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New reissue KT88 versus vintage Genelex/Gec KT88

Posted by Michael Samra (D) on April 28, 2010 at 05:33:00

I know I know,you may have heard it all before but not really because I haven't seen much on comparison of the reissue kt88 vs old genelex kt88. Maybe its because tube dealers that sell both,don't want customers to assume any facsimile of the truth for fear of them expressing anger over a 400 dollar a piece sale price, and then being bested by a tube costing 50 to 70 dollars each.
When I test any new part, or amp, or preamp,anyone that knows me realizes that I don't depend on one thing for judging that component. The brain and human ear can always acclimate our feeling and hearing mechanisms to adjust to imbalance or inefficiencies the equipment or component may have. Being that our ears are not linear,we sometimes are off by a country mile in our subjective listening tests.
Getting to my comparison of the New vs NOS genelex kt88. Everyone knows the sonic virtues of the tubes of yesteryear.What some people don't know is,under biasing a tube and not putting at least 200 hours on a tube is not going to give you a valid interpretation of the tube's overall character.
Last night for the first time,I made a month long comparison between new versus vintage Genelex/Gec.When you under bias the reissue kt88, its going exhibit harshness and transient distortion like you have never heard. When you are generous with the bias,(and when I say generous,I don't mean 60ma),I mean like 80 to 85ma,this tube will rival and and soundly defeat the vintage Gens for sonic richness in the mids and upper high end. Bass is deep and controlled and very energetic,with all the basic flat response and low distortion you would get with a very expensive amp.You need to request the higher transconductance testing ones for audio
.The vintage Gen/Gec were also very detailed and had a tiny bit more focus on the very very top frequencies and I am talking tiny.After that,the reissues just took over. They were more three dimensional,more alive,richer in every part of the spectrum than the vintage was and,it had the sonic character of the vintage TS 6550 black plates.
I honestly think that being New Sensor makes the new tungsol and the new Genelex from original recipe,they were able to combine the sonic virtues of both tube types and came up with the master valve.
I did the test on my grommes 260a amps which have regulated screens and a higher plate voltage.This would give me a honest pentode type evaluation and from the distortion test,it made realize that many people are under running this tube because biasing at 58ma like grommes recommended,made the tube sag and distort in the upper octaves.Instead,I biased at 70ma,and the tubes were the best sounding kt88 I have heard to date,not counting the 6550 tungsol black plates..They are definitely much more alive sounding than their vintage GEN/GECcounterparts.
Just be sure to be generous with the bias because these tubes can take 90ma all day long at typical kt88 voltages.You will not hurt them,trust me. I finally feel that this is the most affluent tube in the industry other than maybe the Shuggie treasure series.I want to hear those again.When I put the sweep generator on from the computer RTA, I couldn't see any peaks or dips in the response. The only thing I had found in new versus old was,the reissues have a little more upper frequency distortion when they are not biased to at least 80 to 85ma.On the grommes and the audio research amps,you typically don't go that high because of the higher B+. Once that bias issue was corrected,I can't stop praising this tube.

"For every complex problem there is an answer that is clear, simple, and wrong" H. L. Mencken

Edits: 04/28/10 07/31/10

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