siore

Thanks Myles. That sounds like good advice.

Following the schematic, it takes the same voltage to the heaters and plate. You're right in that it has a low plate voltage. No step up tansformers or anything in the circuit. So if I plug a 9v adapter, it takes 9v to heaters and 9v to plate. That is the designed voltage for the pedal, and some guys say they run it at 12-18v with 'better' results. But I'm a bit concerned about tube life. Is it asking a lot out of the tube for it to see 18v at the heaters? Am I just burning them out faster that way? Reason I ask is that I have both a 9v and 18v power adapter.

Myles, is it safe to run a 12au7's heaters at 18v? The GE spec sheet says 12v, but I'm wondering if the tube has a tolerance for higher heater voltages. It's for a valvecaster (starved plate design boost pedal). Thanks.

Myles, on another note, you said in your primer document that shuguang tubes are promising (my impression at least). I see a lot of them on ebay, but it appears they aren't matched sets. How would I go about matching them using the bias balance pot on my amp? I'm thinking I should still measure idle dissipation (plate voltage and cathode current), and swing the balance so they're about roughly matched. How would you proceed to use the bias balance the way cbs fender intended for it to be used?

Much thanks! Found some answers on page 6 as well.

Hi myles! Came to this board from your amp blueprinting page. I've read through your amp blueprinting document countless times as well! What I have is a '74 dual showman reverb, which doesn't have a bias adjust trimmer pot, and I intend to keep that way. Suppose I want output tubes to have a long life, and yet still run hot enough to sound good, I'd want tubes equivalent to a gt rating of 4-7 right? What do I specify to Steve Martin, since I'll be ordering some from AES? My fear is that after getting a nice matched quad winged c sed 6L6GCs, it will run cold and have some crossover distortion (or low ghost notes, or just sound really sterile), or on the other (worse) end of things, red-plate from the get-go! Hope to hear from you. In the meantime, I'll go through the 160 pages of thread here. Just ignore this post if it has been answered and I'll eventually stumble onto it here. Thanks.