WA2 owner. Been blown away for the past couple of months using a pair of Telefunken ECC801s as my driver tubes. You'll of course need 12AT7 to 6922/E88CC adapters. Great synergy with my GEC 6AS7G's power and Marconi U709 rectifiers.
Along those lines I've read that GEC A2900's are the absolute premier 12AT7 type tube...but that it has a higher amplification factor than others in the family. Has anyone here tried them with the WA2? Are they compatible or might they cause damage to the WA2 ???
Would appreciate any input.
http://tdsl.duncanamps.com/pdf/a2900.pdf
Along those lines I've read that GEC A2900's are the absolute premier 12AT7 type tube...but that it has a higher amplification factor than others in the family. Has anyone here tried them with the WA2? Are they compatible or might they cause damage to the WA2 ???
Would appreciate any input.
http://tdsl.duncanamps.com/pdf/a2900.pdf
I'm no expert but a skim read of the datasheet seems to answer your questions...
It looks to be a long life tube, a switching tube perhaps, due to the positive grid voltage characteristic curves.
Not intended for use where microphony is an issue.
I'd say that it isnt the pinnacle of 12AT7 in any way.
It looks to be a long life tube, a switching tube perhaps, due to the positive grid voltage characteristic curves.
Not intended for use where microphony is an issue.
I'd say that it isnt the pinnacle of 12AT7 in any way.
In tube lore, the GEC A2900 enjoys the reputation as one of the best of the 12at7 types. I have a phono preamp that i have used the a2900. It sounded just as good as the ecc801s. Its rarity and pedigree makes it highly coveted.
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That may be true, but quite a lot of Lore is quackery, snake oil....in my limited experience I'd guess that the a2900 is framegrid?
Using a tube not designed for low microphony as a phono preamp seems very likely to bring out the worst of any acoustic feedback that can occur. Another source, along with the whole vinyl media, and stylus/cart/platter.
I don't think the datasheet mentions frame grid, although that is not conclusive. It just says that it is reliable and has the two triodes well matched, while warning about microphony. A good valve to use in a computer, but not perhaps for audio?
Why do you say "tube lore" is quakery or snake oil". If you just want to create controversy here is what Brent Jesse of AUDIOTUBES.COM has to say of the A2900.
The even scarcer A2900 is in the "Gold Monarch" series by Genalex. Genalex was the premium line of tubes produced by the Marconi-Osram Company in England. It has wide, flat black plates and white lettering on the glass, the words "Gold Monarch" in white script, with the red Genalex decal logo around the top of the tube. There is also a British domestic version with the grey and blue GEC decal on the glass, that was not exported. These are true audiophile tubes, with tightly controlled noise specs, designed with audio perfection in mind. Any scarcer and these would be museum pieces!
I would maintain that as a well known vintage tube seller he has first hand experience with "tube lore".
I don't recall seeing any specification for noise in the datasheet, so how can it be "tightly controlled"? Perhaps the long-life cathode coincidentally has low noise too? It certainly was not "designed wth audio perfection in mind"; on the contrary, I suspect that audio performance was not even considered when this valve was designed.
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