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Re: Big question!

1/15/2006 4:54 PM
Steve Dallman
Re: Big question!
If I remember right, I ended up using larger resistors than I started with. Around the time I did my DR, I got in a UL Twin Reverb for repair. It belonged to a local blues player's son who played in a metal band. He was murder on tubes and speakers.  
That amp was cold, cold, cold. I took two of the 4 tubes off the UL taps, and it helped slightly. Finally, I switched to cathode bias, and put in a post PI master (replacing the pull-boost, pre-PI master). The first set of tubes died a quick death due to screen failures (Sovtek 6L6WXT+) but a change to 1k/5W screen resistors, new tubes (Ruby at the time only because they were on sale) and it was good to go.  
I recently got that amp back as the speakers died again, but was happy to find the amp sounding great and still running without tube failures. His original speakers finally died. I had repaired long suspension tears up the first time I had the amp. This time I put in a pair of Jensen C12K's and was very happy with the result.  
Back to your post...I haven't heard much difference in cathode bias caps either. I probably used 50uF. I'll get back to you.  
Again, I switched to 6L6's this time because the power transformer I had was too high voltage for 6V6's and I've been too pleased with the sound of the cathode biased 6L6's to change back. We have other 6V6 amps here at home if I need that vibe.

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