2. amps-preamps
  3. 180145-2094

KT88 for McIntosh MC275 mk.IV?

I've had Psvane black bottles for 11 years and liked them. At the time they were a clear improvement over stock tubes. I purchased 5 and rolled them quarterly, anticipating one will eventually fail, which happened. A second one has now failed so I need new tubes. These were probably used up already anyway.

The amp is currently used for midrange (300 to 1200Hz) amplification in an active system, so the frequency extremes aren't most important.

I'm looking at Genalex Gold Lion and Psvane. Any experiences that can help me decide?

I could buy 5 Gold Lions and spend $500, or buy 4 Psvanes for $500 and use the remainibg 2013 Psvanes as back up in case of failure.

Thank you!

lewinskih01
lewinskih01 OP
909 posts
 

I went ahead and purchased 2 matched pairs of Gold Lion KT88.

Pair A has a tube rated 37 IP/4600 GM and another rated 38 IP/4700 GM.

Pair B has a tube rated 37 IP/4400 GM and another rated 36 IP/4500 GM.

 

Should I install A1 in V8, A2 in V9 and B1 in V10, B2 in V11, or a different order?

Thank you.

russ69's avatar
russ69
3,519 posts
 

I think that amp is auto bias? Does it auto bias each tube, a pair of tubes, or the whole lot? If it's the whole lot, they can go anywhere and you should have bought a matched quad. If it auto biases two tubes put the matched pairs in each paired bias location. Single bias a matched pair still go into the same amp channel. 

lewinskih01 OP
909 posts
 

It does auto bias. However I don't know if it does it for each tube, pair or whole lot.

Maybe someone with MC275 mk.IV can tell. A quick search brought Ron-C (a McIntosh technical employee then) circa 2005 at Audiokharma McIntosh forum making comments about auto-bias, but no clarification about single/pair/whole lot.

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