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KT88 Tubes

I am new to tube amps having acquired a Harmon Kardon Citation II about a year ago. A little while ago I started experiencing one of the channels dropping out and an occasional loud pop. Today I noticed one of the KT88 tubes glowing purple where the rest glow orange so I have assumed that the tube has gone bad. As I bought this amp used, I have no idea of the age of the tubes. So I have a couple of questions. First, should I replace just the two tubes on the bad channel with a matched pair, or should I replace all 4 tubes with all 4 being matched. Second, any recommendations for good quality KT88 tubes? Any other thoughts or ideas would be appreciated. 

russbargmann
russbargmann OP
1 posts
 

Everyone, thank you for all the helpful suggestions. Over the net several days I will be trying them out.

searchingforthesound's avatar
searchingforthesound
41 posts
 

Old thread but replace all four at once matched set..  I use PSVane and vary happy

 

Amazon.com: New Current Matched Quad (4) Psvane KT88-T Classic MKII II Series Vacuum Tubes : Musical Instruments

Gold Lions prob good as well

danmar123's avatar
danmar123
486 posts
 

KR KT-88s & my Prima Luna HP, I couldn't be happier.

dogearedaudio's avatar
dogearedaudio
190 posts
 

@guscreek 

Yes, that's a risk, but often you can catch red-plating tube before it's damaged.  At least then you know not to keep trying new tubes until you can get the amp serviced.

 

westcoastaudiophile
497 posts
 

@russbargmann unless your tubes ran more than 5000+ hours, you may swap L <=> R ones, and bias / balance accordingly to service (schematics) recommendation. 

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