owlexifry
Well-known member
after breadboarding an MT-2 and doing some deep dives i become aware that the pedalpcb shop has a board for a pedal that Randall released a while ago, called the RRED pedal.
it’s pretty much a bang on clone of the Randall RG100 red channel, except with the ‘saturation’ switch mode hardwired on (4148 hard clipper pair), and the presence control hardwired to halfway.
before building this pedal i breadboarded the circuit to investigate the modes, different JFETs, and whether a presence control might be good.
ime the ‘saturation’ mode is much less desirable, cuts the volume considerably, and just sounds worse compared to the ‘sat’ off mode, which per the RG100 schematic, is an opposing series pair of 4V1 zener diodes to ground.
i decided to leave the 4148 clippers out, and leave it with 3V9 zeners. (couldn’t really be bothered finding 4V zeners, if they exist, 3V9 is close enough for me).
during breadboarding, i carefully selected x4 2N5484 JFETs with the best specs out of a lot of x10, tried those and then noticed 2N5457 have pretty close spec ranges, so i picked out some of those in a good spec range and found they sounded slightly better than the specified 2N5484s. so i built it 2N5457s instead. i also used 100K trimpots, seemed to bias for a better tone/drive than 50K trimpots.
i noticed the power supply sagged less than 24V under full load with 1N4007s for the chargepump (per schematic), so i tried dropping in 5817s to boost it up a little.
unfortunately i made decisions to go ahead and solder in 5817s before i realized that x3 35v 220uF caps were not going to fit well. whoops.
so i managed to squeeze in a 35v cap for the ‘first’ 220uF filter cap, which was sitting at just over 25.0v, and 25v caps for the last x2 220uF, which were seeing about 24.4v. hasn’t had any issues so far
result:
after all the JFET and opamp distortions i’ve tried, this might actually be one that i find doesn’t immediately feel lacking compared to a good tube amp lead channel, and perhaps offers something different and cool that many tube amp lead channels can’t do.
cos this thing can get pretty brutal and has tonnes of overdrive/gain, but still has a huge dynamic range and heaps of low end.
here’s a demo with a Boss MT-2 (Kirk Windstein/Crowbar attempt) & SD-1 for boosting.
it’s pretty much a bang on clone of the Randall RG100 red channel, except with the ‘saturation’ switch mode hardwired on (4148 hard clipper pair), and the presence control hardwired to halfway.
before building this pedal i breadboarded the circuit to investigate the modes, different JFETs, and whether a presence control might be good.
ime the ‘saturation’ mode is much less desirable, cuts the volume considerably, and just sounds worse compared to the ‘sat’ off mode, which per the RG100 schematic, is an opposing series pair of 4V1 zener diodes to ground.
i decided to leave the 4148 clippers out, and leave it with 3V9 zeners. (couldn’t really be bothered finding 4V zeners, if they exist, 3V9 is close enough for me).
during breadboarding, i carefully selected x4 2N5484 JFETs with the best specs out of a lot of x10, tried those and then noticed 2N5457 have pretty close spec ranges, so i picked out some of those in a good spec range and found they sounded slightly better than the specified 2N5484s. so i built it 2N5457s instead. i also used 100K trimpots, seemed to bias for a better tone/drive than 50K trimpots.
i noticed the power supply sagged less than 24V under full load with 1N4007s for the chargepump (per schematic), so i tried dropping in 5817s to boost it up a little.
unfortunately i made decisions to go ahead and solder in 5817s before i realized that x3 35v 220uF caps were not going to fit well. whoops.
so i managed to squeeze in a 35v cap for the ‘first’ 220uF filter cap, which was sitting at just over 25.0v, and 25v caps for the last x2 220uF, which were seeing about 24.4v. hasn’t had any issues so far
result:
after all the JFET and opamp distortions i’ve tried, this might actually be one that i find doesn’t immediately feel lacking compared to a good tube amp lead channel, and perhaps offers something different and cool that many tube amp lead channels can’t do.
cos this thing can get pretty brutal and has tonnes of overdrive/gain, but still has a huge dynamic range and heaps of low end.
here’s a demo with a Boss MT-2 (Kirk Windstein/Crowbar attempt) & SD-1 for boosting.
