Best KT88 valve?

[Wakefield Turntables]

Well after playing around with some 6SL7's I'm now thinking about the Quad of KT88's I have sitting in my Sondex. I'm not sure what they are! But, recommendations for replacements would be most welcome. Is there a universally accepted holy grail of KT88's?

[spendorman]

What about the GE 6550 and 6550A?

[daytona600]

Not Cheap but these sound Fab EAT KT88



“Sonically the results are absolutely superb, trouncing generally available examples and bettering even NOS MO samples (which will cost you rather more than EATs). Romantic they aren’t, but if you want power, transparency, grip, focus, detail and definition – all woven into a singularly convincing whole, then look no further. What’s more, with KT88s (and the 6550 equivalents) generally being used in multiple arrays, quality and matching becomes even more important to an amplifier’s overall performance. Consistency and longevity appear good, with no failures so far (and we’ve tried!) which combined with the fantastic musical and sonic performance makes these valves a must own upgrade for everyone with an appropriate amplifier. Once again, they seem expensive until you hear the results, at which point purchase becomes a no-brainer.” Roy Gregory, HiFi+ - Product Of The Year Award

[User211]

They do sound incredible and I think it is probably the best sounding KT88 ever made.

It was the Tesla KT88. Unless the filaments have changed expect reliability problems. Loads failed on me.

It was so far ahead of anything else it was a joke. Tung-Sol NOS 6550 next best in Air Tight ATM2. Big gap Tesla way ahead of even that.

[User211]

BTW I also tried quads of:

GE 6550
JJ KT88
Sovtek KT88
Some Chinese Art KT88

JJs not too bad, which is what Quad use. The Teslas were a lot more reliable in lower powered amps with gentle switch on.

If you can get a guarantee on the EATs of return all to sender if one of the set fails, and you can cope with EATs absurd price rise on them... in other words, forget them, TBH. Crying shame. Fantastic sonics. Seriously upset me as I watched quite a few (actually I can't remember the precise number but all with the 6 month warranty) fail on me before I gave up. They failed quite quickly - within a few months.

Amp was fine - no failures AT ALL with other types.

Might be worth a Google to see if the EATs are failing. If they aren't, something has probably changed. In which case the sonics may have too.

NOS GEC may be the best option but rare and expensive. I still think the EAT will sound appreciably better than even that IF it is unchanged from the Tesla spec.

Personal preference in tube rolling is an element, but the Teslas were so far ahead, and from all accounts the EATs seem to be too. You'd need to be a bit deaf or warped not to prefer it over other also rans. No matter the circuit I suspect.

The Teslas were £80 each, LOL. Check the EAT price:D. Absolute Sounds:D

[Wakefield Turntables]

Sounds like GE or Tesla then. I'll have to check out what my USA based suppliers have in stock.

[User211]

The Tesla are no more - they are only available as EAT now.

[nickbaba]

GEC KT88

I got a quad together from ebay over a few months, not too expensive, all NOS condition, lots available, just shop carefully, buyer beware!

[User211]

GEC KT88

I got a quad together from ebay over a few months, not too expensive, all NOS condition, lots available, just shop carefully, buyer beware!
As a NOS matched quad, though, expensive.

Sneek pot shotting can pay off well though, as you say.

[User211]

Had to post this. Ken and Rob are right, though I discovered them well before they did LOL.

I am seriously thinking of getting some EAT 300B for my DAC, in memory of how fab these KT88s were. 12 month warranty on them from EAT at the mo. I figure the 300Bs may well survive in my DAC.

The EAT KT88s despite their outrageous price are so exceptional that even the usually reticent Ken Kessler had this to say.

"The EATs are sensational. Even though the measurements indicate no gain in power, the sound is more robust, with convincing weight and palpable mass, but the real gains were in the midband, the EATs increased intimacy strengthening the sensation of the singer being in the room. The extra clarity and openness make it much easier to focus on detail typically masked or overwhelmed by louder sounds. Then, there's the attack & decay capabilities of the EATs, they're quick, almost ridiculously so. Put on a disc by any virtuoso known for rapid plucking or fingering, no muddle, no delays, no upsetting the timing. What we have here, my friends, is the valve amp equivalent of Viagra."
– Ken Kessler, HiFi News

Roy Gregory loved EAT KT88s so much he awarded them HiFi+'s coveted Product of the Year!

"Sonically the results are absolutely superb, trouncing generally available examples and bettering even NOS tubes. Romantic they aren't, but if you want power, transparency, grip, focus, detail and definition, all woven into a singularly convincing whole, then look no further."
– Roy Gregory, HiFi+

[Wakefield Turntables]

You can still buy EAT KT88 but prices seem to vary from $350-750 :eek: per valve. I think I'll try the GEC KT88's.

[montesquieu]

The best 'affordable' KT88s were Svetlana Winged Cs - I never felt the need to go to anything more exotic.

I'm running KT90s at the moment in the big Radford (needed a bit of tweaking by Valvebloke) I have two Winged C KT88s in the box patiently awaiting aother NOS pair becoming available. Very thin on the ground these day. But I think I'd keep them in reserve even if found as I do rather like the KT90s.

