CV.OCD vs Mutant Brain vs…

Sorry for bringing this up again…

I recently started my first modular system and plan to use my Octatrack as a main sequencer for it.
Researching the hundreds of options, i read about the Hexinverter Mutant Brain and the CV.OCD. Since the Mutant Brain is sold out everywhere i wondered if there‘s anything the Mutant Brain does, which the CV.OCD can not or of you guys have other recommendations for Midi to CV converter?
Also i read that you can not shift steps off the quantized 16step sequencer, and wondered if this is a lie?:smiley:

Your help is always appreciated.
Much thanks!

Someone correct me if I’m wrong but I was under the impression the Mutant Brain is the “internal” CV.OCD. They use the same editor, I think.

One thing that might affect your decision is that Hexinverter closed up shop.

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If it helps, you may like the Expert Sleepers FH-2. I used to use that with my AR mk2 to sync and send MIDI to my modular. A bit more complex but the web app is super easy to use once you get the concepts and it gives you a lot of power!

I now use the ALM Pamela’s New Workout with the mmMidi and mmT expanders with my Octatrack and that’s great - just worked and especially if you have the Squid Salmple it’s made for it :slightly_smiling_face:

I do actually have three midi to cv converters and even if all of them do what they should non of them is perfect for me.

Mutant Brain
“+” Small size
“-” You need to configure it with a web interface.
“-” You need to transfer the setting over the DIN MIDI port.
There is no usb input which was a problem for me at first
since I had to by an audio interface in order to be able
to transfer the data
“-” Only 4 inputs are configurable for cv or V/OCT … all
other outs are gates or triggers

Vermona qmi2
“+” Easy and fast to setup. No computer needed.
“+” 4 channels each of them has Gate V/Oct and 2 cv outs + clocks
“-” Takes a lot of space in the system.

Expert Sleepers FH-2
“+” Many freely assignable outputs
“+” Small formfactor
“+” Extendable up to a lot outputs (see FHX-8CV)
“+/-” I do the setup via web interface. However in contrast to the
Mutant Brain it is much easier to do so, since it supports usb c
“—” The big drawback (at least for my one) is that some outputs are
very badly calibrated. When setting them to 0-5V I have 4 out
of 8 outputs that do not reach the 0V. The minimum on these channels is
around 0.2/0.3 which is bad since some of my modules need 0V Especially
my ataraxic iteritas sounds very different if some inputs are slightly open.
Even if it looks like you can calibrate it yourself in the manual this does unfortunately
only work for V/Oct outs and not for 0-5V cv.

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FH-2 is definitely the rolls royce of MIDI to CV, I use it primarily with my Octatrack and it’s incredible. Out of the box it gives you 8 MIDI to CV converters with lots of nice options: extremely flexible assignment of functions/voltage ranges to outputs (including setting up polyphonic control with various options to cycle through the pitch outputs), auto-calibration, ability to save and recall lots of configurations of the outputs, MPE conversion, really good smoothing on continuous CV you’ve got from MIDI etc. Added to this are a bunch of extras: clock, arpeggiators, euclidean sequencers, envelopes + lfos (controllable by MIDI CC) - it does so much. And you can add expanders to add 64 extra outputs for 72 MIDI to CV converters in total (pretty good match for all of the Octatrack’s CC controls/LFOS!

Cons vs CV.OCD:

  • Obviously it’s inside your rack so will be taking up precious HP - 8HP for FH-2 alone, 4HP for each expander (though for me it’s saved HP from taking out modulation sources + attenuation I could replace with Octatrack modulation);
  • Probably about twice the price
  • Only has USB midi connection on the module which is no good for the Octatrack (can get a 2HP MIDI expander and use a MIDI to trs cable or any other hub with a USB output)
  • Config tool will take a minute to get your head around.
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Personally I have to keep it small: I use Erica Synths MIDI-CV v2. I like it for it’s easy dual channel configuration. Bastl’s 1983 is also very nice imo.


I’m currently using the Flame µQMCV which gives you 4 channels of gate/pitch/velocity plus reset/clock and one extra mod and pitch wheel output in 5hp. I also grabbed the µ16MCC to add additional CC outputs. These have MIDI thru but I have experienced some odd behavior with it. (if I’m sending clock to one, the second one’s learn mode gets stuck on)

Others I’ve used:

Expert Sleepers FH-2 - enough said about this one, it’s great. Lots of options and you can change the behavior right from the front panel in a pinch, which is nice. Plus any output can be anything including bi-polar. And it’s got a ton of bonuses like euclidean sequencers, etc.

