ForumsHardware ← Call for input: Soundplane to CV module

This year it seems desirable and possible for Madrona Labs to make a Soundplane to CV device. This would be primarily a Eurorack module, but the circuit could also be built into its own enclosure for use with vintage synths etc.

Normally I do most of my design work in private, and only announce a product when it's pretty much done. But we (Brian and I) are going to change it up this time. Because neither of us is that deeply into the Eurorack world, it makes sense to solicit input early on in the process this time. This is going to be a utility device (though hopefully an elegant one) — so before we get too far along, let's make sure it will be useful to you!

The basic idea

USB jack for powering the Soundplane. Module puts out CV / gates / mod outputs for individual touches. Like the Soundplane app, a zone map decides how the Soundplane surface is divided up into notes and what those notes are. You can switch between zone maps, and the name of the current one should be displayed somehow. Aside from this, visual feedback will be at least an LED per Z value. To keep costs low, probably nothing too graphical or fancy.

We're looking for input on things like:

How many voices?

Each voice of touch output will probably have 4 outputs for pitch, x, y and z. Setting up many voices on a modular is not the way most people use them, so I'm guessing that two voices of output will take care of 90% of what people want. We would probably add an expander module for more voices.

Any interesting modes?

A switch that changes z (pressure) into a strict on/off gate might be useful. Any other things like this?


individual voice groups vertical or horizontal? voice outputs at bottom or top? I'm thinking top, because a USB jack on the bottom will go to the Soundplane.


The module will need roughly 250mA at 5v to power the Soundplane. Brian will correct me if I'm wrong. Then there's whatever computing and display the module needs to do, and the outputs. Do we need our own power supply, or a list of compatible Euro power supplies that we can point people to? Any choices in connectivity to make here?

Finally, we're still looking for a great name…

wow, just wow! a dream comes true! i'm very excited to read this announcement!! i just wanted to point to the doepfer a-198 module, the controller module for the ribbon controller. i use that often and i think it's layout might help a bit, here is a picture of the module:
the upper half is for the pitch cv, you have a gate output and a scale knob which sets the span for pitch (from just a few semitones to several octaves). the lower part is the pressure output,a second gate output with a threshold control and again a scale knob for the pressure cv out. i think the combination of the pressure cv and a gate or trigger output is really nice and maybe better to have both at the same time rather than a switch... two voices are great, four are better! but your idea for an expander is also good.
i'm not that technical, others will help more.
again, i'm very excited about this!
a, planeuro, europlane, cntrlplane, e-plane,, i don't have a good name...:) sorry for my broken english, cheers!

I sent a couple of comments to you in a private email. This is a great idea for a project. I wish I had a Soundplane so I could use the module when it's available!

For extra functions -- I don't know how instantly responsive the Soundplane's data output is, but you might consider a built-in lag processor to smooth the voltages just slightly. One global knob. Just a thought.

I'm still new to the eurorack approach and have only recently started using some modules by Makenoise. It's a lot of fun and I think a very interesting way to make music.

Monome's approach to connecting their 128 grids to their new eurorack modules is quite interesting to look at. This is especially so since they are also looking into ways to finally move away from depending on a computer. As a performing artist, this is something that I really value (I dream of being able to have a wide set of expression possibilities in electronic music without needing to have a computer on stage anymore).

One idea of theirs that I like is that it is possible to disconnect their input hardware from each module, and the module would "continue" doing what it is was doing while the 128 grid was plugged in. They also have some interesting solutions relating to the voltage needs of the modules/grid input.

250+ mA is a lot to take from the 5v buss. I would suggest trying to use a regulator and take it from the +12v. There are a few threads about this on Muffs and a few DIY folk have done it already for their modules (I can dig up specifics if you need links).

Other than that - dont make it SoundPlane exclusively. ExpertSleepers has just done a USB host module and Mutable Instruments have the CV Pal. If folk that dont have a SoundPlane can use it your not limiting your market to a)People with a SoundPlane b)people with a SoundPane and a Eurorack who want to use them together. There are a lot of iPad and android users out there - x, y and z work on those devices too :-)

Finally as its for SoundPlane I'd call it the Madrona Airport.

