Digital Noise Issues

I just got my Percussa SSP today and am having some bad digital noise issues. I saw another thread where others were dealing with the same thing but it was from a couple of years ago and now it’s closed so starting a new one to see if anyone has had luck since then solving this issue. I’ve tried a few different things so far with no success. I tried using only the SSP by itself in a synthrotek skiff with a bus board rated for +12v - 2A and in my 126hp MDLR case, with this power supply

mean well gst120a20-pm1

I tried running audio through other euro mixers and also just straight into my external mixer with the same results. Also i noticed the sound quality starts to degrade and distort significantly over time when the module is left playing for a few minutes. I tried only with a couple of the presets with little to no tweaking of any parameters and the same things happened on them every time. When i play the SINE test signal the digital noise is lowered slightly but still there. I have a new case on the way where I’m planning to rack the percussa but it won’t be here for a few weeks so I’ll have to wait to test it. Any suggestions for solutions I could try until then?

This is the thread i mentioned where i saw others dealing with digital noise

Optimizing case for Low Noise

Hi. I was looking for a thread about this also, so I’ll post here… I’m not sure it’s the same thing, but do you get noise when there are oscilloscopes and other waveform graphics being drawn on the screen? I have noticed this, and it goes away if I, for instance, press G to go back to the preset screen that has no moving graphics.

I have gone the 4ms Pod route, so my Percussa has its own case and power supply.

Edit: Basically I’m thinking the drawing of these graphics bleeds noise into the output somehow. Steps to reproduce:

  • Go to eg. factory preset “001. granular”
  • Press N, select GRA module and press P
  • (Choose a clean sound with no crackles, eg. Todd Barton’s excellent Shakuhachi Morphagene reel)
  • Experience crackles
  • Press G
  • Crackles go away, nice clean sound
  • Press P
  • Crackles come back

Yes i noticed this as well. Any screen with moving graphics seems to increase the noise level and actually sometimes scrolling with the encoders causes little noise artifacts too in my case

Welcome to the forum, snoom_leo.

I’ll verify the problem on my system and post here.

I just tested this and I can’t duplicate it. As usual, I suspect either a power or ground related issue; probably both, given the nature of Eurorack.

I experience no change in observable noise floor regardless of what is going on with the screen. I followed @littlebear 's procedure (without Todd’s sample set) and found no difference with the samples loaded on my system.

I’m using the top-of-the-line Intellijel power supply and buss boards.

Yikes, I guess that means I have power issues too :weary: Thanks for testing @Kent.

Anyone else experiencing this with a 4ms Pod and the brick that comes with it?

Sorry to hear it. Can you link us to the exact 4ms case and specs on the power supply?

@littlebear , do you have an external (Mackie, Soundcraft, other) mixer to go directly from SSP to the mixer and then headphones?
I’d like to test the shortest possible path. I used a long path and couldn’t reproduce the issue.

My SSP is in a 4ms Pod64x, using power 4ms supplies worth it.

I’ve not noticed any noise.

Previously I had the SSP in other cases and sometime had some digital noise - but it never was affected by moving encoders or anything going on with the screen.

That said, I’m with @Kent, sounds like a power related issue - perhaps when the screen is very active it’s pulling slightly power ( from cpu or gpu usage)

Like @thetechnobear, I’m using the 4ms Pod 60 Powered, which presumably uses the same power supply but not sure…

The brick I have does look pretty cheesy: RoHS SR-45W 100-240V~ 1.6A -> 15V - 3A

With a stout and clean power brick, that case should be fine. It claims to have enough overhead for an SSP.

Noise is almost always a system level issue or power supply design issue in situations like this.
This is why I ask if there is a standalone mixer available. Eurorack is a pretty noisy and cost-cutting environment.

Hi Kent, sorry I didn’t answer the mixer question: I’ve actually been mainly using the SSP on its own in the pod, with headphones plugged into the first two outputs (I have some headphones with a volume control on them.) So that’s the shortest path I can think of! (That, and USB audio into the Mac, where I have a DAC and other headphones plugged in.)

The crackles still happen with this minimal setup. Additionally, there are smaller crackles when navigating between modules on the Network screen to perform the steps above. So redrawing graphics in general seems to be the issue?

(Additionally additionally, sometimes the Granular module crashes the SSP when attempting to load the shakuhachi sample for the steps above, making me have to reboot, but not sure if that’s related.)

