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KT88 vs 6550 tubes

I recently got a quad of EAT kt88 tubes for my Mcintosh MC275. Those are supposedly revered as one of the best. However, less than 10 hours one of them had a spark of fireworks in it and shorted the fuse. I heard KT88s are in general not as reliable as 6550. Is this true? 

I thought also that KT88 and 6550 are interchangeable in the MC275 without any additional bias adjustment. The original 6550 tubes in it has been working for a long time without issue.
angelgz2

Showing 1 response by schubert

schubert
4,867 posts
 
I’ve had similar problems . The best buy , unless you want to spend 2K $ on NOS (which may not be same) Sylvania 6550’s is to to buy a matched quad from "the tubestore.com " This Canadian firm is honest
and does a good job .I got a Quad of KT 88 from them few months back to replace 6550’s only to see the sound difference . In My AES-25 Super Amp the 88’s are a bit clearer which I like .

The 6550’s ran for 4 years and are still fine . tubestore calls these quads "Preferred" , only few bucks more .
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