Duo X as USB Audio input and MIDI device | EXPERIMENTAL

I have been trying to make midi work connecting my Duo X Version to a MacBook Pro with Logic Pro 11 and/or Garage Band. I have had weird mixed results, but I am still missing something. I have a Alesis V61 keyboard; guitars and a bass. When the keyboard is connected directly to the computer, that works fine. When I connect the Mod Duo X to the computer as well, I can direct the sound back out of my computer into the Duo X and out to the PA. The sound coming from the computer also gets mixed with the pedals I have active on the Duo X. What I can seem to make happen is the sound(signal) from the Duo X to be sent to the computer. On the Midi Setup app, I have made an aggregate with EShare Audio (not even sure what that is but it has 6/6 in and out); MacBook Pro Speakers; DuoX Playback and DuoX Capture. On the DuoX, I have enabled Midi with the Sudo command and in the Midi Port list, I have tried all the different options, but currently have Enable Virtual Midi Loopback, and Aggregate mode checked. USB Gadget Midi 1 in/out isn’t selected, but it has made no difference when it has been selected.

I know it is just a matter of knowing how/what to do and admittedly I am pretty new at midi connections. But does anyone see what I might be missing or doing wrong? Is the DuoX still receive only?

Yes. From what I understand what you are doing wrong is that you are assuming that MIDI sends audio. That is not the case, MIDI sends…well MIDI. In other words, data. Not audio signals.
To send audio from the MOD DuoX to your computer, either you connect the audio outputs of the DuoX into the audio inputs of a soundcard connected to your computer (either the 2 outputs or the headphones output, although I would recommend you to use the first), either you use the SPDIF output of the MOD DuoX. For this last option, your soundcard should have a SPDIF input.
Nothing here is related to MIDI. Regarding MIDI, you can send MIDI from the MOD DuoX into your computer, load some virtual instrument on your computer or something controllable and play it from the computer.

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Is it possible to use an external USB Audio device like f.e. the Behringer UCA222 to add more input channels to the Mod Duo X?

I’d love to be able to add an extra input for a sidechain signal - the compressor plugins having a sidechain input isn’t very useful without being able to input a sidechain signal into the Mod Duo X :-/

Not yet. It’s been a request by many people including myself.

It’s on the development list as far as I know


Duplicating from 1.12 firmware discussion, as this is probably more suitable place for this piece of knowledge.

  1. Usb audio gadget mode on MDX seems to cause USB connection fails, it was doing the same on 1.11, but at lower rate. Now in 1.12 probability of failed usb connect seem to raise up compared to 1.11, and it might take series of reboots to connect.

Try disabling audio gadget before blaming hardware, buying stacks of new USB cables, etc.

  1. Forgetting to create file that is responsible for windows compatibility caused complete USB connection disruption for me on windows, if audio gadget is enabled.

  2. I’ve just noticed that hardware UI in 1.12 has new menu for enabling audio gadget mode in my MDX : System → Device Settings → USB-B Mode setting. (UPD: only for midi, not audio)

Seems to me like it does the same stuff that was made be creating flag files via ssh/touch, but you can do it without USB connection, and therefore restore usb connectivity by disabling experimental feature, if something has gone wrong with audio gadget.


correct, except we only enable MIDI with this, the audio part is never enabled as that needs more attention.

will give this issue some attention soon.


Just wanted to check in to see if “native” USB audio for the Mod Duo X MDX is in the works?

I understand the Duo X is still on an antiquated kernel…

What do you mean with this question, “native” in which sense?

I mean, will it be an available feature? and is it in the roadmap?

Currently, it’s noted above that it’s not production-worthy in terms of stability, let alone latency.

I understand 2022 was tumultuous for MOD… Any hope for USB Audio being a stable feature for MDX in '23? :grin:


I was successfully sending audio back and forth between my Duo X and my computer (Mac) using the USB-B socket.

I then tried hooking up another device (A&H Xone 96) using the USB-A socket and got nothing. Note that USB-B was unplugged at this point.

I then tried with my computer using USB-B while the other device was still connected to USB-A and got no audio.

So the only case this seems to work on the Duo X is when only plugging a cable into USB-B.

Is this confirmed? Expected?

The DuoX acting as a usb-soundcard is not the same as the DuoX hosting a usb-soundcard.

So I’d say: yes this is expected, you are only using the DuoX as a soundcard itself (which works completely differently from it hosting a separate device).

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Right, that makes sense that you cannot connect two ”devices” without a ”host”. I guess I never considered the various USB ports to indicate host/device. But I get that one of the things you connect needs to set the sample rate used etc.

But I’m not sure I consider any of the devices in my setup a soundcard. So would it make sense for the Mod devices to not be soundcards sometimes?

I’m basically looking for the Duo X to replace a computer in a live setup. And being able to host devices would make it better at that.