[mg2c]

Hi
I am using a Triode amp (Unison Triode 20) to drive my Stax earphones. It uses NOS German EL34 tubes in the power stage. These are still in very good shape, but two tubes in the "preamp stage" are defective and need to be replaced. This stage uses a combination of 1x ECC83 and 2x ECC82 - as far, as I understand, that's kind of a "classic" setup.
Mind helping me in commenting on the the tubes, I can choose from as replacement:

For the ECC83 part, I could choose from (writing down all I can spot on the tubes...)

• Philips JAN 12AX7WA 8726 AHA
• General Electric JAN 5751 87-48 33173
• JG-5751WA G.E. triple mica, D-Getter, blackplate
• Philips JAN 5751 USA

For the ECC82, I could choose from

• Philips JAN 6189W 34167 USA 8752AEE
• Brimar 12AU7 - I can see "Made in England" on the back, one of the tubes shows a print "2G (unreadable letter) / 3987"
• 6189 General Electric GE / USA

Eventually, I could get my hands on Philips "Miniwatt" ECC82/83, but I have no further information than just this "rough" desciption.

Mind commenting on your experiences with the quality and "sound characteristics" of these tubes? Thanks!

 

[DenverW]

Quick questions before a recommendation: are you also able to use 12at7 (same pin out with gain between the ax7 and au7) and how much of a factor is price?

 

[mg2c]

are you also able to use 12at7

Not sure, whether I can properly answer that. I know about interchangeability of certain tube "families", as you can see in my listing. As long, as "electrical values" are the same, I have no problem in using lower gain tubes. That actually would be an advantage, since the line sources I use (for example Linn Klimax DS) do provide such a "hot" signal, that volume for normal listening needs to be in the 8 o'clock region, 9 o'clock is already decently loud.
So any suggestion - also pricey ones - are welcome!

 

[DenverW]

The reason I asked is for stax estats I personally would avoid clear or treble bright tubes such as an rca clear top.

I would look for tubes that could add a little bit of flavor and lushness to the sound, and mullard or amperex might be good solutions. The reason I ask about the 12at7 is because you can find the very excellent mullard 10M tube as a 12at7 at reasonable prices. There are versions for au7 (pricey) and ax7 (super pricey!) as well. Other 12au7 (ecc82) options that I would recommend aside from mullard, brimar, or amperex would be telefunken smooth plates (semi pricey).

Another alternative would be an adapter from 12au7 to 6sn7, which opens up a whole new line of fun tubes. Rca grey glass, Ken rad vt-231 (more bass!) or some sylvania options are all great choices. Adapters are cheap, I get mine from xulingmrs on eBay.

Hope this helps, let me know if you have more questions!