Release 1.9.0

Hi there everyone, the stable release of v1.9 is here - v1.9.0 aka “Automation as a Service”.

This is a new feature release, with focus on CV support and improving the user experience.
There’s also many fixes as usual.
The list of new features was posted on the 1.9.0-RC1 announcement, but let’s go through them again.

CV support

This is mostly concerning the Duo X.
The physical ports now have their software counterpart displayed in the pedalboard.
There are 3 inputs - 2 for the CV inputs and a special expression pedal one.

The expression pedal input (on the pedalboard) will output either 0 or 0-5 depending on the device settings.

On the Duo X device menus, there are now options regarding CV.
For the inputs, a switch for toggling between CV and expression pedal mode. (CV by default)
For the outputs, a switch for toggling between Headphone or CV. (Headphone by default)

There is also the setting to toggle between signal on ring and signal on tip for the expression pedal.

Addressing arbitrary parameters to CV out ports

Related to the previous item, it is now possible to address arbitrary plugin parameters to a CV out port.
This is the case for both hardware and plugin CV ports.
It is also possible to address multiple plugin parameters to the same CV port.

You can manage which CV out ports are addressable by clicking on the “Manage CV Ports” button on the top of the pedalboard constructor window,
and then enabling specific CV ports that you want to use.
You can give them a custom name so that they are more recognizable.
Then in the addressing dialog, you can pick that CV port from a dropdown list.



Smooth peakmeter color transitions

We have found that the way the peakmeters are used often confused new users and as a result many didn’t play with the optimal gain settings and headroom.
We have decided to tweak things a bit and also make the transitions between the colors smooth instead of static.
With this, the LEDs will also give a better indication of where in the range the signal is instead of being in one of the 3 options there were before (green, yellow and red).

So in v1.9 onwards, the following ranges are applied:
-inf dB to -40 dB -> LEDs off
-40 dB to -6 dB -> green fade in
-6 dB to -1 dB -> green fully on, fade in of yellow
-1 dB to 0 dB -> red

When the value reaches anything above 0dB (digital clipping) the LEDs will blink red just as they did before, to give a clear indication that the audio is being distorted.

Other notable mentions

  • Duo X potentiometer calibration mode
  • new compact pedalboard list view
  • show MIDI program number/indexes near snapshot names
  • fix MIDI DIN handling of active sensing and running status messages

Visit to see all changes since v1.8.

A special note:

This release is enabled as an auto-update only for MOD Duo X users only.
We are in the process of making a dedicated release for the Duo, in where we make changes in the kernel to allow it to be updated more safely going forwards. (basically, we are going mainline :rocket:)
So while Duo users do not get much from this release in particular, the next one is going to be focused on it. We want give better support for Duo, specially NAND units, by making them more reliable.
Duo users can still install v1.9, but it has to be done manually.

The next time you open the MOD Duo X web interface you’ll receive an update notification.
Just click on the tooltip icon in the bottom-right when that happens, then ‘Download’ and finally ‘Upgrade Now’.
Wait for a few minutes while the MOD updates itself automatically. :slight_smile:

Duo users can manually upgrade to v1.9 by downloading the image file and following the update instructions on the wiki releases page.

We hope you’re enjoying your MOD Duo and/or MOD Duo X.
Let us know if you find any issues.


Thank you for the hard work @falkTX and MOD team. Collectively, some improvements over the last few releases have made a big difference in the usability and enjoyment of my Duo:

  • Noise reduction
  • Select snapshots via PC messages
  • Peak meter LEDs
  • High-quality amp/cab plugins, and many other new and exciting plugins

The news about the (upcoming) mainline kernel integration is so exciting and sounds like it will improve stability and future upgrades.


Thanks for the continued releases - it is much appreciated!

Is there a description of the capabilities of CV and what we can do with it somewhere? It looks very intriguing. A wiki page with some real-world examples would be nice. For example, you mention expression pedal mode - what is that and how is it different from CV mode? Can I make an expression pedal out of a simple potentiometer? I’d also like to know what the pinout/electrical characteristics of the CV input is so I know what I can plug into it without damaging my unit.


