Monday, January 14, 2013

Tube Review: Genalex - Gold Lion B759 / 12AX7A

(Image from Google)

I'll admit right off the bat that I've never been a huge fan of small signal Russian tubes.  Overall they seem to have a "solid-state in a bottle" effect and certainly don't come close to some of the better NOS offerings from Mullard, Amperex, RCA, and company.  I would even prefer to spend my money on GE, Ei, Raytheons, or CBS tubes.

The other night I was given a chance to borrow a pair of re-issue Genalex B759 / 12AX7A tubes.  The boxes are certainly a nice copy of the original, as is the logo imprinted on the glass.  However, if you compare the "re-issue" to the original, they are in fact nothing alike.  Of course the machinery that made the original British tube is long gone.  It's a small point, but I never liked the use of the term "re-issue" which means, at least to me, that the product actually has some connection to the past.

Instead, the Genalex B759 looks like a Sovtek 12AX7LPS - the plate, mica, and layout are the same.  Perhaps there is some magic going on with the screens and cathode chemistry, but that's difficult to tell without breaking them and taking a look inside while doing a chemical analysis.  So one theory - these could be just highly selected and matched "super" Sovtek tubes.  Perhaps a softer vacuum could come into play.

Okay, enough intellectual yammering.  How does the tube sound?

My Quicksilver full-function uses a 12AX7 as the first tube in the phono section.  The linestage also has one.  I pulled out my 1960s short-plate Mullards and replaced them with the Genalex B759.  I had a fellow audiophile over to listen.  As we talk tubes and single-ended amps, we let the whole system warm up for a while before listening.  Hmm... this actually sounds better than I expected.  Yes, the Genalex tubes do sound different than the Mullards, but within the confines of this system, the B759s are completely acceptable.

The first word that comes to mind is fast - perhaps due to a bit of additional upper-midrange/lower-treble excitement.  This extra bit of zing makes music fun and engaging, all without sounding overly bright or with the type of "solid-state" grain I normally associate with many small signal Russian tubes.  Overall depth seemed a tad flatter than the Mullards, but the effect lessened the longer the preamplifier was on.  Coherency from the lowest to the highest octave was even handed, except for the already noted touch of forwardness.  "I could live with these" was one comment I made as Fleetwood Mac was spinning away.

So yes, the Genalex B759 / 12AX7A does deliver the goods, though I fear a more revealing speaker - like the UREI 813As - would show more limitations.  I suspect this tube may not be a good match for forward systems - especially ones using horn loudspeakers.  However, they would be a great match for some darker sounding gear like the Dynaco PAS or Eico HF-85 preamplifiers.  With the ever rising cost and increasing scarcity of decent NOS tubes, it is good to know that there are real alternatives out there.



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