Has anyone here been tinkering with the VOX AC30C2 amps? After a good while of owning one, it's turn under the soldering iron came up... So here's the schematics with a few notes on them. All mods are in red to easily identify the changes (and leave the schematic useful for troubleshooting a perfectly normal amp too). The goals were not to change the character of the amp much at all, but lightly change the way it breaks up. And to shove the noise floor as low as practicable. As to why: In my experience, the higher the note on the guitar, the lower the peak to peak electrical signal. Not only does that make the highs effectively quieter, but also distort less or even fail to reach distortion. The AC30 has small coupling capacitors between stages and so bins off a lot of bass - which sorts out the volume difference, especially so in the top boost channel. However, a small coupling capacitor has high impedance at low frequencies. So it doesn't load the valve driving it much. Thus the valve doing the driving sees a slightly higher impedance at low frequencies and has a little bit more gain there than at the highs than it would do if the coupling cap was much larger - by a little less than 1dB (small but still a thing). The character of the amp would change massively if the coupling caps were made much larger - so another method of lowering the driving valves gain was required. This is accomplished by using a much smaller cathode bypass cap. This reduces the gain of the valve around the lows by about 5dB and leave the highs at full gain. A damped capacitor smooths the response between the 2 bands, creating a slow rise in gain from 100Hz to 1000Hz of about 4dB. And then a slightly larger coupling cap to the next stage is used to get back some of the lost bass. So, in short, this transforms the amp from a bass boost followed by a high pass filter into a true top boost amp. For the clean channel, this happens once and for the top boost channel, twice. The net effect is similar sounding clean tones followed by more even breakup across the frequency range as its driven. For me that makes it more tactile. Also, by decreasing low frequency gain, mains hum is not amplified as much, which reduces noise there. Other more simple mods are: Putting damping resistors in series with the treble caps on the volume pots. This makes it sound a little less bright and more uniform across the volume range Increasing the amount of bass that can go through the FFX loop - which is where I run reverb pedals Installing power rail bypass caps on a couple of op-amps - because why not Increasing the size of the caps buffering the HT for the valves - which reduces noise by lowering the roll off frequency of the filter made by them and the resistors separating the B+ rails The net result is quite nice and tactile with a very low noise floor - easy to forget its turned on... And finally - it's all fully reversible.