One really important feature FH-2 has is the ability to convert gates to triggers or envelopes. The envelope stages can be controlled by CC, but not via the front panel. But if you have a CC enabled sequencer this can be super useful.

Michigan Synth Works mBrane - a 6hp version of Mutable Instruments Yarns. Again, configurable via the front panel which is handy, flexible output arrangements, good value for size/money/etc. Plus it has a MIDI thru which makes for easy expansion.

Polyend Poly 2 - Tons of outputs and fairly easy to configure, just beware it’s just been discontinued and the clock output goes wonky when making config changes. This isn’t a deal breaker for most since generally you’re not going to change your MIDI to CV routing in a performance but worth knowing.

Squarp Hermod This is a sequencer, but works great as a MIDI to CV interface. It takes up a lot of room, but adds Squarp’s MIDI FX which are a lot of fun in a modular environment. This includes things like arpeggios, scales/quantizers, LFOs, euclidean sequencing, etc.

ALM mmmMIDI Great value / size and dead easy to use. But no way to add more CV outs, just triggers. If your needs are basic this one is great.

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Yes, the Mutant Brain is a licensed Eurorack adaptation of CV.OCD :slight_smile:

Thank you so much for all the replies. Really helpful!! I thought the Mutant Brain is the ultimate thing when it comes to midi to CV via Octatrack and i‘m happy to hear that there are other, even better options. I think I‘ll get the FH2+a midi Socket expansion to connect with Octatrack:)

Thank you!! One last noob question: is there any disadvantage of using a Midi to TRS input, compared to using a full size socket expansion?

The only real disadvantage is you might not have one of those cables lying around, but they’re very cheap and easy to find these days. The main pain in the ass with TRS MIDI is that there are two ‘standards’ (type A and type B) but the Expert Sleepers Tiny MIDI Breakout can be set to be used with both so that’s no big deal. The big advantage is that the expander is only 2HP vs 4HP for the standard MIDI Breakout expander.

You also get 4 jacks on the Tiny MIDI Breakout that can be freely configured as inputs or outputs vs 1 fixed in and one fixed out on the standard MIDI Breakout. So if you have other ES modules like Disting which can be MIDI controlled and/or generate MIDI from CV, you can connect them all up to the Tiny MIDI Breakout and have the required MIDI I/O for them all (you can also, for eg, use one input of either Breakout and connect a Disting’s MIDI IN to the MIDI Thru of FH-2 using the pins on the back of the modules). They claim the tiny breakout will work with some modules by other manufacturers, but I have no knowledge of the extent that it does.

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This sounds really nice, thanks. I
I only use two machines Analog Rytm + Octatrack + modular and plan to keep it that way. With the TRS expansion i could assign 2 midi out/thru to OT and AR individually + Midi in from the OT to sequence modular so one central device clocks them all, without having to form long midi chains.
Also thought about getting the ES9 and route all my outputs (from AR and OT+Modular) into one interface/mixer for multitracking etc. Safes a lot of space and might be a way to start an efficient system!

ES-9 is very cool, but if you already have an audio interface you’re happy with and (importantly) it has ADAT channels consider the ES-3/6/7 combo. All together it gives you 8 ins/8 outs (DC coupled so you can send CV in/out of your computer) in your case, transferred over ADAT to your interface. It can be less of a faff/better latency than setting up an aggregate interface - I use a ES-3 + 6 with my RME interface and it’s great, especially with Ableton CV tools + VCV Rack. If you don’t have an interface, or you do and it doesn’t have ADAT, ES-9 is pretty beefy though - huge channel count if you need all that.

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Thanks. Actually just read a threat on latency issues with the ES-9… so maybe i‘ll just get an external Audio interface then. I have a Behringer UMC4 which has not enough input + sucks with latency and has a bad preamp, so i might consider motu ultralite mk5 interface since it‘s small and portable for gigs aswell

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And has adat channels :smiley:

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Squarp Hermod This is a sequencer, but works great as a MIDI to CV interface. It takes up a lot of room, but adds Squarp’s MIDI FX which are a lot of fun in a modular environment. This includes things like arpeggios, scales/quantizers, LFOs, euclidean sequencing, etc.

Great module for performance, since you can turn midi effects on/off on live, can record incoming midi. Have Hermod for sale since I’m getting out of eurorack. End of sales pitch :blush:

Latency… ??? Blasphemy!!! Never had it. EVER. Where’d you read such a claim???

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