Any true stereo circuit (chorus?) to implement after a dual mono drive?

[tegendemuur]

I could take the easy way and just throw a TC electronics Mimiq (the most neutral sound "chorus" I got here) after this dual mono drive circuit I build for myself, and call it a day. But where's the fun in that? True stereo chorus are a rare breed, outside of digital effects... I idid see a lot of typical chorus PCBs though. Has anyone ever tried putting a true stereo chorus together by themselves? What makes these so unpopular in the analog realm? Maybe someone knows about a nifty little circuit that allows for some stereo spread that I could cram inside the dual mono enclosure to make it a more "complete" box?

 

[Aentons]

True stereo essentially means you duplicate all the circuitry so you could put two of the same pcbs in one box

 

[jcpst]

Yep- I thought it would be fun to do something like take two Seabed Delays and use dual gang pots for the level and repeats, and keep the delay time pots individual.

There's also the PCB stereo harmonic trem: https://www.pedalpcb.com/product/pcb466/

 

[Paradox916]

If you you want to go the digital route the, Binaura is true stereo and there are a few different algorithms for stereo chorus out there and if you wanted to go even further down that rabbit hole you can get into the whole SPINCAD thing and don’t even have to know how to write code to make your own algorithms.

 

[tegendemuur]

@Aentons I believe the concept of stereo means that the signal of both left and right need to mingle somewhere in the circuit. Pure left and right will not lead to the desired audio spread effect, like a chorus, so there needs to be some sort of circuit that combines both signals to an extend. In stereo, left and right are not identical. If you got two identical circuits, panned to L and R, it's called dual mono.

​

 

[jcpst]

Well, before this goes too far down a rabbit hole of disambiguating jargon- there is the concept of "true stereo", in which you are creating a stereographic projection, like a binaural recording or an IR reverb.

Outside of that though, if you have two channels of audio, you need two independent circuit paths for them. No way around that.

There are classic tricks you could do though to get phasey/comb filtering sounds, like putting a simple 100% wet delay on just one channel. Literally just delaying the signal line, not like an echo. You get a whole bunch of interesting sounds in the 5-30ms range. If you add an oscilattor to that delay line, bam- classic ADT.

 

[Aentons]

@Aentons I believe the concept of stereo means that the signal of both left and right need to mingle somewhere in the circuit. Pure left and right will not lead to the desired audio spread effect, like a chorus, so there needs to be some sort of circuit that combines both signals to an extend. If you got two circuits, panned to L and R, it's called dual mono.

​

I think dual mono is separate controls for each channel and stereo is the same controls for both channels. Either way, there are 2 in and 2 outs. If you combine the analog processing, it becomes pseudo-stereo rather than true stereo.

 

[LukeFRC]

Stick a pair of shallow water (pedal pcb low tide) and enjoy the differences between each channel?

 

[Bricksnbeatles]

If you mean true stereo output (not phase inverted stereo) then the Aion Blueshift (Boss Dimension C clone) is your best bet. If you need stereo input too, I believe Aion hinted that the Blueshift would be upgraded to a full stereo version later this year

 

[tegendemuur]

@jcpst Thanks! I shouldn't have tried to define the concepts in a hurry while type-walking; I appreciate you correcting me. Adding that delay-line is something I'm going to try, as it's probably the simplest to start out with, and to tinker into something more!

Edit: After some initial searches itlooks like I'll have to go the BBD chip route to get those very short delay lines.

 

[tegendemuur]

@Bricksnbeatles Jeez, how did I only hear about that Boss unit now?! The mono version kit looks like a tricky beast, so I'll better get my skills up and running for when the stereo version hits the market! <3

Edit: then again, I could buy a Waza unit that's been kicked around a bit and transplant its guts into my thing. Probably cheaper as well...

 

[Feral Feline]

Cheaper, but not as much fun as building it yourself.



I LOVE Luke's dual Shallow Water suggestion: If you go with the Low Tide Mini, you could have it all inside a 1590XX.

MORE craziness —
-go with dual-gangs AND a second set of pots, all routed through switches so that you can swap out from global to independent controls
-dual-gang dyslexia: build one channel with all pots pinned opposite — ie when rate, for example, on one channel is dimed, it's at minimum on the other.
-build two different Chorus circuits for each channel: Boss in Left, DOD in right. Or Ibby & EHX, ADA & MXR, ADA & Arion...

 

[Passinwind]

@jcpst Thanks! I shouldn't have tried to define the concepts in a hurry while type-walking; I appreciate you correcting me. Adding that delay-line is something I'm going to try, as it's probably the simplest to start out with, and to tinker into something more!

Edit: After some initial searches it looks like I'll have to go the BBD chip route to get those very short delay lines.

I highly recommend this one based on my test results so far, but for the moment you would need to roll quite a bit of the build on your own: https://forum.pedalpcb.com/threads/digital-bbd-concept-looking-for-comments-and-beta-testers.18909/

Mono --> stereo applications have been my primary testing focus lately and I'm hoping to see the newest firmware version today in my mailbox. Plenty of ways to go stereo throughout, which I intend to start messing with as soon as I have one of the production spec units in hand.

 

[passtheducky]

The Dimension D circuit might be what you are looking for in a stereo chorus.

