Cautionary tale about KT 88 tubes

[Steve]

Yes, as Simon mentions above, I also had some negative experiences with KT88's. Went through a number of sets of them when I had Jadis JA80's. 2 sets sourced through Jadis and a set of JJ-T's. Moved to KT120's and found much better reliability. Lost that feeling of "which tube is gonna blow now" when switching on the amps.. And a much firmer, upfront presentation with the KT120's. Perhaps traded a little bit of sweetness for better transparency.
Currently using Winged C 6550c's. Really happy with their presentation.Beautiful mids and top end,a holographic view that I hadn't experienced with previous tubes. To be fair, not really comparing apples with apples as they're in JA200's as opposed to my earlier JA80's. No reliability issues thus far.. Hopefully won't come back to haunt me as certainly seem a little on the expensive side to replace now..
I think a number of valve amp manufacturers are steering clear of KT88's now. Jadis mentioned same when I contacted them a while back.
Would be interested to hear what you settle with Peter..

[PeterK]

Thanks to everybody for their advise and suggestions. Its been quite a strange week. I took the amp out to Bernard, Cloneys go to man for tube amps, and after testing it appears that the amp is fine, no burnt out resistors or capacitors, all wiring looking good, so it seems that the tubes are the problem. The 2 Gold Lion tubes at V3 and V4 were fine, but the tubes at V1 and V2 were displaying very very low emissions, so we these out for the tubes in V3 and V4, perfect, so a tube problem.

So I went to Watford Valves to look for advise on tube type etc. to be met by the rudest and most arrogant person, certainly no sales man. Whether he was just annoyed I had bought from another firm I couldn't tell or that I was Irish, but he didn't want to hear my story at all. As far as he was concerned it was not the tubes, there was no such thing as low emissions, it was the amplifier and the they were not biased correctly. He said go back to your original supplier and see what they say. He did not want to discuss anything at all including Airtights views on KT 88S.

So the next day I sent the Gold Lions to be replaced, we will see!!

Then in a rush of blood to the head I ordered a matched quad set of Psvane KT 88s treasures from Germany, bloody expensive too. I worry that they are manufactured in China but we'll see. Thanks aDiesel.

Also many thanks to Bernard for looking at the amp. The Psvane tubes are due to arrive next Wednesday so hopefully I will have an update next Saturday.

[sdiesel77]

You shouldn't be disappointed with the Psvane ;)

[PeterK]

New tubes are in since Wednesday, a matched quad set of KT 88s on foot sdiesel's recommendation, nice turntable and video too.

They sound terrific but I think need running in. I am getting a very slight electrical humming noise through my left 2805, and I swapped cables but hum stayed put, so not the amp. Weird, probably a sign that all is not well with the Quads. Bias on tubes is pretty steady. Hopefully they will last longer than the Gold Lions.

Thanks to all for their advice, any thoughts on the Quad speaker problem, it seems to be intermittent.

[Ivor]

New tubes are in since Wednesday, a matched quad set of KT 88s on foot sdiesel's recommendation, nice turntable and video too.

They sound terrific but I think need running in. I am getting a very slight electrical humming noise through my left 2805, and I swapped cables but hum stayed put, so not the amp. Weird, probably a sign that all is not well with the Quads. Bias on tubes is pretty steady. Hopefully they will last longer than the Gold Lions.

Thanks to all for their advice, any thoughts on the Quad speaker problem, it seems to be intermittent.

Quads can be temperamental buggers. If not used or powered up for a while they can take quite some time to come "on song" again. Assuming it's not panal damage of any kind give them a few days to sort themselves out.