Eurorack video modules to compliment Mainbow?

Hi, my gateway to modular video has been a Chroma Cauldron Mainbow v2. It has four oscillators that generate LZX-compatible CV. I’ve incorporated it into my overall system that mostly sends signals around as composite video (between several Underscores modules, Roland V-8 mixer, etc).

I’m looking for suggestions of other Eurorack video modules that I could incorporate into my rack that would compliment the Mainbow? It looks like most LZX modules require using their sync system to connect all of the modules, but the Mainbow doesn’t have a way to send or receive sync.

One strategy may be to have an LZX type of system at the beginning or end of my chain, just connected to the Mainbow with composite. But I’m more interested in modules that can be patched into the Mainbow signal chain to add some more interesting options.

Any suggestion on modules from LZX, Syntonie, Foxing Hour, etc, that can compliment what I already have without totally “starting over” with an LZX sync based system?

What do you miss or looking for (because also the V8 offers a lot of FX, keying etc.).

Are you looking for generative approaches? Or for other video sources (Hi8,VHS,DVD) to be mixed with your Mainbow?

Erogenous Tone’s Structure offers so many opportunities and FXs and can be seamlessly integrated into the lzx world. It also has a composite input, so you could mangle Mainbow input into Structure.

I also thought about similar things, but getting from composite into lzx standard, probably requires a TBC2 for decoding and an ESG3 for encoding The combination is awesome - but not cheap.
(@all - please correct me, if I missed something here or am simply wrong!)

So - maybe staying in the composite world could be an option?

  • Mainbow
  • ET Structure (has also switchable CV inputs - so you could use relatively cheap eurorack oscillators for modulation - or Structure’s internal OSC).

Synthonies CBV 001 and 002 are cool eurorack composite glitch modules.
Nevertheless: I like my Mezkaline glitch units much better, as they offer far more possibilities.

Finally, I decided to go for a mixed eurorack / external setup as it is far more flexible - and much cheaper :innocent:



I’ve already got alot happening in the composite world. I’m looking more for generative type of things that could be added in the middle of my Mainbow signal chain. Since its function generators are sending LZX compatible signals, I’m trying to figure out what other modules might be able to add something interesting to what I can generate.

If you’re looking for modulation of the 0-1v signals then there are a bunch of modules by syntonie that will do that. They come pre-built or as DIY kits.


Otherwise you can modulate things at LFO rate with most standard eurorack sources combined with a 5:1 divider or more roughly with attenuation. A Pam’s outputting at 20% gives you 0-1v and has lots of possibilities.

Do you have a modulargrid you could share?

Mine is mostly composite too:


I used my Mainbow with external modules such as the LZX Cadet Hard Key and my own (reverselandfill) BLUR & SNOW to add features and effects.

I also used the Syntonie CBV001 to add extra glitch effects with good results!


Actually, you can use one of the Mainbow oscillator RCA output to provide sync for modules that requires it, else a video distribution amplifier to split the composite output of Mainbow to send it both to your display/capture and to the modules that requires sync. The advantage of RCA sync over previous sync standard used by LZX modules is that you can feed a complete Composite signal (or Y from Component) as a sync source. I tested LZX DSG3 with Mainbow and it worked nicely. To give an example of this, here is a video where I send the external source Composite output to both CBV001/CBV002 and to oscillators that requires sync

Then, beside a couple modules from LZX that uses sync for frame synced switching (to avoid frame tearing, when it switches in between two frames), sync is mostly used for signal generators modules, and since Mainbow already has 4 video rate oscillators, I would probably focus more on complementing it with processing/mixing. Then maybe going for a dedicated LFO like VHS Baja, VU006 or Animate would make sense to free up the video rate oscillators from Mainbow to do HV shapes/modulation instead of using them as LFO.

You can see Mainbow as your sync generator/encoder, and then any 1V/RCA sync compatible module can be added to it, so no need to start over your system :wink:

Mainbow has built-in wavefolder/rectifiers at the HSVA inputs (iirc max setting on each of the inputs is 3x time folding) so rectifier based modules such as LZX Staircase/Stairs, Foxing Hour RECT, VU002 or Solaire might be a bit redundant with it. Then to have voltage control over the folding, you can use a VCA/Multiplier on the signal you send to the HSVA input and set the level know to max setting on the Mainbow, Cadet Multiplier or Factors can be used for this.

Also, Mainbow has built-in mixers for each oscillators, so a simple mixer like LZX SumDist, Foxing Hour A+B-C, VU010 or Solaire is not really needed, then a Matrix Mixer can be nice, Reverselandfill Matrix Mixer is really great, been using it in a RGB setup just before my encoder to finely tune colors, though it could be really interesting before the Mainbow HSV inputs I think. A mixer with attenuators like Reverselandfill CMIX can be great as well, would give you more control over the mixing. Then, as your system grows with more generators/modulators, more mixer can be handy, rinse and repeat.

About key generator, Mainbow HSVA inputs can be toggled to either straight input signal or keyed signal, giving hard edges instead of gradients, though the threshold is fixed, so a dedicated hard key generator like LZX Keychain, Cadet Hard Key or Seuils can be nice to have manual or CV control over the threshold.

Else, if you dig the aesthetics of logic, the whole Castle series is really great, you can use the oscillators from Mainbow to clock the modules that requires a clock input. The Castle Clock VCO requires sync over 16pin power cable or front panel jack 1V, you could use an osc from Mainbow to sync it, though it wouldn’t be that different than using square/pulse output from Mainbow directly. I really like the look of ADC based modules (Castle ADC + DAC, LZX Ribbons or Isohélie), give that old school posterize effect.

Processors like LZX Proc or Foxing Hour Access can be really handy, even if those look simple at first glance, they can be used to invert and/or attenuate signals, which can either give more control over the final output if used before the HSVA encoder stage, or to mix H and V synced oscillators at different ratios to modify the resulting 2D shapes.

Reverselandfill Triple Function Generator can be a nice one to process signals also.

Then it’s hard for me to give a specific answer like “you need this module and this module” as I feel like any module can be useful depending on the context, what look you’re trying to achieve, etc…

So to summarize, I would add more processing modules first, then a tiny bit of mixing, and later on, more generators such as oscillators/ramp generators.