Mmmm… I think I have exactly the same 375Hz problem with the Dwarf, with any amp I’ve crossed this week !
Changing the power supply could resolve the problem ?
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From what we as community members have tested so far, a new insulated groundless PSU seems to be solving a lot of the noise issues.
It’s worth trying as it’s a relatively inexpensive fix.
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For me, the problem has been solved with this (latest) update. Everything OK now. 
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Hello @Rom !
Try to isolate the problem.
In the first video it seems to be a USB related noise.
Also the noise described here in this topic is related to the MOD DUO not the Dwarf.
In the first video the USB adds a second noise, but it’s not the source of the F# at 375Hz, it’s only when I plug the dwarf into a guitar amp.
The noise described here (F# at 375Hz) for the Duo is exactly the same the I have, that’s why I post it here rather than adding another topic, sorry for that and thanks for your understanding.
For now I’m here :
- balanced cable doesn’t help (though I’m not sure the Line6 MM4 pedal I put after the Dwarf has balanced inputs)
- no noise when I plug the dwarf in my RME interface
- using this palmer isobox reduce largely the noise, even when I plug the USB, adding the Compensate Ground Loop feature is near perfect (but it’s not satisfying to use this to get one pedal guitar to work)
- waiting for another power supply I order Monday…
I’m in touch with Jon in PM to find the source of the problem
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Nice to know that you addressing the problem with the MOD Team already.
Have you tried to change the buffer size? On the DUO, setting it to 256 really helped. Then the software fix seems to have solved or minimized to a level that do not disturb me on the duo.
I´m waiting for my Dwarf and hopefully I´ll not have to deal with this problem again.
I´ll will try to look into it again to find out if the noise is REALLY gone or still there but it is insignificant.
Cheers
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Hi
This cheap power supply is resolving this issue :
(Still waiting for this one but no doubt about the result : alimentation K+ motherboard - bundle | Anasounds)
It’s okay on both situations :
- dwarf outputs → unbalanced jacks → two fender amps
- dwarf outputs → balanced jacks/xlr → two inputs of RME babyfacePro
Just the USB problem with my main computer bypassed by the bluetouth.
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This is very odd.
Wich are the differences between the DWARF power supply and this one?
No ground. And it’s less powerful, so if you plan to run multiple things in the control chain it may be too powerless.
Ok. Good to know.
Where you daisy chaining other devices using the DWARF power supply when you experienced the noise?
I mean… other devices also using the dwarf power supply as sorce of power?
I also believe the “square within the square” symbol indicates that it is double isolated/insulated. This seems to play a part in noise reduction according to the thread about the Mod dwarf.
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nope, not for now.
(I plan to use the Arduino Control Chain shield I’ve bought to build something with plenty of switches, but the time I can spend on it now goes on learning the multiple ways to use the dwarf !)
Getting back to the MOD DUO.
I connected the outputs of the DUO to my interface with balanced TRS cables.
- Empty pedalboard (no plugins) with inputs connected directly to the outputs.
- No bluetooth dongle, control chain nor USB cable were connected to t
- Both inputs and outputs at 100%
- Nothing connected connected to the inputs
- Interface input gain set at about 2 o´clock. For reference in a scale of 1 > 10 it´s about 5,5 to 6
Here is the images of the analises… They are virtually the same but channel one picks up more electrical noise interference than channel 2.
The bumps on the low end are at 120Hz and 240hz.
No noise can be perceived at normal input levels and the pitched noise (around F#) is not present in this scenario.
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THIS!!! solved the noise issue on my MOD Duo X and my MOD Dwarf! Thank you! (btw there is also an international site:Dehner Elektronik ATS 036T-A120 Bench PSU (fixed voltage) 12 V/DC 3 A 36 W Regulated | Conrad.com)
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Thanks for posting that, @rogeriocouto.
These resemble harmonics of the ground loop hum, if you are in a country/zone with 60Hz current. The fact that the 240 one has about half the amplitude of the 120 is very telling in that direction.
Of course we’re missing the actual 60Hz here, so unless there’s some filtering happening in any of the the PS units of your system or inside your interface, it should be present somewhere. Some audio components have a filter acting right at 50 or 60Hz to muffle ground hum.
Also, at least in theory, these harmonics you are detecting might be power grid hum due to grounding issues elsewhere in your building. Older buildings here in Europe have that all the time: you can have the nicest and cleanest electrical wiring in your apartment but the building as a whole has a shitty ground and that thrashes your AC power.
I’ve mentioned that elsewhere, but again: 100% gain at any stage is absolutely guaranteed to generate noise even with the super-ultra-mega highest quality amp money can buy. If you have a nice 120dB signal-to-noise ratio and pump the volume to maximum (let’s say it’s +60dB), then you will raise the noise floor to -60 at least (in theory). Your 120Hz buzz seems to be at that level.
This could instead mean you have a less efficient shielding or slightly defective capacitors on that preamp, more than the other. Only MOD can analyse and tell you that, though.
If you are connected to an audio interface and/or computer that’s plugged to the power source, than you can potentially get a ground loop. To run a spectrum analyser the way you did without any chance of getting power grid hum, you would need to use the MOD > interface power fed by the computer > computer fed by a battery (laptop preferably). That way, you have only one possible path to ground and would not have a loop.
(Of course, you can get EM and RF interference even in that case. But frequencies would likely differ.)
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Thanks @QuestionMarc !
I´ve set the inputs at 100% for test purposes only. As i said no noise can be perceived at normal levels and I have my inputs always at 0%.
About the channel 1 picking electrical interference, this was reported before but one needs to crank up the input to be able to hear it with the latest MOD software, at least with my setup.
Regarding noises I consider my MOD DUO free of problems.
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