This is my attempt at emulating the valvecaster using transistors, I haven’t got round to building a valvecaster yet, so this is mainly based on the results from somebody else valvecaster build. it’s basically the last two stages from a big muff. The first of the two stages is a clipping stage, but unlike the big muff, this gain stage has got variable gain, the 470KB pot adjusts the gain and bias of the transistor, the 22k in series with it, sets the minimum possible gain, and to make sure there can’t be 0 ohms here.
The diodes in the first stage are different from a big muff. instead of a single pair of silicon diodes. I have used 2 silicon diodes in series with each other to hardclip one side of the waveform, and used 2 mosfet transistors acting as diodes to soft clip the other half of the wave form. the reason why i used 2 in series with each other was to increase the threshold point before clipping. this increases the dynamics, and allows for softer playing to be less distorted.
the last stage is just a clean boost, but as both stages invert the signal this ensures that the output maintains the same polarity as the input. 6x silicon didoes were used at the output to clip the signal roughly around 3 volts, and to produce symmetrical hard-clipping. this has been built but not fully tested yet.