DIY cartridge pedals

[Ben N]

To truly make this experimenter-friendly, (at least some of) the modules need to have access to the guts. That could mean fully programmable digital modules, or modules with small breadboards inside, or modules with a more-or-less fixed topography, but sockets for all the key components, along the lines of the ROG Multiface, or modules with fixed topographies and lots of switchable/variable values, like some of Dano's projects at BeavisAudio.com.

[PRR]

.....players are motivated by:
1) how "Instagram-able" their board is, and how many 'exotic' and hard-to-find pedals they have, be they rare vintage pieces or things from some obscure small manufacturer; there's a competitive aspect;

So, a box with an LCD on top which can be set to look-like "ANY!" pedal, enuff to fool a camera?

Hmmmm, where can I find a "box" with LCD display?



That's my other $39 cellphone "in drag" as a highly desirable(?) pedal. From the side, it fools nobody, but straight-down as for an Instergam post, who knew?

Many other display-box formfactors exist.
https://www.globalsources.com/HD-set/Set-Top-Box-1191607161p.htm
https://www.aliexpress.com/i/2251832590519585.html
https://sg.cytron.io/c-raspberry-pi/c-raspberry-pi-display/c-display-for-rpi-2-3/p-5-inch-800x480-5-points-touch-screen-for-raspberry-pi

Yeah, hundred bucks..... but I didn't hunt, and this stuff comes down over time. If you want a board full of fake pedals you have one CPU/Pi and a bunch of naked color LCD panels daisy-chained-- the refresh rate is trivial.

[Mark Hammer]

Jackson Audio makes an all analog "modular fuzz" ( https://jackson.audio/products/fuzz-modular-fuzz ) that allows for inserting modules into a base, but as good as the modules may be, they are ONLY fuzz, and they are proprietary.  Moreover, you have to take the unit apart to change modules.  So, no quick-change.

The OP was really asking for a common base that would permit multiple DIY circuits to plug into a common base that would permit a) multiple effects to be used at the same time, and b) re-ordering of the circuits/FX.

The only thing I can think of that meets those criteria is RG Keen's FXbus concept  ( http://www.geofex.com/Article_Folders/FXbus/fxbus.htm ).  That said, as forward thinking as it was, FXbus is really more like the Eurorack standard, that adopts a standardized bus for providing power, input and output pins, and some additional pins for assorted forms of control.  Use of a standardized bus, however, says nothing about form factor, or approach to switching.  As one might surmise from all my prior comments, as much as DIY sidesteps the nontrivial matter of who is offering what FX with what features, a form factor that many agree on is one of the critical limiting factors.  NOT specifying a form factor, but only a bus standard, offers flexibility, but doesn't address the OP's desire for plug-in "cartridges".

Eurorack strikes a sort of compromise.  The Eurorack standard specifies a bus, and a few form factor particulars, but is still pretty open.  A module can be as slender or wide as you want (so long as mounting-screw holes align with the rack unit), and stick all jacks and controls where you want on the face panel.  Eurorack does not aim for the plug-in cartridge ease-of-replacement, but one can have as many modules as you want, from as many manufacturers as you want, and sequence them whatever way you like, by means of easily-accessed patch cables.  I.E., it's as easy to pull a plug out from "here" and put it in "there" as it might be to swap cartridges.

[Processaurus]

That said, if you want to try, I prefer the way Biyang did it, with the controls in the cartridges:

Never seen that before, the Biyang system is like a modular pedal dream platform, especially the big one. Certainly some precedent with some of the 80's systems but with the programmable system, and mechanical design, it is impressive. I wonder what it would take to make a DIY module with a 3D printer for the plastic? The latch and the contacts, I wonder if those are obtainable?

[ElectricDruid]

I think this shows why the Sequential ProFX system was so far ahead of its time. Not only did you get to plug whichever units you wanted into the rack, but *their parameters were programmable too*. That's more than that Biyang Livemaster system can manage, since it's basically just a power/in/out bus, plus a basic loop switcher - not bad, but a far cry from Sequential's fully programmable thing.

Since the question of how to make pedals digitally controllable comes up here fairly often, it's worthwhile taking a look at the service manuals for those Sequential effects to see how they did it. There seem to be basically two approaches used there - either CV control of parameters using the CA3280 dual OTA, or direct digital control of levels using the AD7524 Multiplying DAC (still available, but fantastically expensive from AD, cheaper from TI as the TLC7524).

[marcelomd]

Thanks for sharing your thoughts! All great points.

By all means, don't let my thoughts about practicality limit your fun. Fun is the endgame. My engineer brain thinks pragmatism is fun.

[Mark Hammer]

I have one of the Korg PME-40X units and a half-dozen of the modules.  The Biyang unit is kind of a more compact version of the PME40X, with a broader palette of effect types, albeit simpler versions (one of my modules has 12 slider pots!), from what we can see, plus a built-in switching system for the modules.  And, as was true of virtually all modular systems, you have to like Biyang's version of the effects, or else buy a bunch of the external-processing modules.  Of course, once you do that, it starts to become more of a pedal switching system than a modular effects system.

[mark2]

To truly make this experimenter-friendly, (at least some of) the modules need to have access to the guts. That could mean fully programmable digital modules, or modules with small breadboards inside, or modules with a more-or-less fixed topography, but sockets for all the key components, along the lines of the ROG Multiface, or modules with fixed topographies and lots of switchable/variable values, like some of Dano's projects at BeavisAudio.com.

I think this addresses what you're saying, but the cartridges have access via individual connector pads to each of the pot and switch legs, as well as the blend send/return, and in/out, and the other basics.

[soggybag]

The best implementation I've seen is the FoxRox Zim dual drive. You have to open the box to replace the zim cards.