Rock Dove (A Rat-Inspired Overdrive)

[Aleph Null]

This doesn't sound like the Rat distortion; while it's capable of a fair amount of gain, it's generally less aggressive—and in my opinion more versatile. That said, if you squint at the schematic, it looks a lot like a Rat. What is a pigeon but a rat with wings?



Wiring vero builds is always an undertaking. I tried to keep wires neat while leaving enough length for troubleshooting if needed.



Like the Rat that inspired it, a non-inverting opamp feeds clipping diodes to ground. The high pass filter is less aggressive, starting at 148Hz. There's also a 6dB high shelf at 1.4kHz to add a little sparkle when it starts to saturate. Clipping options include, opamp, LED, and germanium diode. The tilt EQ has a broad mid bump between 480Hz and 1kHz. The "Flat" control bypasses the EQ and increases the output a little. The transistor buffer keeps the volume control from effecting the tone. I used a BJT instead of a JFET because they're easier to source and work just as well in this application.



It goes from clean in some settings to proper distortion in others. It's strength is overdrive. The EQ and voicing is mid focused, but not as extreme as the Rat (or even a Tube Screamer). Were I to build a version 2, I'd probably use a dual opamp chip and use the second stage to buffer output instead of a BJT. I don't expect there would be an audible difference, but the layout might be a little more compact.

[benny_profane]

Nice work! The wiring definitely looks like thought and planning went into it.

This may be one for the breadboard. I really like the Rat, but I think your characterization is correct. So, rather than sweeping the entirety of the gain gamut, this stops short of fuzz territory and gives more nuance within the distortion range? Interesting work with the EQ. Do you find this active shelving filter more useful than the more extreme shaping of the Rat's gain stage HPFs?

[diablochris6]

I have a DIY Rat around, but I don't play it very often because of the aforementioned harshness it can get. This seems like a pretty good alternative. I wonder if it would warrant trying other tone options like the stupid easy tone control or even a gyrator based EQ. Either way, great thought process, and great execution.

[leftwing73]

Beautiful - classy look and a very clean build.

[Aleph Null]

Nice work! The wiring definitely looks like thought and planning went into it.

This may be one for the breadboard. I really like the Rat, but I think your characterization is correct. So, rather than sweeping the entirety of the gain gamut, this stops short of fuzz territory and gives more nuance within the distortion range? Interesting work with the EQ. Do you find this active shelving filter more useful than the more extreme shaping of the Rat's gain stage HPFs?

Thanks! I tried to lay out the vero to make the wire runs as short as possible.

The Rat is capable of 67dB. The Rock Dove does about 48dB. Also, the clipping threshold will be higher in the opamp and LED modes, so it's definitely geared more towards overdrive than distortion. That said, if you put it in germanium mode and dime the gain, it gets kinda fuzzy.

Standard Rat pre-clipping EQ is much more dramatic for sure. I think the huge peak around 1.5kHz is a big part of the rat sound. Those mid frequencies are saturating more and sooner than everything else. By comparison, the Rock Dove has more bass and treble going into the clipping section. The high shelf adds articulation and sizzle without the same aggressive poke of the Rat. The Rock Dove is still mid-rangey because of the tilt EQ, but sounds full frequency compared to the Rat.

[Aleph Null]

I have a DIY Rat around, but I don't play it very often because of the aforementioned harshness it can get. This seems like a pretty good alternative. I wonder if it would warrant trying other tone options like the stupid easy tone control or even a gyrator based EQ. Either way, great thought process, and great execution.

Thanks for the kind words!

I went with the mid-bump tilt EQ because I knew I would like it based on previous experiments. It makes it easy to push other gain pedals with it and keeps things form getting harsh or flubby. That said, it's fairly full bandwidth before the EQ stage, so it would probably respond well to different EQs. If you try a SWT control, you might make the high shelf more pronounced. I could also see a Baxandal  or gyrator EQ working out if you wanted more extreme voicings available.

[jimilee]

That looks very nice. A baxandall sounds very intriguing. Oh had been tossing that idea around previously, but never did anything with it.


Sent from my iPhone using Tapatalk