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.

black_current_pcb.pdf
File Size:	235 kb
File Type:	pdf

Download File

black_current.gif
File Size:	69 kb
File Type:	gif

Download File

6 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

5/2/2022 05:09:07 pm

Made this on vero, does not work. Not sure if the resistor values above have changed from the diagram as mentioned above. All I am getting is a clean signal through it. Same with your sonic reducer pedal also.
The only one I got working is the Quantum Defraculator.

Fredrik Lyxzén link

5/3/2022 12:16:27 am

Hi Ed,
The layouts for both this effect and the Sonic Reducer are both verified and built by many people, so there's something about your builds that isn't quite right i'm afraid. It could be a offboard wiring or soldering issue, or perhaps you have bad JFETS. Try replacing the JFETS. Sadly, most JFET transistors sold in through hole (to-92) package are fake these days. I recommend that you get the SMD versions with adapters instead. If your problem persists, please join the madbean forum Parasit Studio section and post pictures of your builds there and I (and other people) can continue to help you with troubleshooting there. Cheers / Fredrik

5/3/2022 07:08:21 pm

Ok Thanks very much for the reply - I'll go over to Madbean. I did use a 2N5458 for the transistor on the Vibrato, should be ok same pin out as the J201. The Quantum Defraculator is awesome and I reviewed it on my channel - Unholy Audio.

Black Current Vibrato & Stutter

Leave a Reply.