New Tubes- Need Burn-In?

Well, after much experimentation and help from all you guys I believe I have whipped the Cayin into line. Damn it's sounding good now!

My take on the amp:

The stock tubes are marginal at best- which is surprising considering the glowing reviews the amp has received.

The EH KT-88's I bought to try are too "edgy" in that amp- detail is good but everything has a noticeable level of attack.

I now have a quad of Svetlana "Winged C" KT-88's from Upscale Audio that were thoroughy tested and matched. I also replaced the Chinese 6SN7's with 2 NOS Sylvania 6SN7W's.

Man- it's like night and day- an altogether different amp. Great transparency, liquid vocals, in the room realism with good material, and better bass than I had with either the Cary SLI-80 Signature or the Manley Shrimp/Conrad Johnson MV-60 combo.

My final touch comes next week when I receive my NOS RCA Red Base 6SL7's to replace the 2 remaining Chinese driver tubes.

I'll report back after that move!

Dan I have plans to get the A88, months off though. What did you pay for the Svet quads? And the 2 sets of pres? Why did you use 2 different types of pres? Different #'s?
I may replace the tubes in my Cayin cdp if that will make a difference.. Any help appreciated.

Bartokfan-

I paid $170.00 for the Quad of Svetlana Winged C KT-88's from Kevin Deal at Upscale Audio. Yeah, I could have bought them cheaper, but I wanted a thouroughly tested and matched Quad.

The Sylvania 6SN7W's replaced the two Chinese 6SN7's that came in the Cayin. The Cayin also employs 2 6SL7's, which is where I'll stick the RCA Red-Base when they arrive next week.

The Sylvania's were about $110.00 for the pair. The RCA's were $150.00 for the pair. Expensive, yes, but with a 10,000 hour lifespan they're worth it in my opinion.

The Cayin A-88T is WAY sensitive to power cords...if you buy one experiment and find what works best in your rig.

Also remember this amp is NOT self-biasing, regardless of the false info in some publications. Biasing it is easy, but you must remove the bottom cover and stand the amp on it's side to do so. Pain in the ass? Yep, but the amp is worth the trouble.

I have a similar take to yours on the EH vs. SED versions of the KT88 as for how they sound, but a diametrically opposed opinion on which I prefer. I enjoy the clarity and speed of the EH, and didn't really care for the warmer SED (I prefer their 6550C more in my VTLs as a viable compromise, and admire their EL34 too).

I'd also found the Chinese 'Ruby' 6SN7 to be a very competent driver in a CJ amp, close to the same ballpark as some NOS American versions (something I couldn't say about the Sovtek). But of course we all have different systems and tastes, glad you've identified something for yours.

I've generally found that power tubes take a couple days' worth of *playing time* to open up and flow, which for most people means a week or two. And whenever I've had incipient problems with glare, it's always turned out to be traceable to microphony of the input tubes; other than trying to get the best-sounding and least-microphonic NOS examples you can, I would also recommend trying some type of tube dampers here to help tame glare.

Once you get all that squared away and if you still have them hanging around, you may want to revisit the KT88EH's after a while, let them finish burning-in and see what you think again. They will always sound leaner and less 'tubey' in comparison with the SEDs (to me they're more neutral), but I feel they hold a few other advantages in fidelity, provided the tonal balance can work with the rest of your system. (BTW, if you -- or anybody -- is in the market for a spare matched-pair of little-used SED KT88's, email me.)

Zaikesman- All good points. I noticed that the EH KT-88's had improved significantly as I used them. I am hanging onto them for precisely the reasons you mentioned.

Thanks for making me think!