Noise rendering Mod Duo X unusable

Hmm this statement makes it really seem to be a ground loop issue.
Are you using the same power strip for the Duo and with other devices that you connect via Audio to it?
Have you tried to use balanced cables or a passive DI?


Are you using the same power strip for the Duo and with other devices that you connect via Audio to it?

I tried the power supply received with the mod duo and a 12V set of alkaline cells (hand made). The audio interface is on a desktop computer and connected to the ground, but the same noise appears on my guitar amplifier.

Have you tried to use balanced cables or a passive DI?

With balanced cable yes, it makes absolutely no difference. I have no DI here for the moment.

Does this mean that you have the Duo connected to an audio interface?
Do you have the noise also in a battery supply?

If you manage to somehow borrow one, please let us know about your findings.

Does this mean that you have the Duo connected to an audio interface?

To record the noise yes ! but the noise is here also when the DUO is connected to my guitar amplifier (no change if if amplifier and/or MOD DUO is powered by a battery).

Can you load a generator plugin and with a MIDI controller or using a step sequencer play something?
Basically, skip any input. This will help us understanding if the problem is on the input part of your setup or even the Duo or somewhere else.

I there,

Sorry to bump up a several months old topic, but I seem to have the same kind of problem on my DuoX: low frequency pulsating noise, one every pedalboard. When I turn the infinite encoders, it gets worse (like a scratching noise).

Here is the context:

  • Happens in several locations (pro studio with analog mixer or directly into a powered speaker, and home studio with audio interface)
  • Plugging into a wall or using a battery makes no difference
  • the beating sound occurs when using outputs 1 & 2, with balanced cables or not. It does not occur when I use the headphone/CV output
  • No usb or bluetooth dongle plugged on the device
  • Wether something is plugged into the inputs (audio, CV or midi) or not makes no difference
  • When I manipulate the device and give little taps with my fingers near the power socket, I definitely hear the tapping going through the outputs (as if with a microphone).

I never noticed this before because I used it in a rather quiet environment, and never tried to record anything with it, but it really affects the spectrum between 20Hz and 200Hz.
Here is a picture of a spectrum anaylsis:

The sound is not constant, it’s like a regular fast beat:

My unit was bought rather early, in summer 2020. Serial: MDX-20200817-3-02-001-0164

Please help! :sweat_smile:

I didn’t resolve this and had to send the unit back for a refund.

This is bad news, I’m sorry to hear that.

I read there that there might be a hardware fix/update:

@Mod team: would my unit be one of that “wild” batch? Can it be fixed at home (I can handle a solder iron)? Or should I get in touch with support to arrange a way to send the unit back for a fix?

As far as I remember you also didn’t give us a big chance to troubleshoot your device and understand what was happening. I think it’s obvious that this doesn’t happen with all MOD DuoX users.

I’m not sure, but please reach out to support, add there as well your serial number and eventually a sample of the noise that you are talking about.


Thanks Jon, will do!


Hy, Sorry for the very long reply. The problem still persists on my MOD DUO (see messages from August), I can say it doesn’t comes from inputs, because I hear the noise even if nothing is plugged to the outputs in the patchbay, even if the output is plugged with a symetric cable to a symetric input.
I hear also the noise in the headphones out.

Your description seems that you are facing a ground loop issue.

Anyway, have you reached out to
Please do it, add your serial number and a sample of the noise if you can.

I’m sorry to say this but in my studio I have Pa equipment, guitar amplifiers, effect pedals, multieffect pedals, keyboards, midi controlers not to say more. All my equipment shares the same earth connection and as expected never had a ground loop problem. When I first conneted my Mod Duo X, problems arrived. You tell me, the problem is your electrical infrastructure. So, due to luck,the rest of electronic equipment doens’t suffer with the problem or by some development problem the Mod Duo X, ground is not necessarily a connection to the real earth, but rather is a reference point to 0 Volts? You have to do a little more then workarounds like, using a TRS cable when your amplifier has balanced inputs or putting a DI box in the middle. Ok, that is a a good way to solve the problem in existing units but what will you do in the future?