Just to be pedantic in checking:

• That headphones into the SSP sound great! Super direct.
• The USB cable is disconnected though, right? Just power cable to SSP’s case, and then the headphones?

This narrows things down hugely.

Out of curiosity, which headphones, what is the impedance, and how much gain are you applying to them?

yeah, mine looks to be the similar psu

nothing fancy… I’d assume its the 4ms bus board that does things like filtering.

Id try with nothing else connected - no usb, no patch cables , see if the noise goes.

my experience with noise on the SSP has always been related to other modules
either :

a) patching cables
plugging into a particular module or module on a particular bus would introduce some switching noise - it seem to be worst with mixer modules (likely due to opamps)

b) noise on the bus
having the SSP on the same bus as some digital modules would bring across noise to the SSP.

note: this noise was never crackling, rather digital switching noise - so pretty constant, and pretty quiet - really noticable when you turned up the gain.

I did alot of chasing of this issue around … using different racks and bus boards (including the Genus LIBB bux board)

I learnt a few general things…

even forgetting the SSP for a sec…
Eurorack is a noisy environment - ribbon cables, patch cables are basically are just antenna - things like ground loops are pretty common - digital modules and things like USB really excacerbate these issues.

e.g one confusion I had, is whilst testing the ssp noise issue - is I hadnt realise I had other digital modules that woudl introduce noise - in certain situations/configurations - so sometimes moving the SSP away from those modules would ‘solve’ the problem … until I made certain patch connections which seemed to ‘pollute’ the ground, and so get noise back on the SSP.

if you look at the muffwiggler forum, you’ll find someone having issues with every (more powerful) digital module … Instruo, Qubit, Squarp… all of them , yet others will be absolutely fine - its all put down to cetain modules/rack/power units… so unfortunately, this is pretty common even outside of the SSP :frowning:

the other thing Id be a bit careful of is assigning noise issues when using things like GRA or patches using alot of CPU.
its really easy to make GRA introduce ‘audio glitches’, just due to the nature of its synthesis.
similarly, perhaps CPU (overload) issues might only surface when graphics are being drawn, as this is taking CPU resources. ( though I believe the drawing is all done on a core that is not used for DSP)

I don’t know… but Id be pretty suspicous if you are only hearing noise when using one particular patch, that sounds more like a patch issue/cpu audio issue.
( I would not 100% trust the cpu meter either :wink: )

however, the reality is… I don’t know, as I dont have the issues you describe.
Im surprised an unconnected SSP would have issues - its certainly not been my experience.

btw: one small note…
the Pod64x is quite a bit deeper than the Pod60. also I leave the extra 4hp completely open, to allow air flow. honestly, when I had my SSP in my other racks, I got pretty concerned at how warm it was getting… even though I ensured it had adequate ventilation.

this is why I went with the Pod64x, the SSP now remains nice and cool, even when its been on for many hours (not unusual in a dev session !) which makes me feel much more confident.
that said… I see many have the SSP in racks surrounded by other modules without issue.

I have had mine powered from Rolands 500 series case and 4ms Row power and both I have never experienced issues, The only issue I have is I use windows, not mac.

Though I’m not sure it’s the same trouble, when I was using software ver 18102020, I had noise issue.

And I update to the latest software, noise issue was gone.

interestingly, I’ve recently run into a noise issue with the SSP - still trying to trace why… but it’s there, getting more intense the more complex an SSP patch happens to be. If I double or quad the sample rate, the noise jumps up in frequency relative to the clock. It’s not crazy loud - probably sitting around -75… but it’s enough to notice with quiet or more dynamic material.

This is surprising as im running Acopian linear supplies, LIBB bus boards and very thick wire with a doubled up common.

I’ll report back when I figure it out.

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It’s hard to know if we’re experiencing multiple different issues, or there is the same root cause. Thanks for everyone’s suggestions.

For me personally, my steps to reproduce posted above still stand - but I’ve narrowed it down to just patches with the GRA module included… and even then, just the more CPU-intensive ones. Not sure if other CPU intensive patches would do it also, guess I’ll have to give 12 Rngs a go or something :slight_smile: (if anyone has quick ways of producing large CPU load, I’ll try it.)

