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previous: Jim Salman For typical fixed bias class AB Fen... -- 5/30/1997 4:30 PM View Thread

Re: 6L6 bias adj.

5/31/1997 7:27 PM
M/J
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Re: 6L6 bias adj.
I bought a book by Torres. I found it to be good reading. He had a scale on plate voltages and the correlation between those voltages and the ma of current drawn at the cathode. My schematic called for 425v at the plates but when I measured the voltage it came up 415. Maybe one of you can explain the voltage being out of spec. Anyway Torres called for 28.8 to 34.3 low to high AB class respectively. In the book he recommended that you bias to the cooler spec for rock music and towards the higher end for cleaner tones. I biased at 28.8 and the amp sounds great. I went from the low range to the high range and could not detect much of a difference in the sound. I should also say that my hearing is not the best. The amp runs cooler at the lower setting and breaks over good when cranked up. Jim...you state at the bottom of your thread that the 6L6 and the 5881 put out different watts. Is there any difference in the tone? If so... what? I'm running a matched set of RCA black plate 6L6's in it right now with Telefunken preamp tubes. I did change the Driver tube from a 12at7 to a 12az7 RCA and the second stage preamp from a 12ax7 to a 12ay7 GE. The telefunken seems to push that GE real good and the RCA az driver is not as brittle as the AT. It makes the amp have a warm overdriven sound. I appreciate all the help you guys have been giving me. I'm really having fun messing with this thing. I also want to thank you guys for showing me that the guitar and effects are only half of the equation. M/J

 
Replies:
Jim Salman Although my personal preference is ... -- 6/2/1997 12:26 AM
Dave Charneski I've had the same experience with t... -- 6/2/1997 12:02 AM