I am in the planning stages for building a new amp and I need recommendations on current KT88 tubes. Has anyone had experience with EH, JJ, Sovtek or any other that they would recommend?
New Sensor's Saratov, Russia, plant makes 2 variants that are (IMO) your best bet. The EH labeled tube is the less costly of the pair, while the GEC "reissue" would be rated quite good, in any era.
JJ's Octal based production has been, at best, inconsistent, while Chinese KT88s of recent manufacture are GARBAGE. If it were possible to buy older Chinese production, with a degree of certainty, they would not be a poor selection.
JJ's Octal based production has been, at best, inconsistent, while Chinese KT88s of recent manufacture are GARBAGE. If it were possible to buy older Chinese production, with a degree of certainty, they would not be a poor selection.
I've had some minor consistency problems with EH KT88, nothing major, but as a consequence I would strongly recommend you get them from someone like Jim McShane who tests, matches and burns them in at real world voltages and currents.. This should all but eliminate the early failures, and not too many vendors do this.
Date code indicates 23 week of 1987, so these are older production "Golden Dragon." (PM Components?? IIRC) I am unfortunately quite familiar with these, and while they sound quite good, reliable is not a word I would use in conjunction with them. Best used at voltages not much higher than 400V and may 60mA plate current. I repaired more than a few ARC (M100) amplifiers after these tubes blew up in them.
kevinkr said:
Kevin: Thanks for the info! I suppose you could have said "the only thing reliable about them is their unreliability". 😀 They came in Red/Black Gold Lion Boxes. I've run a couple in my Quicksilver Mini Mites and thought they sounded quite good, although I prefer EL34's in the Quickies.
I recently picked up a nice used quad of the Genelex Gold Lion Reissues, so I am planning on selling these tubes for cheap if folks want to use them for amp testing, etc.
For my new amp, I have a pair of EH KT88's arriving tomorrow from Jim McShane. I've heard nothing but good things about the EH's when purchased from someone reputable like Jim.
Thanks for the input, I think I will go with the EH KT88's. Probably order them from Jim McShane. Still a few weeks from making the final determination.
JJ KT88's internal short/fail?
About a year ago, I purchased a matched pair of JJ KT88s from Triode Electronics. About two weeks ago, I noticed the inside of one tube glowing brilliant white. Looking inside more closely, the grids were glowing white. I swapped the tube positions, and the problem moved ... so I know the tube is suspect.
Grid bias set for cathode at 1 volt. Basically a stock amp but with the filter cap board upgrade from Triode and a silicon diode replacing the selenium. All PS voltages are at spec.
How often do JJ KT88 tubes have this kind of failure? I wrote to Triode but do not have a reply yet.
I did not physically remove the ancient can electrolytic in-view. But, it's disconnected.
Thanks.
About a year ago, I purchased a matched pair of JJ KT88s from Triode Electronics. About two weeks ago, I noticed the inside of one tube glowing brilliant white. Looking inside more closely, the grids were glowing white. I swapped the tube positions, and the problem moved ... so I know the tube is suspect.
Grid bias set for cathode at 1 volt. Basically a stock amp but with the filter cap board upgrade from Triode and a silicon diode replacing the selenium. All PS voltages are at spec.
How often do JJ KT88 tubes have this kind of failure? I wrote to Triode but do not have a reply yet.
I did not physically remove the ancient can electrolytic in-view. But, it's disconnected.
Thanks.
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