@Kent this is with just the SSP in the 4ms pod with brick and the headphones plugged into the first two outputs - nothing else attached. The headphones are a Sennheiser GameOne headset, nominal impedance 50ohms. It happens just the same in other configurations, though, and the fact that the crackles go away when you go back to the Global screen make me highly doubt it’s the headphones…

Edit: I should add that I feel blessed - with this setup, I’m not having any of the more general noise issues and in fact everything else sounds SUPER HI FI :sunglasses:

When I first received my SSP I put it in my intellijel 7u 104 hp case and was greeted with the worst digital noise I had ever heard.

I have, however, since rectified this problem to the point where the noise is minimal at best and I have to really crank the level to hear it now. Is it as good as when I was using all analog modules with a Pittsburgh modular power supply? No, but it’s now nearly unnoticeable and is easily filtered out with some additional processing.

What follows are the steps I took to fix this problem and the effect on noise reduction each step had as perceived by the ear. (if I had thought about this more I would have measured actual dB from one change to the next) it should be noted that I’m using the Inellijell 1u “Outs” module for my direct to headphones output. As many others have said a lot of the digital noise can be cut down just by using an external mixer, but I’m stubborn and I wanted this to work in a self-contained unit.

  1. Move SSP as far away from output module as possible in the case very small but noticeable decrease

  2. Plug SSP as close to first power plug in-series as possible this took a lot of trial and error as I didn’t have a multimeter handy, very small but noticeable decrease

  3. move other digital modules as far away from SSP in the case as possible while this didn’t decrease the noise from the SSP, it did decrease the noise effect the SSP had on adjacent modules.

That’s as far as I got with just rearranging my case, moved on to more drastic actions:

  1. Routed all cables in the case as far away from the back of the SSP as possible I had a noise issue with my ER-301 till I did this, so I figured I’d try it with the SSP. This required a lot of different ribbon cables and was a pain. A giant pain. which is why if you’re a sadist and are attempting this list in order, I recommend doing step 5 first. This did have a noticeable effect though! noise went down nearly 1/4th after completing this step.

  2. replaced all cables in my rack with these from modular addict far as I can tell these are the same cables @bert uses. Though he wouldn’t confirm for me over email. instantly noticeable noise decrease, about 1/4th

  3. pièce de résistance; purchased aluminum tape and wrapped the SSP’s and the output module’s ribbon cable completely. Insulated with electrical tape Gotta be really, really careful with this, a bunch of loose aluminum around the back of your modules is a recipe for disaster. make sure it’s very clean, and insulate it well. the ribbon cables are stiff after this process so doing step 4. again was a nightmare I do not wish to repeat. however: biggest noise reduction by far! out’s module has to be turned to nearly 3’oclock before noise can be heard

This is where I left it, I’m happy with this level of noise reduction. I did more which reduced the noise further, but since I never turn the level up on Out’s above noon I didn’t deem it necessary. I’ll include the additional steps in case someone wants to take it even further. or the previous 6 steps didn’t work for them.

  1. negative offset At least for me anyway, the noise is constant, and when viewed on a scope is a purely positive voltage. I could take an unused output from the SSP, mult it, and run it through an attenuverter for a perfect negative. completely got rid of the noise. A totally clean signal achieved.

  2. use an out-of-case mixer people said it worked, I tried it. It worked. Prior to doing any of the other steps, it cut down on noise issues by half, after these steps completely removed the noise

  3. change power outlets Noticed a distinct change in the noise level depending on the outlet used for my power brick. With the best effect in my garage. Obviously not doable for me, but could work for you!

And that’s it! I know everyone’s noise issue and setup are a little different, but hopefully, this helps someone.


Thanks for this info. I also have my SSP in an intellijel 7u case and the outputs either go through a 1u intellijel headphones out in the same case or a befaco hexmix in another intellijel 7u case. It’s really noisy it’s almost like I can hear every process the ssp is doing internally!

I’ll try swapping the power cables for those recommended, routing them away from the back of the SSP and changing up which power socket the SSP goes into for a start

Edit @DSPaddict I’m guessing the post you wrote was referencing the ways you minimalists noise on the 7u intellijel case? If so could you please tell me which connector on the 7u intellijel case is the first in series? I plugged my SSP into the one closest to the left I think of what looked like where the power came into the connectors. I wouldn’t know how to test the power connections for lowest noise as I’m a complete amateur at this?