Hello @gianfranco
Is there any news regarding this noise issue?
Rogério
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hey @rogeriocouto … do you know about the hardware modification that the MOD team will do to help with this issue? i sent my DUO back to have it done. the noise is certainly reduced - enough that i no longer feel the need to use an analog noise gate after the MOD outputs in a lot of situations. however, it’s only ~reduced~ – i.e. i don’t believe the root problem of kernel buffering has been solved.
i asked @dwek about this, with respect to the new DUO X, but he hasn’t replied specifically about that concern.
yes, i agree that it’s a fundamental issue that needs to get solved – so thanks for chiming in! 
i’m hoping that the increased CPU power in the X and in the planned DUO processor upgrade will allow kernel patching which solves this, but haven’t heard about any specific plans.
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Hello @plutek,
Sending the DUO back to Germany is not an option for me.
I don´t think a noise gate as a good solution because the noise is a very specific frequency (F#) and will be present when the gate is open.
The major problem here is that this reduces the Headroom of the DUO specially if you play softer.
This recently became an issue to me because I´ve changed my guitar amp and now I can here it.
Also I get bored of playing C Lydian forever!!!
Cheers
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yes, @rogeriocouto… you’re right that it is a pitched noise, and thus quite perceptible. 
in my usage, careful gain staging plus the hardware fix is usually enough to make it ok enough. also in my use case (only after the hardware fix), the noise is virtually imperceptible under the signal when i use a noise gate.
one thing i have noticed is that it’s somewhat less objectionable when it’s dropped an octave, by switching the buffers to 256 - and the latency is ok for me.
but, yeah, having it really fixed eventually will be a big relief!
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Indeed… the 256 buffer size make it less noticeable. I will see if that buffer size is ok to work with.
Thanks
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I’ve done the hardware mod at home following instructions provided by the mod guys.
It basically consists in replacing a capacitor and an inductance for ones with larger values.
I didn’t have the correct tools for this (the components are surface mounted (SMD) which ideally requires a hot air gun) so went into a scary moment, where I ended up tearing up a bit of the copper from the board (!!!) , but eventually managed to save the situation. The noise is indeed reduced now.
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Is the issue with the noise solved, then?
Does this affect also newly sold devices?
Hi mendo,
We have provided a hardware fix for the users who have asked for the fix. New batches already have the fix.
So yes and yes
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Hi dwek
I would like very much if I could have that fix, thank you very much!
best regards
Bjarne
hi @dwek!
what’s happening with respect to addressing the remaining kernel-related buffering noise, which is still audible (although greatly reduced) after the hardware fix? does the upcoming increased CPU power (in the Duo X and in the proposed Duo upgrade) allow running a kernel which fixes this?
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We still need to check some things, but it is very likely that the new CPU does not exhibit this problem in such a prominent way.
We will have news soon.
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Hi @gianfranco,
I tried the hardware fix that @dwek commented, but the noise is still there (reduced, but still there), so I’m also really interested about what’s going on to fix the kernel buffering issue for the Mod Duo (not X) devices. So anything you can share about it would be really appreciated, thanks!
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So the hardware fix didn’t solve the problem?
I’m having these noise issues too, I suppose it’s the usb-noise thing.
(I’m using the ModDuo since yesterday my first time)
No way for me to send mine back as I’m out of warranty period already. (bought it second hand)
However, the solution AndyCap stated: with a HifimeDIY USB Isolator, it should work ?
Anyone else with these problems tested this solution?
I’m wondering if the Audioquest Jitterbug is doing the same thing?
Another thing: I’m routing my audio out to a Behringer UCG 102 link cable (audio interface) to get the sound to my DAW (Reaper). However, yesterday, after couple of hours doing that without problems, the Behringer interface stopped working (I’m using it already a couple of years now though). I’m wondering if the use of the ModDuo was doing any harm to the interface or not? I guess it was just bad timing.
If you don’t want noise when recording with any device, you need to make sure you don’t have ground loop.
The better solution with the Mod Duo is to use it with bluetooth, and if you have a laptop just unplug the AC cable and work on battery.
Other else you need to invest in some USB isolator.
Another tips : dont turn your guitar in front of your computer when playing (or any electronic device), just do the test you’ll ear a big difference of background noise.
If after all that you still hear noise, it must come from the mod duo…
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Alright, bluetooth is an option, although I don’t like to have too much radiation. I wired my house to make the use of wifi unnecessary too.
USB Isolator is on it’s way, probably by the end of next week. Will let you know if that’s helping.
The noise is only irritating when recording on computer, but it’s nearly a problem when I just put the output through a regular micro-hifi-chain (which isn’t the purpose) but meanwhile I can play and the ModDuo sounds pretty good. I still have to find my own sounds through the hundreds of pedals…
As for the audio interface to connect on the computer, I’m going to work with a Focusrite Scarlett Solo. (should work fine under Linux)
Couple of years ago, when I began this hobby, I bought the cheapest option first: the Behringer UCG 102, it always worked perfect though, but now this product doesn’t get sold anymore in my region, except in one shop where they still have one item… Although the guys in some shops are telling me now it’s not really good material and lots of broken devices are returned, and never repaired by Behringer, no after-sales service. So I won’t take the risk buying that last item another time and upgrade with the Focusrite…
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If what you have is ground antenna (loop) issue then the isolator may work. It all depends on where the loop is. If you are finding that unplugging the USB gets rid of the noise then it’s probably there and an isolator should work. But ground loop can be a very difficult to solve. I thought I took all precautions to not have any loops but somehow I did. I had a great system and then when I plugged in one new piece of gear it all went to shit…
Sometimes it’s just one issue and sometimes it’s multiple issues…
One noise I had was resolved by using balanced cables between the MOD and my mixer/interface. There must have been some noise getting picked up by the cable… bad cable or RF around that area.
Some computers are better at isolating peripherals than others.
Good Luck!
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I’m back, to say that I haven’t experienced any noise anymore, since I’ve been messing around switching cables, resetting all the volumes/gains of in and outs, and definitely: by not using the Behringer interface anymore. That evening, the Behringer interface stopped working, it just broke down and I could wild guess that the noise came from that interface, maybe it was overheated by overpowered signals of the Mod Duo… However I remember having noise when using the mod offline without interface too… Hmm
Don’t want to say anything bad about Behringer, it worked great for couple of years though, but it was the cheapest thing around and I can’t expect it to work for a lifetime.
In the mean time, I bought the Focusrite Solo, and haven’t experienced any noise anymore (so far so good).
It works great on Linux btw.
And today, the usb isolator arrived by post. No need to use it anymore right now, but maybe someday the noise comes back and I can try this isolator to see if it really works.
So yes, I’m quite happy right now.
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A well designed interface makes a difference. I don’t want to bad mouth any gear because noise can be a bad interaction between gear. I used to use the Allen & Heath ZEDi10FX but noticed noise issues with some gear and got different results from different channels. I changed over to the Keith McMillen Instruments K-Mix and it’s been rock solid with no issues. But I would still choose the A&H mixer/interface if I were in the same situation I was back then. Still a great piece of gear for the money but things have changed for me and the extra cost is worth it now.
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I did a test of noise levels on the inputs at different gain stages. Even with headphones pumped up to Max output, I don’t hear noise unless I’m running both inputs simultaneously on high gain. Will post the video when I get a moment.