Midway Fair | 1 decade ago
The Snow Day OD is a FET- and MOSFET-based amp simulation overdrive running on 18V that includes a switchable miniature compressor circuit and soft clipping in a "power tube" section. It goes from glassy "mostly" clean to either open or slightly compressed edge of breakup that feels very similar to one of my favorite amps, up to a medium gain compressed sound. It has lots of harmonics without sounding overly clipped, and a very wide dynamic range.
It uses some principles from several Runoff Groove circuits, Aquataur's mini compression circuit from his mods to the Umble, and Mark Hammer's Stupidly Wonderful Tone Control (which rolls off treble without changing the volume).
Although it's not directly based on any amp in particular and I wasn't going for a particular sound, I did have a couple amps in mind (both Deluxes -- a friend's 5E3 clone and a 1949 Deluxe at Invisible Sound Studios in Baltimore) while I was designing, aiming for a similar feel and gain level to them if not necessarily their tonality.
A FET-based preamp stage includes a miniature compressor and is followed by a tone control that precedes a "power tube" stage, with MOSFETs used as clipping diodes in a feedback loop of a MOSFET amplifier, with the clipping softened a little.
The gain goes from very clean at 9:00 to a very good edge of breakup sound at noon, to medium gain territory as you go higher.
The tone control rolls off treble starting at 15KHz down to 685Hz. It can get a little brighter and a little darker than the bypassed signal.
The pedal runs on 18V internally for a lot of drive but also a lot of headroom, making for plenty of volume dynamics even with the clipping.
I've also posted an audio-only demo on my website, recorded straight into a recording interface with no EQ or effects. It will be easier to hear the compression circuit's subtle effect in that recording, and I've also done some samples with overdubbing and in combination with an overdrive and a boost.