It seems to me like most modern production KT88s are either not very robust, or not very good sounding - hard to find anything that's both. (To be fair I haven't tried the EATs which are nevertheless probably rightly tagged as 'best'). Some people do seem to recommend the Golden Lion KT88s as a decent, modern production all round compromise, I've had decent results with these too.

[Wakefield Turntables]

i thought about kt90s I suppose it stops having to worry about the best of the KT88s. The main contenders seem to be EAT, GEC, Svetlana winged C's Tesla. I'm not paying EAT prices, so I'll just have to do a little more research and bite the bullet at some point.

[User211]

It seems to me like most modern production KT88s are either not very robust, or not very good sounding - hard to find anything that's both. (To be fair I haven't tried the EATs which are nevertheless probably rightly tagged as 'best'). Some people do seem to recommend the Golden Lion KT88s as a decent, modern production all round compromise, I've had decent results with these too.

The Svet Winged C was well rated by many.

But basically, I agree with your summation. And it is a shame, as it can sound very good when done right.

A couple of EAT 300Bs look to be around a similar price to KR equivs. The KR 300B is defo great in my DAC as I have tried it. I'm going to e-mail EAT now. Been reading some reviews and one guy on Head-Fi is amazed by the EATs. I'm sucker enough to believe him LOL.

[JohnJo]

Pretty apt thread for me as I have been valve (and amp) rolling today.

I've tried Sovtek and Gold Lion KT88s, GL KT77s, JJ EL34s as alternatives to the KT120s that came in my Prima Luna amp.

Each have their strengths but Sovtek suits my set up best.

Problem is I have only pairs rather than quads of some so a bit of mono fiddling required!

Think I'll phone Anthony of Tube Distinctions as he has a whole web page about KT88s and seems to be "the man" on these.

http://i1229.photobucket.com/albums/ee462/castle48/Lockwoods/85CF33ED-DB77-4165-BEE5-5037A50B5D52.jpg (http://s1229.photobucket.com/user/castle48/media/Lockwoods/85CF33ED-DB77-4165-BEE5-5037A50B5D52.jpg.html)

[StanleyB]

Is there a universally accepted holy grail of KT88's?
My money is on the MOV version. Enjoyed them in one of the Baird amps (or was it VTA?) many moons ago.

[anthonyTD]

Best over all KT88's ever produced undoubtably were, and still are' the original GEC KT88, single or triple getter versions, both are excellent in Sonics, and longevity!
As for the EAT KT88's, it is true, they do have an incredible sonic presentation, even when comparing with the GEC, however; they were plagued by reliability issues due mainly to poor cathode to heater insulation problems. The valve in question was made by the original Tesla factory before it closed its doors in the early 2000's, they had decided years before, that making Audio valves was not profitable any more, and they were to concentrate on making, and producing valves for broadcasting/transmitting etc, they soon realised their mistake, and tried once again to make certain audio types [including the KT88] but according to the grapevine at the time, they had lost machinery, and the technical personnel that knew how to do certain processes that were key to making certain types of valves, hence their demise, its a shame because if they had persevered,
I am sure they could have sorted the issues. EAT [Apparently] purchased all the stock they produced, and re-branded them up, but also [again apparently] cryo treated them, I still have about half a dozen of the valve with the original Tesla logo on.
I dealt with Jozefina in the very beginning, and even promoted the EAT KT88 in my own equipment, there was also talk of me becoming the UK distributor, but the amount of stock I would have had to purchase was too much to take on at the time, so it was later offered to Absolute Sounds, and the rest as they say is history.
Even early on, I would have to reject at least 10% of the stock I was sent due to heater to cathode insulation issues, and eventually, I stopped stocking them all together, due to this.
I then Went back to using my second all time favourite, the original Svetlana Winged C, although it didn’t have all the magic of the EAT, it was a much more reliable valve.
Sadly now the original winged C's are no more.
Anthony,TD...

[User211]

No reply thus far from Jozefina regarding the EAT 300B. Virtually nowhere seems to sell them.

[mac72]

I wouldn't spend on power tubes more than £300-400 , you would be better off investing in signal tubes .
I've tried famous GEC and yes they're good but not worth paying double/triple/quadruple standard KT88 price , especially if you don't have a tester to check what they like.
If your amp takes 6550 you should try Svetlana 6550 , could be found in US for £300 , KT88 of said manufacturer is not but idea neither.
I don't think anyone mentioned Chinese valves , some are really good and reliable when sourced from a proper dealer ,
I have used 3 quads if Shuguang Black Treasure KT88 , had trouble only once when bought on Ebay from guy in Hong Kong, since then I used Grant Fidelity in Canada with no trouble , they cost $299 plus duty if you're unlucky.
Last month I bought in UK Shuguang tubes with clear glass , they seem to have same internal built and sound good , didn't have time to compare with smoked glass as time is in limited supply.
EAT tubes are really good but reliability is problematic , used them for a month or so till one fried one channel amplifier board , it set me back few hundred quid , I definitely won't go there anymore , they sounded really good though ��.
Slav

[Wakefield Turntables]

Thanks for the replies. I think I'm turning my back on KT88's and will be upgrading my valve power amp next years to something KT120 based.