Quote:Question is, the original post is from November 2012. Do the designers read these forums at all? If so, why is the amplifier still claimed to be fully "EL84 compatible"?
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Excuse me for not being a fanboy, but I'll have to say this is just a huge omission on Decware's part.
I dunno. The fact that a couple of NOS tubes don't sound great doesn't strike me as any sort of glaring omission. And while the amp is obviously designed to work with the EL84, I did not see anything on the website that says "will sound great with every EL84 tube made." In fact, the website and Steve are quite plain that this amp will sound its best—by a wide margin—with the SV83, and he explains why.
Don't get me wrong, I understand your frustration. But just for fun, I threw a couple of JJ EL84 tubes in my ZS, and they worked just fine. Didn't sound great, but they weren't muffled and underpowered. They glowed and produced decent, if constrained sound, with a narrow perspective on the soundstage and somewhat hardened vocals and guitar, but nothing like the SV83 (granted, no break-in time, but obviously "working").
FWIW, I use my ZS as a center channel amp for a single ERR speaker. I played AIX BluRay discs of Rita Coolidge and Moonlight Acoustica for this little check. Signal tube was a National, rectifier is the Phillips of which Upscale is making such a fuss.