How can I improve the bass response in my SET vacuum tube amplifier? Answered
I'm experiencing an odd problem with my new SET amplifier. I just built Fred Nachbaur's MiniBlok 13EM7 SET amplifier and the bass response is poor with the power turned on, but when I turn off the plate supply and allow the amplifier to run on the energy stored in the capacitors, there is an immediate and very audible change in the rendering of the lower frequencies. I followed the schematic as closely as I could, but until my Edcor 10k:8 Ohm Output Transformer arrives, I am using a small 2K:8 Ohm Output Transformer from an old transistor amplifier. I have tried to install a filter choke and another capacitor in the power supply, but this did not improve the audio quality. Does anyone have any advice? Is the output transformer the problem, and if so, why?