Bogner Shiva 20th ( What KT88's? )

I put the Ruby KT88's in my 20th Anniversary and I had to change the bias resistor....

It would only bias up to 24mA when the variable resistor was turned all the way up.

Awesome tubes though!
 
KT88s - Sovtek, JJ, and thetubestore.com "Preferred Series".

6550s are usable too - EHX has a good plate handling capacity.
 
When I had mine the EH Kt88s and Sovteks sounded best to me. The JJ's were ok at lower volumes but tend to compress and add too much low end to an amp that is already thick as a fresh milkshake! Honestly Rheinhold knows what he is doing and the stock tubes imho sounded best in that amp. I did have to swap bias resistors when I got a new set, the range is fairly small on the dial.
 
Just recently got a chance to compare the 3 pairs I have. These were in a mini-Major homebrew amp so it is an Ultralinear power section. 500vdc plates and biased at about 56mA cathode current per tube.

Gold Lion - The most balanced tone of the 3 with the sweetest top end. It had the least amount of low end but not by much, also the least amount of glassy/shimmery highs but again, the most balanced.

JJ - Big, round low end with a bit of extra sizzle on top. This is similar to my experience with JJ 6L6s relative to other 6L6s.

Penta KT88SC - Muscular bottom end and lots of top end detail but missing some of the important mids guitar players need. Might be good for bass or HiFi but based on this pair, not the best choice for a guitar amp.

Relative to the Gold Lions, the JJs sound a little bloated in the lows and sizzling in the top while the Penta sounded scooped (and not in a good way) and really glassy.
 
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