6550 or KT88 ?

My Cayin KT88 had originally Shungyang tubes. Good, but nothing special. I tried the Sovteks KT88s and they were lifeless and thin sounding. I tried the Electro Harmonix and they were a mediocre match, too much treble and not enough bass. The were very powerful though.
Then I got me the Tungsol 6550 reissues. They clearly outperform anything else, and this is what I am using. In triode mode for classical and ultralinear for Jazz and Rock music. I suppose they would be a good match for your amp as well.

Thanks! - the conclusion seems to be that 6550 is not less musical :-)

Maybe the idea (Jtimothya) to try tube rolling the 5751 and 6FQ7 is a better way...

For the time beeing I have JAN GE 5751 (new production I guess) and RCA 6FQ7 (Brasil, red color letters)

Comments on these driver tubes?

Ole

Atomickid: where did you buy the Tungsols from?

Here you go.....here is a current Ebay Buy-It-NOW from the seller I went thru :

4 Matched Tung-Sol 6550 Reissue tubes,NEW
Item number: 5855636196 Buy It Now price: US $103.38

Shipping is $6 bucks. I got mine in ONE day priority mail.
This guy (Jason) is VERY good...I have bought from him three or four times, very trustworthy, always prompt, good product.

Good Luck!....best money I ever spent. Hey, if you don't
want the 6550's, drop me a line & I'll take 'em as a backup.
My guess is you won't want to, tho!

Hi

This is my first thread on this forum though I have been lurking around for sometime now.

Psam, I too have the Cayin kt88 amp. Given that you have changed the output tubes so many times, how easy is it to bias the amplifier? I am planning to bias the amp over the coming weekend. Are there any issues you have faced when biasing? One doubt I had is that the biasing resistors are so close to each other. How and where do I connect the multimeter probes to the resistor?

I you (or anybody else) can help, that will be highly appreciated. Sorry for hijacking this post.