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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
jburidan
672 posts
 
http://www.jacmusic.com/KT88/kt88.htm

Lots of info at jacmusic.
dentdog's avatar
dentdog
300 posts
 
My experience is that the vintage NOS tubes are considerably more reliable.
As for Ebay while I have bought successfully there, when it comes to high dollar output tubes I am hesitant. 
I wil say that the tubes you use in these amps can make a big difference.
Input and driver tubes can influence things greatly. Siemens-Halske 12AT7s are quite nice. RCA 12AX7s seem to round things out. Good bass. Andy at Vintage Tubes provided my AX7s. 

angelgz2 OP
37 posts
 
@dentdog thats true. I didn’t like the EAT tubes at all as they sounded muddy and lacked bass, despite being priced at $450 each. Popped my RCA 6550s and unit came back to life lol. I’ll see if I can track down a quad of black plates 
richopp
88 posts
 
Try Tube Depot and see what they have.

https://www.tubedepot.com/
thomasgc
8 posts
 
you probably got a bad tube. I would contact your seller for a replacement I have been running Golden Lion reissue and Shuguang 50 year treasures in my Mcintosh 275 vi for about 5 years with no issues whatsoever 
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