a best car? best wine? nah.. of course not... it is flavors... tastes.... I can measure distortion, but distortion doesn't measure sound.

I have been working on an amplifier for a dear friend for a very long time.. in fact, too long.. I really want to get the tone and gain correct, as it has to travel to the opposite side of the earth. I do not have the luxury of being able to simply ride my bike across town to roll some tubes, change the operating points, or swap nickel for amorphous on this one. So, back to best.. what is best? In this case, I know the listener.. George and I trade music. He has sent me everything from chamber quartets to Radiohead. He needs to play loud without congestion and yet play softly with emotion. So, what does George need?

The output tube is clean, clear, beautiful. It is an Eimac. I have tried quite a few different drivers. I thought I had it with the lowly and ancient Sparton/Cardon 484/485. The mids and up were delicate, transparent... incredible, really. However, when I compared to the 112a ->75tl amp, it was just a little lean in the midbass... and I mean just a little... perhaps the perfect setup for female vocalists and acoustic guitars...

Since then I have been on a tear. I have tried a new driver stage every other day for weeks. I thought, hey, add a 46, it has big tone. The tone was better, but the gain was way too high.. that slightly "jumpy" sound... so I dropped the input tube to a mesh 27... too wimpy and cloudy.... so in went a cccs and teflon cap.. the 46 was still loaded by a nickel interstage transformer... still a bit soft.. opaque... shouldn't be, but it was... next came solid plate and perforated plate 27's... a BIG step in the right direction... very close.. I listened to this for a few days to really get a feel for it.. Tonality was great, but in the end, just too much between you and the music... one layer too many.. but very, very good..

so then I yanked the output tube.. listened to 27 -> 46... but it didn't have that Eimac clarity.. good tone.. maybe enough gain.. but not it... so I scaled all the way back.. I listened to the output tube driven directly from my 71A linestage.. a spud amp.. what a reality check.. it showed just how sweet and detailed the sound could be... but nowhere near enough gain... and back to the ever so slightly lean tone of the original setup...

after a day of this, it finally came to me - the Aa.. an ancient German directly heated triode that is typically manufactured by Valvo or Seimens... this was one of those first notes kind of change.... by that I mean the first notes made me smile ear to ear... literally thirty seconds in I was marveling at some serious Coltrane sax work.. as if somehow faster than real... big, bold... and the impression is holding up... I think I have found the sound for George... his flavor... and I think my flavor, also...


  1. How 'bout 56->46 for better clarity? But it still might not possess the sweetness you are after. Always enjoyed the globe 56 over any variety of the 27.

  2. Hey JJ,
    How are you coupling the Aa to the Eimac? CCS / Cap / Grid choke?
    Do you need any more (Aa, not AA) btw? PM me if you do...

  3. Hey Joe (I never tire of typing that)....

    totally agreed on the 56 vs 27... I think the 485 is right there with the 56... but it puts me back in the way too much gain category...

    and CV, direct coupling.. stacked supply... no cathode resistor... nickel plate choke on Aa... still not wanting to mess with it.. sounding better by the hour.. :^)


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