Kt88

I have Quad II forties (which i really like) and am considering replacing the standard quad valves, but is there a valve that gives a significantly better sound, and in what respects would the sound be better?
A quick review of the retail sector shows that the cost of a matched-4 vary from a few pounds to a few hundred (e.g. GEC)
There are claims that cryogenic treatment brings improvement, and valves made in china especially suguang KT88-98 have a better sound than russian made equivalents.

What is the evidence for this?

Finally, someone suggested giving some an audition. This is a great idea, but how would i arrange this?

 

Firstly I'd be inclined to find out the original manufacturer of the Quad valves so that you don't end up buying more of the same!

Others may have more experience, but I guess it's down to trying them out. Lots of people recommend Svetlana's, but when I went from them to Electro Harmonix I have to say I much preferred the EH - much sweeter smoother sound to my ears, and only about £45 for a matched quad. I don't know if the Chinese valves have improved, but when I researched KT88 flavours I got the impression that at least some of the Chinese valves had reliability issues confused: ).

 

Sound advice - many thanks for the observation about the Electro's - the price is more attractive than the GEC at x10!
I've heard that Quad's own have a Russian origin, but I need to verify this.

 

The Tungsol 6550 reissue are highly recomended, around 150 euros a matched quad...

 

The sound of valves in any given amp is heavily dependant on the circuit design and the quality/ condition of the output transformers. The Quad is a famously unique design and a tube that sounds great in my amps, say, may be nothing special in the Quads.

I would not myself go for NOS GEC KT88s unless you have a burning need to lighten your bank account. There are five or six high quality new manufacture KT88 types available these days. The Quad II is manufactured in China now, so I would guess the stock tubes are all now Chinese.

I would actually contact Quad themselves and ask for their recommendations.

 

JJ is good

 

Interesting paradox here: couple of folks have said that Quad tubes are Svetlana/SED/winged C made in Russia - but now Quad have a new parent company in China, this may be different. Does this bring me back to the Suguang?

Has anyone auditioned valves - suppose i wanted to try the GEC's, can `i get a set on a sale-or-return basis to try them? What have other folks done when trying new tubes?

 

I know someone who has supplied Quad with Yugoslavian KT66s and KT88s

for KT88 go for winged C -or look for used GE 6550

 

If you mean EI (Nis) factory (recently sold to WE), this is indeed a very interesting info as I haven't been aware they have ever produced KT66s. They are famous for KT90 they supplied many respected manufacturers with, Jadis, Manley, etc included.

 

this was told to me about 2 years ago. I was asking what KT66s Quad now use in their Quad II amps and found this out. It may have changed since.

 

I've checked this, it's an incorrect information. EI is still producing one of the most respected KT90 valves (that go to Jadis, Manley etc) but they have never had neither 66 nor 88 variety.

Btw the factory is now bought by the mighty WE and their plan is to revive the old 300B there.

Best wishes, G.

 

PM Components got it wrong then.

 

Tesla KT88's are nice. A match quad cost ~ £110 a couple of years ago.
I found them smoother than Svetlana's and suited my circuitry better. The Tesla's balanced and stayed perfectly on balance (when checked a year later). The Svet's used to drift and eat my Power Circuit Board active components for some reason.

If you live near the Hants/Berks/Surrey borders you could audition mine...

 

if tesla = JJ than this is far too much money, they are around 110E at most of european tube vendors for a matched quad. if sourced direct from slovakia than maximum is 80E. check ebay for jj KT 88, if there's an auction you can get them even cheaper.
just take care you choose a colour you can live with. i actually find both appalling in a way - both blue and red - but who cares anyway.