I agree with mckenic on the 5v draw issue. Some people don't even have 5v available in their racks.
You might take a look at Vermona's Quad Midi Interface for ideas
While it's a space issue for some racks, it provides a lot of possibilities. Most of the midi interfaces don't provide this many options.
Have you ever given thought to a smaller, less expensive version of the Soundplane? I would buy one ;)

I have a large eurorack setup and often use my soundplane to control it via expert sleepers silentway software and ES-3. It is a challenge to setup and often doesn't work properly so I would very much be interested in such a module.
The primary feature request I would make is a mode whereby voices are mapped to zones, rather than by order of finger press. In the modular world it is rare to have polyphonic modules. I find having multiple voices active on my soundplane makes it unplayable with my modular because the fingers have to be placed in the right order for the CVs to come out of the correct outputs. 2 voices is manageable but that's it for me. It would be far more useful to have the soundplane divided into different zones, each controlling its own voice. For example, the 5 horizontal lanes could become 5 individual 'ribbon' controller voices. Or the soundplane could be divided vertically down the middle to create 2 large X-Y control pads. Having multiple 'presets' of these different zone/voice combinations to choose from would be very useful.
The most common way I map the soundplane when performing with my modular is to have 1 voice active and CV outs from X, Y, Z along with quantised pitch and gate outs. The gate out on note press is a very useful feature for triggering percussion. I then use the remaining ES3 outputs for weird blends of these CV's to be used as semi-random modulators. My most common patch is X controls pitch, Y a modulator of some kind, and pressure (Z) opens the VCA.

I also agree with the others above that drawing too much power from the 5volt rail can be a problem. I have two of the monome modules and several monome grids and since I don't want to risk overloading the 5 volt rail I use each grid with its own power supply and a special usb adapter sold by monome. It's not a very elegant solution and if the same is required with the soundplane then I would recommend having the option to plug it into the rear of the module (like some of the trogotronic modules).
Happy to be contacted if you want further input.

I have an MS-20 mini that I have been driving using MIDI. I'd love to drive it with CV and get the computer out of the mix. I have also been drooling over the Kilpatrick Audio Phenol. If the proposed box had voltage scaling for dealing with various conventions that would be fantastic. Also to agree with supergregg that some ability to configure the box to deal with each person's preference for multitouch setting and voice allocation would be essential to making the box useful.

For devil's advocate, Doepfer has the MCV24, which seems to have quite a lot of features for converting midi to CV and is reasonably priced for the wealth of features and outputs it provides. Maybe a great midi box made to work well withe the mcv24 or something similar would have wider appeal here?

I'd be happy with any solution that removes the computer and does it well, meaning reliably and with sufficient configurability to tweak polyphony and touch settings.

ooooohhh... Ive been avoiding modulars, but this might tip me over the edge :)
id echo @drart comments, id really love a box to allow my SP to be computer free, perhaps a separate CV + midi box might widen the appear to other analog (and non analog) synths.

The Soundplane draws an average of 300 mA when active. It draws 80 mA when first connected, before the power light comes on, but it's not terribly useful in that temporary mode (which is required by the USB standards).

We'll definitely design the Soundplane Host so that it doesn't overload the typical power supply, although it might take some investigative work to find out what level of power supply most people have, versus what they'll need for the Soundplane.

Stay tuned!

This might make me finally get a Soundplane. I'd recommend posting on the Euro forum of Muffwiggler, I'm sure people there would have great suggestions.

Paul Schreiber of MOTM is developing a 4 oscillator version of his e340 / e350 modules that I am especially interested in using with the Soundplane.

Though I don't have a Soundplane yet, I think MIDI output box would interest me more (to drive hw synths without the need for a computer).

I'm totally into this! How would zone maps be uploaded? Would there be a USB device jack as well as the host port? Or could there be a Soundplane firmware update that allows zone maps to be stored on the Soundplane itself?
I also second the devil's advocate MIDI interface idea. There are plenty of great existing MIDI to CV hardware devices out there at the moment, and using MIDI as the basic protocol might allow for more customization to individual needs for this kind of thing. Of course, the sacrifice would be the usual MIDI pitfalls of bandwidth, quantization, etc. Either way, I am super excited about the possibility of a computer-less Soundplane!

