Rubber Biscuit - Clari(not) with StompLFO

[moosapotamus]

Howdy all! It's been a little while since I've been able to work on stuff. But, I'm finally getting back to it. So, I thought it would be fun to share this before I order some proto PCBs. It's a Clari(not) with a StompLFO and a few added tweaks.

Maybe I missed something, or maybe there's some things that could be done better. Would love to hear any thoughts.


http://moosapotamus.net/images/RubberBiscuitSchSm.bmp

There's a 100k trimpot on the input to the LM386 to optimize for either the clean or fuzz sound, and to adjust for different instruments. And, there is the Fuzz switch that lifts pin 1 of the LM386 for a clean sound.

I'm using an on-on-on DPDT toggle to switch between envelope, LFO, or both. In the middle position it gives a combination of envelope and LFO. The red LED shows the input envelope, and the yellow LED shows the LFO. I'm also adding a blue LED for basic on/off status.

I removed the Tracking control. On the stock Clari(not), starting with both Depth and Tracking turned all the way up, I found that it didn't much matter which one I turned down. Turning either one down gave a very similar response. So, I removed the Tracking control and added a Repeats control. Seven potentiometers was just one too many, and the Repeats control takes it from a single repeat to endless feedback, enabling even more swirly wackiness. Much more usable than the Tracking control, IMHO.

I also went for minimal controls/options with the StompLFO.  A SP4T rotary switch for the StompLFO waveform allows for Ramp, Square, Sine, and Random waveforms. As a modulation source in the Clari(not), a number of the available waveforms sound very similar (i.e. Sine, Triangle, Sweep, Lumps). A SPDT toggle allowing for just Sine and Square would also be a reasonable compromise.

Also, the Offset and Depth controls on the StompLFO are not used. Offset doesn't seem to provide enough benefit to warrant a seventh potentiometer. The Depth pot in the Clari(not) portion is used for overall modulation depth. So, the Depth for the StompLFO is set to maximum, with a 10k resistor from pin 5 up to +5V.

All thoughts, ideas, criticisms welcome. Thanks!

[DeMorhag90]

I don't think anything missing on it!
It's looking excellent, sure it will worked out !

[ElectricDruid]

+1 looks excellent

I like the way that you've striven to keep the number of knobs under control. We don't see that much around here!

Also to use the StompLFO like that without feeling the need to use every feature it potentially has is good. Using a rotary switch and a resistor chain to get the waveforms you want from the selection available is sensible. Triangle and sine are often so close as to not need both, or one sounds marginally better than the other (so why include the "not so good" one?). Squares work for some things and not for others. Etc etc.
As you say, you've got a hardware depth control, so you can easily disable the firmware one. I'd probably have done that the other way around and dropped the hardware depth control and left the firmware one, but that's purely a question of style.

How much modulation depth do you get, and how much does it it need?

[Kipper4]

Very cool Charlie. Thanks on my to do list.

[moosapotamus]

Thanks! Paring this idea down to a reasonable number of controls was a little bit of a challenge. The Clari(not) by itself already has 5 controls... 6 if you add the fuzz switch. Toss in all the StompLFO options and add another switch to select the mod source... it's gettin' mighty crowded 'round here, bro!

Deciding on the depth control did take me a while. I chose to control the mod depth after both of the mod signals get mixed. So, the depth of the two different mod signals can be controlled with only one pot.

I am pleased that the indicator LEDs for both mod sources worked out. The one for the envelope signal gets quite dim when you open the fuzz switch for the clean sound. But, I think they will look nice on the enclosure.

Here is a quick recording from my breadboard.

http://moosapotamus.net/audio/RubberBiscuit01.mp3

The repeats are up high, but not feeding back continuously (until the end  ). The depth is set on maximum. LFO sine wave used throughout. There are 4 parts...
1) Envelope mod source
2) LFO mod source
3) Mixed envelope/LFO mod source
4) gradually increasing Repeats and additional knob twiddling

[ElectricDruid]

Here is a quick recording from my breadboard.
http://moosapotamus.net/audio/RubberBiscuit01.mp3

Abso-frickin'-lutely mental!

Fantastic stuff. Nice work, Charlie. It's utterly insane, in the best possible way.

[moosapotamus]

Thanks, Tom!

BTW, that clip was done with a VTL5C2 installed. I haven't tried any other optoisolators, yet. But, plan to.

Here's my tentative plan for the enclosure...