KT88's in a MkII?

I'm obviously the new guy here so here goes, I recently purchased a pair of rewired MkII's on ebay. The driver boards are stenciled Jkk Mk3/6, there are 2ea. Sovtek 6922 tubes on each board, the rectifier tubes are Mullard (ServiceMaster) 5U4GB's. The power tubes are Chinese KT88's, and there is a sticker on each amp that says: BIAS .42V, both amps sound fine to me through my JBL L-65's. I also got 4ea, 6550's with the amps, my question is which pair of tube should I be using?

Any information would be greatly appreciated. Terry

Bob,

Thanks for the information, I've read that replacing the 50ohm 10watt resister with the C354 choke is also a smart move, I'm also considering replacing the 5U4's with the GZ34, your thoughts on this?

Thanks,

Terry

Bob,

Now I'm concerned....I removed the bottom covers from both mono blocks, it turns out instead of the standard 50ohm 10w resister there is a pair of 300ohm 10w resisters in parallel for a value of 150ohms. The quad cap was replaced by several smaller caps siliconed to the inside of the chassis. Both amps play fine as far as I can tell and hear, the local Radio Shack has the 50ohm 10w wire wound resister for $2.99 a pair. Should I replace or let it slide until I replace them with the C-534 chokes?

I have pics of the underside of both amps if you wish to see.

Thanks, Terry

Bob Latino wrote:.....my ears tell me that 6550 tubes are a little more "tubey" sounding than KT88's with more mid-bass content.

Just to clarify....

does your statement mean that 6550s sound more tubey and have more mid-bass?
or that the 6550s sound more tubey and the KT88s have more mid bass?

Thanks

Thanks

Bob,

Can you tell me what diode is normally used to replace the 20ma selenium rectifier in the MkII?

Thanks,

Terry