Re-tubing a McIntosh power amp

The Tube Store is where I go!

GL KT88s are about 210-230.00 per quad. I'd stick with KT88s not 6550, and yes there is BIG difference.

GL are a good sounding valve for one. A 6550 in the older 1961-67 275s that's a different story. The amp is made differently. Actually I like a GE6550 better than even the old GLs. BOTH are wonderful valves though..

PSVANE is just a no no too. I tried a few times.. The signal valves not too bad, but the power valves.. YIKES!

I know I have used some Solvex that were REALLY good. The problem I had was the failure rate out of the box and for about the first 50 hours or so.. SUPER high.. I bought in bulk, and didn't lose my shirt, BUT I was burning in quads for a while.. 15% failure rate, THEN they were fine..

Over 30 valves out of 200, three different times.. Some put on quite the fireworks display in a tube.. Scare the heck out of you the first few times.. :-)

OP rolling valves is swapping, but normally we roll small valves for the final tweak. Some have fewer to roll than others.. That's all.  LOL

Thing is tho, by your intent you will in fact be tube rolling!
Are you looking to replace a whole set of signal and OPT’s or a combination of same?
If you are considering replacing valves ( Mainly the KT’s) that you feel.  may be a little tired my first inclination would be Mac factory tested and approved via a Mac dealer.

 

not rolling but upgraded from stock, oh baby what a quest.

stock tubes from whom, OEM tubes or you bought used? I imagine OEM's put what they believe is best, then people replace/roll. The difference to the OEM of 'stock' tube cost is insignificant to the cost of the amp.

You will get into the issue of Bias, I started a thread about that 1-1/2 yrs ago, after ton's of advice, then Covid, all kinda other new stuff all over the house, did nothing about bias.

https://forum.audiogon.com/discussions/tube-bias-socket-to-me?highlight=bias%2Bsocket%2Bto%2Bme

Since 1973 I have messed with these power tubes: EL37's; EL34's, 6L6; 7581, 5881; 6550, KT88. weak, shorts, got hold of some money, .... a variety of amps and reasons.

Most recent, my Cayin A88T came with used 6550's. I like having spares, got some b'day $, bought some new KT88's. I loved the 6550's, I love the KT88's more. Convinced myself with my own expectation bias?

Source: Brent Jesse, http://www.audiotubes.com/

It currently has the standard McIntosh branded tubes in it. I have just read that they have a pretty high failure rate and there are much better tubes out there for that amp. I want to replace with the same types of tubes (KT 88, 12 AX7A, etc) but switch to a different brand.