A low-power desktop size guitar amp head driving any 4-16ohm speaker? Here we go. I combined some layouts and modified them a little. This amp has two main parts; Runoffgroove’s Tonemender as a preamp, and Ruby Amp as a power amp.:
Tonemender side’s layout is taken from tagboardeffects, with slight modification. there was originally a A500k potentiometer in a place of that 22k resistor. I didn’t want two volume pots, so I replaced it with a resistor. Got an advice that 15-22K would be near the unity gain, and first tried 15K. It boosted a little, so I replaced it with 22K. I also used NE5532 instead of TLC2272 as mentioned in the original layout. Otherwise my build is as described above.
Ruby Amp side’s layout appeared to be too large, so I needed to diminish it drastically. I also replaced MPF102 with 2N5457 because I didn’t have any MPF’s in hand . In the layout above it’s not modified yet, but I managed to shrink it to 7×16 slots. Now it fits nicely to 1590B. It’s pretty nice to have this in my desktop in very next of my layout testing box. And as this works with regular 9V battery, you can take this and connect it to practically any speaker you can find. Pretty fond companion in a road trip. When cranked this goes to subtle overdrive. The main features are as follows:
- NE5532 in a preamp, LM386 in a power stage
- 0,5W /4-16ohm
- Bass, treble and mid control with a mid shift switch.
- Volume and gain
- Works with 9V negative tip power source or 9V battery.
- 1/4″ jack input and speaker output.
The maximum current draw is questionable. It think it’s around 150-200mA when cranked. That would give some 3-4 hours of working time with a single battery. Amp cranked with guitar volume turned down takes approx. 40mA. LM386 should work even with 5V, and I tried this with old battery with 5,9V of voltage left. Worked all right.