 

[Robert]

If you don't mind digital, @Paradox916 recommendation for the Binaura would be the way to go.

True stereo in and out (or mono in > stereo out), and you can apply different effects to either side. Flange, chorus, reverb, delay, double tracker, whatever.

The dual gang pots can be split into two single gang pots so the mix and volume of each side can be controlled independently as well.

 

[Paradox916]

analog stereo can be a tough nut to crack there isn’t a ton projects out there, and they can be more expensive and the level of difficulty can go up, not trying to be a fan boy here but the Binaura is truly the biggest bang for the buck in the stereo realm, for its versatility and easy build that you can take as far as you want. My favorites so far this thing can do are stereo chorus, ping pong delays and modulated reverb.. and all these are algorithms that are readily available. If you are into building a diy stereo signal chain this is a must build.

 

[tegendemuur]

So! Much! Inspiration! - Thank you all. I am sure to build two things, just because I can. One will be a banged up Dimension C to which I add an analog dry through. Just a fun little thing. The other one will be one of the PCBs recommended above. So much choice, I have to let it settle to see what offers me the most in terms of making the dirt I'm going for, more immense

So you guys know where I'm coming from: At the moment I have a Parentheses sandwich up and running outside of a box (each with a switchable bass mod, a boost order switch, expression jack, and with concentric knobs, so it can be used in parallel and serial with the same or different settings, without getting too much knobs on there). And, it's my first DIY build... There's no doing things in moderation with me.

Soon I'll start with sandwiching two Mofeta's into a box, but these will be dual gang knobs (there's no 1M value concentric knobs at my shops). Both of these have left and right in and left and right out. So that's where my idea of a stereo end-of-the-chain sauce idea comes from. True sludge madness for my single coil lapsteel (tuned Open D, so it gets into bass territory). The dual inputs where chosen because there's a real lack of stereo in drives for synthesizers (I only have the OBNE Screen Violence, and am I not liking the distortion side all that much, sadly enough). Build-in distortion in synths tend to be too friendly sounding, so I wanted to build a stereo units that could deliver some real sonic power. But then I felt like going full Sunn with the Mofeta. And heck, why not make a total package?! And here I am!

 

[Robert]

I have a small daughter-board drawn up for a fixed phase shift, this is what the DSM Simplifier (and Headphone Amp project here) uses for it's stereo spread function. It's a dead simple way to add stereo spread pretty much anywhere.

 

[tegendemuur]

@Feral Feline Ordered two Low Tide Mini, thanks to the discount that is running on the site, and you. A longer term project, as sourcing will be done in small batches to keep things, ehm... In perspective. Seems like an exciting build. I looked through the BOM and noted 5 regular pots that I can replace with dual gangs to make both left and right run together (at least necessary for the blend and volume controls, perhaps also some of the others). But the Slew has a 1M log dual gang.... A four gang configuration of that type doesn't seem to exist. Is there an alternative way to take command over both Slew settings with one pot, like I could do with the rest? This is to maintain the six knob configuration (or perhaps some will change to concentric - I'll have to see which makes the most interesting configuration).

A crazier thought is to jam a Boss Dimension C right after that in the same box afterwards, but maybe that's gonna be overkill. Just another thought among thoughts living in the back of my head, until all falls in place!

Edit: The inside of the Boss allows for quite a bit of creative reorientation (especially when adding two Buff and Blend boards to allow for stereo analog dry through).

 

[Feral Feline]

I've been looking into multi-ganged pots recently for a project of mine, and I don't recall seeing A1M ... but I'll take another look.


Meanwhile, here's a thought:

One of Aion's projects involves a dual-gang pot hack to get the correct resistance of the original circuit — CHROMA.PDF
Chroma replicates a Boss SP-1 Spectrum: "Balance control requires a dual 10kA/10kC pot, meaning one wafer is audio taper and the other is reverse audio."
In the Chroma docs (Legacy or newer N1 Project), Kevin has a good tutorial on how to swap out the resistance-discs inside the pots.

It would be a lot of trouble, but you could buy a bunch of dual-gang A1M pots, and couple of 4-gang pots and then perform the surgery on them, swapping out the resistance wafers for the A1M.

You'd need to stick to one brand for both the 4-gangers and 2-gangers — find the A1M equivalents for whatever brand of 4-gang pot you purchase. Alpha would be your best bet, I guess.
ALSO note that not all pots can be re-assembled after disassembly.


B100k 4-GANG

4-GANG 50X2 100X2 20MM SHAFT

ALPHA 4-GANG 15MM D-SHAFT B100K

4-Gang Korean C100k

3-5 GANG HERE: https://www.blore-ed.com/product-page/2-45-dual-gang-series-45-carbon-track-potentiometer

4-GANG 2pcs for ALPHA RK12 precision potentiometer quadruple B100K*4 axis length 20MM quad channel MR PENG’S STORE
MORE MR PENG’S

Taiwan Taiwan RK13 sealed precision 4-way potentiometer c50kx4 volume potentiometer shaft length 15mm and a half




If you haven't already done so, I highly recommend reading RG Keen's "The Secret Life of Pots", a few pages so is a quick read.