Parasit studios Sonic Reducer 2.0

[nocentelli]

http://www.parasitstudio.se/uploads/2/4/4/9/2449159/sonic_reducer_2_doc.pdf

An excellent ringmod/aliaser/bitcrusher/sample-rate reduction circuit.

Requires either 3 x TL072 (or 1 x TL072 + 1 x TL074) plus a 4066.

I built and boxed Freppo's version 1 of the Sonic Reducer (which was an improved/updated aliaser circuit based on Experimentalists Anonymous's sample-rate reducer circuit, which the Catalinbread Heliotrope is also based on) but I gave it away a while back.

Freppo's new version 2.0 has done away with the JFET (replaced by a 4066), given the LFO a wider frequency range, and it sounds great on the breadboard. I've tried a few ring mod type effects in the past, but the carrier bleed whining (even on commercial designs like the Heliotrope) usually made them pretty unusable. The gate circuit on this one has a threshold trimmer, so you just gradually turn it up until the whining just stops. When you play, the LFO starts up again, but cuts off as soon as the guitar signal fades out and it is silent.  

[Alex]

To make a layout that fitted in a 1590B box was a real nightmare.
Plenty of links and cuts but it should match the schematic.

[Hozy31]

Hi Alex, missing D5. I presume it goes 3 in from the top left and goes 4  down.

[Alex]

Hi Gavin!
D5 is not necessary.
It goes from +9V to Ground.
I've removed it.

[Hozy31]

Ok, thanks. Building it right now. Hopefully get it done before the football starts.

[Hozy31]

Ended putting CLR in from 9v to four down an added a cut at the bottom left of it.

[clockman]

just finished.
fired right up.
call it verified.
woohoo!

thank you for the layout. going to explore it now.

[nocentelli]

Wow, amazing work Alex. I was going to adapt it a bit and put some fuzz in a la heliotrope, but actually it's great as it is. One variation I have on the BB now is using 33n instead of a 22n in the lfo section to drop the lowest rate down a bit (mainly so i could get it to unison with my low E string)

[nocentelli]

Just started building this (weirdly had only two bits of vero in the stash big enough, and one was exactly 21x18 already!) and I have a couple of observations:
The 22n LFO cap is connected to ground rather than vb as per schematic, but I tried this on the BB and it seems to function ok and didn't sound any different to ground. The cap leg can be dropped down a row to vb anyway. Also, the 4n7 cap on the output of the 4066 should be 47n, and may well sound a bit spiky with the lower value. I actually moved this cap to the space above the 4066 and replaced the jumper with a B10k for a crude LPF control that's nice for further damping the high end.

[clockman]

Nice catch Nocentelli, I will try the 47n cap on the 4066 output and will also play around with the value of that 22n LFO cap. you mentioned 33n

looking at the PCB, I noticed Freppo has included M1 and M2 pads for the sample rate pot. that's his mod board (layout available https://tagboardeffects.blogspot.com/2016/03/parasit-studio-arcadiator-20.html ) going to try that for fun as well.

Freppo, you mad genius, thank you for all you do.

[Alex]

Well spotted!
I've copied the schematic by hand and I've must have fucked up somewhere in the process!
It has been fixed now.

[clockman]

 Alex, just tried the revisions to the layout, sorry but they seem to disable the circuit.
 your first drawing fired up right away.
 I've switched back.. all good.

[Alex]

I've just changed the 4n7 cap value to 47n and sent the 22n cap to Vr instead of ground.
I don't get it. It should match the schematic now.