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Congrats @falkTX on getting CV done!

I’m going to try ASAP seeing @unbracketed comment on noise. I’ve stopped using mine as the processing noise was so bad. Fingers crossed this fixes it!!


Sadly CV is one of the most variable ‘standards’. While you’re waiting the official response you might like to read this -

There is some info on

On the current units, you can send 5v to the inputs. The headphone jack can act as cv out, but it is set as headphone mode by default (it is a switch on the device menus)

Expression pedal mode is a switch on the inputs.
It makes one of the CV inputs actually output 5v.
This is to that it can drive, well, expression pedals.

The “CV meter” plugin is very useful to ensure things are working correctly.

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What’s a NAND unit?

Steve, have you got the K-Mix and the Duo plugged into the same computer? If I do that, to edit patches, I get hella noise. But if I either unplug the Duo (or X) from the laptop, or plug into a different laptop, I’m fine - there’s a ground loop thing happening between the USB sockets…

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Hey thanks Steve. No it’s just the Duo X into my PJB bass amp and noise is same with or without USB pluged to computer.

Thanks for the suggestion tho’. I’ll watch out for that.

Hi Steve,

I had the same issue, tried one of these, problem solved.

NAND refers to the type of flash memory used, like for those in a usb stick.

On newer Duo models we changed from NAND to MMC, as the latter is much more reliable.
We have a way now to make the older units flash memory much more stable, leveraging some tricks that a new linux kernel allows (it was simply not possible/available back when we first started development on the Duo).
So going forward, we want to have the older units using the new kernel and drivers. As file handling is coming in a later update in the year, it is crucial that access to files is as stable as possible (even more than before)

We will have a lengthy forum post about this closer to release.


Thanks, @falkTX!

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how do I know if my unit is NAND or MMC? (I can do ssh if needed)

I started getting some issues after restarting after the upgrade.

Did $SOUNDCARD changed?
I saw that systemd startud hanged on mixserver.service and after digging a bit into it I realized that it was failing to access the soundcard,

/usr/share/mixserver/ printed “Can’t open ALSA control device.” (It’s pretty cool to be able to look at this :slight_smile:)

The env variable was not set on my shell, but on the script it defaulted to MODDUOX, which won’t work
as aplay -l only lists DUOX. After setting it on the systemd unit I was able to get past it,



mount -o remount,rw /dev/mmcblk0p2 /
cp /etc/systemd/system/mixserver.service{,.bak}
vi /etc/systemd/system/mixserver.service  # Add that Environment line
systemctl daemon-reload
systemctl stop mixserver
systemctl start mixserver
mount -o remount,ro /dev/mmcblk0p2 /

I think that this name just changed unintendedly as many other
things just refer to MODDUOX, like the webserver which I figured after finding a bug in the
UI as some request to set up some knobs was failing.

My screens are also not working :frowning: . I guess I can try and add that environment variable
everywhere just in case (or figure out how to rename the soundcard?).
I haven’t tried re-imaging again yet, but I’ll guess I’ll just go that route tomorrow.

The mixserver service is not supposed to be started unless you specifically enabled it in the web gui advanced settings.
The top of the service file has this:


In any case, this is a legacy service we do not use anymore, we just keep forgetting to remove it.
So we will do that now.

It is not that things got renamed, we just never bothered to fix that service because it is off by default and simply unused at the moment.

Oh, I didn’t meant that the service got renamed, but the sound card

I know, I understood that. The bad name comes probably from initial testing of ours trying to make that service work for Duo X, and then just leaving it behind.

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I just flashed the new modduox-v1.9.0.1220.tar into my ModDuoX and the screens are still stuck with the [MOD DUO | X] logos and I can’t assign knobs on the web UI.

The restore was successful as I recovered the broken behaviour of the mixserver unit (the service doesn’t matter, but it confirms I’m running the new image). I’ll give it another try, but not for too long as I really wanted to practice some songs, so I’ll revert to v1.8 if I don’t get any leads.

How do I know if my unit is NAND or MMC? What do I need to check?

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