I'm very excited to hear this as well. I don't (yet) have a SoundPlane (hopefully we will see another run this year, to coincide with the release of the module?), but I do have a little eurorack setup and it would be great to have a direct connection.

In terms of layout I would prefer vertical voice groups to keep the width of the module to a minimum, and I think that having two voices is sufficient (with an option for expansion).

I personally am far more in favor of CV with tight SoundPlane integration and higher resolution data over a MIDI/general purpose design. As several people in this thread have mentioned, there are already a lot of options for general purpose MIDI interfaces and CV to MIDI.

If I had one trivial wish I'd like to see the jacks used on the latest Expert Sleepers modules (assuming they're not proprietary). Besides looking nice IMHO, I find the visual indication of voltages quite handy.

Our current idea is that you can edit zone maps on a computer, then download them to the module. On the module you can just select them. Cable-wise, I think Brian had something clever with a USB A->A cable in mind. I could be wrong.

Or could there be a Soundplane firmware update that allows zone maps to be stored on the Soundplane itself?

This is kind of a genius idea, but the Soundplane doesn't have any NVRAM.

I'm not super into the MIDI interface only idea because the really special things about a Soundplane + CV system would be lack of gear-bloat and a really fast, high-resolution connection between gesture and voltage. There could be a MIDI out though—if not in the initial module, then in a future tabletop device.

The great Expert Sleepers jacks were created by Os himself. I think we have to pat him on the back and leave those to him!

This might sound trivial but I really think the module shouldn't have a display.
I specifically pick my modules to avoid displays in my system as it gives me more of a "real" instrument approach.
It's not just an aesthetic reason, but also a functional one (knob-per-function instead of menu diving) and I really think this is the same philosophy that lies behind the Soundplane and should be carried out into the module.

On a side note, I agree with the two voices choice: more would be overkill for most people and for the rest a simple 4hp expansions (8 outs, hence 2 extra voices) would be a no brainer.


this is great news .

I agree with Timoka : "i think the combination of the pressure cv and a gate or trigger output is really nice and maybe better to have both at the same time rather than a switch."

I too would probably get the expansion for four voices but two is fine for the base module.

"Our current idea is that you can edit zone maps on a computer, then download them to the module. On the module you can just select them."

One should maybe only have a button (scrolling through the zone presets) and a small display with a preset number.
The zone description could be done on paper (a drawing of the soundplane) .

This is how I do it with the Nord Micro Modular and it works great.

I wish you all a nice day here from Yangon !



Since pitch CV has been mentioned, I'm assuming you are referring to 12TET 1v/Oct.

How feasible would it be for this module to be able to download zone maps that interpret Scala files similar to Aalto & Kaivo's KEY module? This is really important. One of the most satisfying parts of using the Soundplane with Aalto and Kaivo is the ability to utilize Scala files with a continuous surface.

@saemola, so, the opposite of this then? I don't know, I think it's pretty tight.

It would not be too hard to put some oscillator code in the module and have a mode where it would output oscillators instead of pitch CVs. That might make people want tons of configuration options that wouldn't have come up, otherwise. But it seems too useful to pass up if the CPU in the module has the power.

well, don't know about "opposite", just something without a display.
I understand that the presence of a display is a completely feature-driven choice.
some features might be hard or impossible to implement without a display, but as far as a simple 2-voice output module, I think it could easily be left out (heck, there are wavetable oscillators lacking displays).
also, price would certainly benefit from it.
again, it sounds like you want this module to be more than just an output utility module, so the presence of a display might be something to be considered further down the way when things are more clear.
just pointing out that I'm not a fan of displays and that my (other people's) modular is purposefully built avoiding display-centric modules.

curious to see what else will come out from this discussion.


Thoughts on a Scala interpreter for the module and pitch CV?

Yes, good point about getting other tunings in there. If the module continues the Aalto / Kaivo way of doing things, then there will be a separate selector for tuning tables. We'll see if this is feasible or if it should get hacked into the zone map somehow.

