Black Current Vibrato & Stutter

7/31/2014

Here is an original design that I have been working on for some time. It's a combined vibrato and a stutter effect with minimum controls. I'm very happy with the results and I hope you like it. :)

The idea is simple: the signal is split into two paths that are out of phase. One side is goes though a highpass filter (that cuts eveything below about 500hz) and amplitude modulation, then both signals are summed back together. As the two signalpaths partly cancel out from 500hz and up, this creates an interesting phasey sound in the crossover frequencies - a vibrato'ish sound that is a bit different from your standard tremolo.

The stutter mode was added later as an afterthought. The way I set up the VCR (the JFET acting as a voltage controlled resistor) results in a very agressive amplitude modulation, so I wanted to take advantage of that in the design.

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3 Comments

Jacob

6/28/2017 02:28:16 am

Hi, super cool pedal!

Is it possible to relax, or adjust the depth of the vibrato (i.e. not the studder) effect of the pedal? Like perhaps throwing in a trimpot or something?

Don

12/21/2020 06:27:31 pm

I’ve build some weeks ago the strip board version and didn’t work...... debugging for a while, i didn’t notice bad or missing cuts/ bridges, cap polarities etc etc. ... after a fustration times , i decided go to the pcb etching.... haha i didn’t succeed... after 2 attempts i noticed that my ferric chloride was to weak, as was used several times... so i just got a slight pcb etching... after that I decided to take my dremel rotary tool and follow the marks that the bad etching left and sort of “engrave” the pcb

Bingo! Pcb ready... so i unpopulate my unsuccessful vero board and populate my new carved pcb and noticed that the problem was 2 wrong resistor values ( so i believe vero board attempt will work fine, and avoid all frustration and extra work , if I’ll re check those resistors carefully ) lesson learned :)

Anyways.. the pedal now works amazingly and i fucking love how different it sounds , to any tremolo I’ve play/heard!!! Thanks for this great and fun circuit (among others I’ve build from you) big fan!

Only question here is : if theres a way to tame the thickin noise coming out of it ? I must say that doesnt annoy me by playing guitar with it .... but i found other applications for it and sometimes that thicking noise could be a little much

Anyways. Thanks a lot again for the great stuff you do!

Fredrik Lyxzen link

12/22/2020 05:35:58 am

Hi Don!
Thank you for the build report and the kind words. I'm happy to hear that you finally managed to get it working, and found the incorrect resistor values aswell. That's an easy mistake to make. :)
Regarding the ticking, you could try to add more DC filtering on the power supply rail, something like a big 220-470uF capacitor. It could also help to keep all the wires as short as possible and to use grounded wires on the input and outputs. Cheers / Fredrik

Black Current Vibrato & Stutter

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