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Vintage threads from the first ten years
| previous: Stephen Delft I saw in Steve A's recent reply, a ... -- 1/2/1998 11:17 PM |  |
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Re: what is Pro/SuperTexan
 1/3/1998 4:25 AM |
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Steve Ahola | Re: what is Pro/SuperTexan Stephen: My "Pro/Super Texan" is an old butchered-up '65 Pro Reverb amp which I resurrected by putting in the Dan Torres SuperTexan point-to-point circuit board. The transformers, choke, and power supply filter caps are all original (hence the B+ of 473vdc), but practically everything else is new, and of the Torres ST design (basically a tweaked Fender, with an added gain stage in the OD channel ala Mesa Boogie). His book on tube amps recommended a bias current of around 25mA (per 6L6GC tube) for a B+ of 473vdc. Most of the posts here at AMPAGE recommend a bias current of at least 31mA for Class AB, but I think they may have a lower B+. I tried out bias currents between 31 and 35mA for 3 matched pairs of output tubes, and found the best values for my ears to be around 28.5mA for fixed bias and 29.7mA for cathode bias. The formulas in Dan's book for determining the cathode bias resistor didn't work right, so I just experimented with 3 or 4 different values and ended up using 2 resistors adding up to 775 ohms. The only complaint I've heard about cathode bias is that it has a lower volume than fixed bias; I got around that by setting the fixed bias pot to produce a bias current approximately 1.2 mA lower than in the cathode bias mode. Steve Ahola |
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| stephen Steve, |