Genelex Gold Lion KT-88 reissued tubes

Any tube can go bad any time -- this is not hot news. However, vacuum tubes were once the ONLY electronic valve available -- and for the most part delivered service with the same reliability as transistors -- and, believe it or not, often the same longevity.

Of the modern manufacture power tubes, the reissue Gold Lions, Pentas (Shuguang) and S.E.D. (formerly Svetlana) KT88's all provide remarkable levels of sonic performance, though still short of the best vintage tubes. In terms of reliability, only the Electro Harmonix seemed to have continuing problems. McIntosh recently dropped them in favor of the S.E.D for their OEM KT88.

Of the current manufacture KT88's, only two have the air and sparkle of the vintage Genalex/GEC KT88's from the UK ($800 -- $1400/quad): the E.A.T.'s ($1600/quad) and the new Shuguang Treasure Series Premium Grade ($350/quad -- $650/quad depending who you buy them from). I've not heard the E.A.T.'s but I have the Shuguangs and they equal my NOS Gold Lions sonically. Now let's see how long they last ;--)
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I just replaced my (8)EH KT88's in my Cary 120S amp with 8 Grade A Shuguang Black Treasures and also replaced the 2 driver and 2 input 6sn7's with Shuguang Black Treasure CV181Z's. The amp sounded very good with the EH tubes but the Treasures redefined this little Cary. Every aspect of the audio performance has been elevated to levels I thought were impossible. The tubes have about 90 hours on them and I am told they will improve with more hours. My Preamp is the Cary SLP 03. I have TJ Full Music 12AU7's coming and can't wait to try them out (EH 12AU7 replacements) The speakers are Harbeth Compact 7ES3. After 40 some odd years it seems like just maybe the SEARCH is over. I can honestly say the Shuguang tubes have been the single largest improvement I have ever made in any of my many audio systems over the years. Dave Hubbard

I also changed to the Shuguang (but not the Black Treasure) and have been very happy with them. Had them several months now. No more Genelex.

I run a pair of Sonic Frontiers SFM-160s which each use a MQ of GL KT-88s. The amps were bought used, then shipped directly to Chris Johnson for a comprehensive check-up and his SE+ mod. The GL KT-88s were "standard" issue for the SE+ mod.

That was two years ago. Since then, I have lost three GLs on three separate occasions, each time taking with it passive parts in the amp. The most recent episode was 90 days ago. I retubed withe MQ from Chris J when I had the amp repaired (locally). So far so good, but I am getting nervous (and broke).

Chris J would like me to consider the Tung Sol KT-120. He told me that the KT-120s are more reliable, the power transformer of the SFM-160 has more than ample current reserve to handle the 0.8 A increase in filament current draw and the KT-120s can take the punishment the SFM-160 delivers.

However, though still very premature, I have received mixed and even a few negative comments on this tube.

Any comments on the KT-120? Other quality options for 6550/KT-88 amps?

Thanks.

Flyfish2002, First, consider that the KT120 has only just recently hit the market. Other than its rating there is little to substantiate a recommendation for 'reliability'. But, the spec's are impressive and I can understand why Chris would recommend them as an alternative.

FWIW, I have some SFM's in my attic which I purchased used. The previous owner had problems with tubes in it (he was using KT88's not know for stability) and gave up out of frustration. I used SED 6550's - had no problems until I plugged in a 'rugged' KT88 and one went and took out a cathode resistor. I had it repaired and recapped - after which I lost one of my SED 6550's in one. Now they just sits in the 'attic' - I need neither the power nor the hassle of hauling it to the techie.

I'm not dis'ing these amps, they sound fine, its just that they were designed around a very rugged tube (EI KT99), which haven't been available for a long time, that could handle the very high plate voltage of these amps (650 as I recall - read your manual for exact specs).

FWIW.