Tube Amp Archive

If you want increased gain, more volume, and earlier breakup with the push-pull designs, the easiest modification is to employ a 12AX7 paraphase inverter in place of a 12AU7 paraphase inverter. The figure below shows the component values that I use for a 12AX7 paraphase inverter. They were taken dir...

My apologies everyone. I found another error in one of the value tables. The schematic and corrected component values table for the push-pull 7591A amp are attached. The values of R23 and R24 were wrong in the original posting. The correct values are 2.2K/3W and 10K/2W, respectively.

I realize that I stated the wrong value for R15 in the single-ended 6V6GT amp variant described in my previous post. R15 should be 10K/2W rather than 2.2K/3W. The schematic and corrected component value table are attached.

I have been interested for some time in designing low-wattage amplifiers that have a rich tone that remains clean through most of the amp’s volume range. After a great deal of tinkering and a bit of good fortune, I found that using a low-gain tube such as a 12AU7 in cascode configuration for the fir...