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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

Showing 1 response by gbro

gbro
3 posts
 

I have been a long time fan of KT88s for sheer punch in the bottom and above average reproduction of the rest of the frequency range. I have a few different amps and my main amps ( Cary audio 211 Founders Edition) do not use KT88s but I still have an Audio Research integrated that uses the KT88s. It is a great backup unit and I have been using the Sophia Electronics Blue Bottle KT 88s. They are a wonderful tube and you can get a quad matched in a C, B or A grade. I have always gone with the A grade even though they are a bit more expensive I have never been disappointed by them at all.

https://sophiaelectric.com/collections/vacuum-tubes/products/pages-se-kt88

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