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Yes. It takes part in the equation certainly.

Not necessarily luck. It may be the case that with all the gear together and with the placement of devices in your chain (both audio and even electric), the MOD DuoX is the one that “shows” the issue. There’s not really a “one solution fits all” here or even a reason. I can tell that just this weekend, I had one gig where we were using a MOD Dwarf and a MOD DuoX, both of them were fine regarding noise without using balanced cables or even a DI, but a hold MacBook Pro used for backing tracks was with a huge noise while connected to the power. This never happened in any other venue, studio, or rehearsal space where we used it.

We are constantly searching, trying, and implementing fixes on the software side to minimize these issues on all the cases that we could pinpoint the reason and find one usable solution. This applies to all production and already sold devices since it’s a software update.
It’s also something that we keep a close look at each product that we develop. But again, more users, more use cases…this results in more triggers for this type of issues found.


Thanks for the answer. I know that you are constantly working to get better. We can see that on the many updates released. My unit it a Mod Duo X Limited Edition from 2019. I didn’t mentioned but, if I remove the ground connection from the power supply plug I have the same effect of DI or balanced cable - no ground noise. Other problem is the low frequency noise on outputs 1/2 when the amplifier is regulated at more or less 50%. The workaround is to regulate the gain stage of DuoX near its maximum and lower the amp gain to minimize it. On the other hand I get more white noise in silent parts of the music.

Unfortunately not all issues can be minimized efficiently minimized by software. Sometimes the hardware rules the game.

All said, you have done a great job with this thing. I love it with all its issues (who doesn’t have one?). Keep the god job.
(BTW I’m happy to see portuguese people like me on the Mod Devices team (am I right :blush:?))
José Mendes


There’s dozens of us! :sweat_smile:


This is actually an important point on this matter. The MOD DuoX LE was a small production edition and, as you probably know, we are aware of some issues that popped up on those units.
Not answering yet on anything of your issue (I can do it later), I’m not sure if you had the chance to read this post from @friedsilence back in November. Let me know if it’s something that you are interested on.

Indeed it is true and your case is actually a really specific one on that. We released a device after that was tackling some of the issues from the LE edition.

:slight_smile: Thank you for the nice words. We always try to do our best. Sometimes that is not enough, but we always try :wink:

haha sim :wink: We are everywhere for quite some years haha
João Neves :wink:

As a good Portuguese joke @falkTX and @XLooper: a lot! more than one!


hey guys… sorry to bump an old topic, but seemed to make more sense than starting again! :wink:

note that i am not referring to ground loop issues here, but rather specifically the periodic low thumping noise that a few folks have written about. with ground loop issues resolved and with good gain-staging, such that both my input and my output signals are close to 0, these noises are at most around -50dB. as such, many folks will have not noticed them and they might be, arguably, within an acceptable range for a lot of use cases – i suspect that’s why this specific issue hasn’t been reported widely.

however, i do a number of things in which silence and low level signals are important, so it has been an issue for me from time to time.

i recently made an important discovery:

if i have a flashing button (i.e. a button assigned to tap tempo), the thumping coincides with the flashes of the button LED. if i change the LED Brightness setting to LOW, the thumping drops about 20dB – that makes a huge difference, and is acceptable for most of my scenarios.

note that there is also a low-frequency “rumbling” associated with rotating any of the encoder knobs; unfortunately no adjustments to the display settings seems to affect that noise. however, it is a lower level and only happens when knobs are moved.

my unit is a Duo X LE. i can’t say whether things are similar on a full production run Duo X.

hope it helps somebody out there!!


…your USB cable is disconnected? @plutek
I have comparable noise only with connected USB cable.

hi @Kim !

at least for me, this particular low level, low frequency thumping happens whether USB is connected or not. …and it’s sufficiently better, both with USB and without, when i change the LED setting to LOW.

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