[ctviggen]

I have a Cayin 860 amp that has the following tubes:

4 6550EH tubes in the main amp section
12AX7, 12AU7, and 6N6 in the preamp section

Does anyone have recommendations on which tubes (if any) I can change, and suitable replacements for these tubes?

Thank you!

[Balle Clorin]

5751 for the 12AX7 give lower gain and less noise form preamp it that is a problem.
12AU7 i have replaced with 5814.
I got some russian 6N6 (6H6N) from ebay.

You may try KT88 for the 6550. I run New Re-issue  tungsol 6550

http://www.tubedepot.com/5751.html

Best regards Balle

[kenreau]

I had the Cayin 860's for a couple of years.  I made a ton of upgrades to the caps, resistors, wires, parts, etc.  They are exceptional amps for the money with the right speakers.  You can do a search here to read more on my upgrades if interested.

I used NOS Mullard Blackburn tubes at the 12AX and 12AU locations, RCA Cleartops at 6H6N and the new/reissued Mullards octet matched set for the EL34s.  The upgraded tubes made a nice improvement.