This is absolutely brilliant news!

I think VERY important is duplicating the top row buttons from the, especially "Quantize". This would be hard or even impossible to realize with a Eurorack modules otherwise. You could use quantizers to quantize the initial note pitch, but then you couldn't do vibrato later.

Here's a (possibly dumb) idea-- how about a Bluetooth chip in the module? While it would add a little to the cost, it would also enable direct transfer of zone maps, tuning scales etc, and maybe some live diagnostic information back to a computer (or tablet??), while mostly eliminating the need for an integrated display. Not that I am necessarily against the display; I like pretty colors.

This Bluetooth idea is good. It would certainly be cheaper than an OLED display! The disadvantage would be that you need an iPad or something for calibration though, and then I would have to write that app... still intriguing though.

Speaking of iPad, I'll just throw this idea out there, out of ignorance: would it be a whole other bunch of work to make the module compatible with other USB controllers or with an iPad? Kinda like the Expert Sleepers FH-1.

apart from this project is going to involve me going down the modular rabbit hole, I'm really excited by it :)

a couple of thoughts

  • iPad/Bluetooth
    this discussion scares me, Id get a modular to get away from computers, Im not keen on integrating them... am I the odd one out on this?

  • KISS,
    Id really love it to be simple, and do one job really well, direct connection of the soundplane. Im sure the architecture will be open to expansion anyway, so no need to over complicate at the beginning? keep it simple ... conquer the world later.

In this vain, Id have thought something like:

  • micro controller with limited storage (need for SP touch tracking software - no?)

  • upgradeable firmware via USB, and also allow upload of small files (e.g scales/zones), or possibly this could be done via micro SD, but not sure a slot in a non-clean environment is good option, also adds cost.

  • open source firmware

  • 8 CV out, default assigned to 2x X/Y/Z/Gate BUT by assignable to whatever via firmware (so future firmware could have zones which use as 8 faders)

  • 2 endless encode with small readout to show values, addressable via firmware (example use might be to change scales/zone mapping)

  • 2 CV in (by default, drive the endless encode values)

  • expansion connector to allow for additional banks of CV outs etc.

Note: Number of CV outs/in I guess this will be driven by cost, and keeping the module 'affordable', which was stated as the goal.

with this kind of model the initial firmware could be very simple (and rock solid!), but could could easily be extended to cover different zone mappings/scales, or other imaginable uses.

open sourcing the firmware, could help relieve some of the pressure on ML.
ML is really creative and is always coming up with fantastic ideas and products, so Im sure we (users) have to be realistic about how much effort can be put into this project (without letting other ML projects suffer)

I'm planning on starting a modular this summer. If you end up making this module there is 100% chance I will buy it (and the expander), Echoing everyone else, the ability to use my soundplane without using my computer is very appealing. Part of the reason my soundplane has been sitting mostly unused for the last year is because I'm too lazy to boot up Ableton and plug everything into my computer.

Hello all! Great comments so far. I've been remiss in not checking this forum more often.

I logged in to ask how much modular real estate people are willing to devote to a Soundplane-to-CV converter. The A-198 is 8-HP, the qMI is 24-HP, and those MOTM are 14-HP. The absolute minimum base model would be USB-A plus 8 CV jacks, so 8-HP would be a tight fit. A monster with an OLED per voice could easily grow beyond 24-HP and take a whole rack. What do people want?

I worry that throwing too many features into this will end up turning people away, who either don't have the space or who may actually be at odds with the aesthetic. Another consideration is that every feature takes time to develop, even if it only adds a few dollars to the bill of materials.

Here are a few things that won't be in the product:

1) Bluetooth

2) abuses of USB connectors that violate the specifications

3) unkeyed modular power connectors

4) tiny USB OTG connectors that belong on a cell phone

The Bluetooth industry is dominated by products that barely work because everyone wants to make the cheapest module. They're a serious headache to develop a professional quality product with, and they often don't have all the features listed in the data sheets. Personally, I think that it would be a bad idea to put radio signals in a module, unless you actually want to synthesize radio signals.

USB offers many tempting options for remote configuration and firmware upgrades, but there is a better solution that makes USB moot...