I tried to build a Express on a Traynor chassis using the Traynor PT and OPT. OPT is 5.2K and the PT is 325-0-325. Voltages were 50 over and as a result the amp is stiff and sterile, too much fizz on the top end. As an experiment I hooked the amp up to a variac and lowered the voltage to experiment and at 100vac the amp sounded very good. Lots of crunch, not stiff sounding and didn't fizz out.
I took measurement of voltages and now have 370 on the plates of the EL34's instead of 450 and preamp voltages are bang on. If my math is correct would I substitute a 265-0-265 PT. Only other concern I have is how the lower heater voltage affects tone ect. as I lowered all voltages with the variac and am curious what effect the new PT will have with proper heater voltages. At 100vac the heaters were at 5.4.
Thoughts?
Voltage Question
Moderators: pompeiisneaks, Colossal
Re: Voltage Question
You could always put a big zener diode that bolts to the chassis on the B+ CT. Did this on a marshall style build. Not sure how to make the calculation to get you where you want to be though.
It's all about the tone!
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Reeltarded
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Re: Voltage Question
Stay with the variac on that amp. Easy choice for me!
You are pretty much on target if you want to do the swap though.
You are pretty much on target if you want to do the swap though.
Signatures have a 255 character limit that I could abuse, but I am not Cecil B. DeMille.
Re: Voltage Question
I thought about staying with the variac but it drops the heater voltages thus impacting tube life. I think I'm going to swap the PT and then fine tune. What difference will 300ma PT be over a 200ma. I'm assuming 300 will put my voltages a little higher?