MUM M8 weird noise bleeding

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raccoonboy
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MUM M8 weird noise bleeding

Post by raccoonboy » Tue Jun 30, 2020 1:04 pm

I've heard other folk having this issue before. Is there any way to stop this happening? I think it's down to the PSU (intellijel performance 7u case).

Basically I was getting a minimal amount of noise as far as I recall that was definitely bearable but now that I've my final module 'noise tools 1u' by intellijel, whatever pulse rate I have I can hear this bleeding into the MUM M8 even though the noise tools isn't plugged into anything. I think it's because they both have a digital clock that they're interfering with eachother.

I'll get a whiney high pitched sounds at certain filter cutoff points (especially when boosting my lineout signal over 0dB).

Otherwise from my quick use the filter sounds pretty damn good.

Anybody got any ideas?

thanks

Sookilala
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Re: MUM M8 weird noise bleeding

Post by Sookilala » Tue Jun 30, 2020 7:45 pm

there is inherent noise, Its a property of the design of the filter

im guessing its something to do with this, it seems most likely

you will need to calibrate to remove the noise

From the manual

Calibration
There are two trimmers on the rear on the module which can be used to adjust the minimum cut off frequency for the filter. Because of the filters architecture, too low a cut off frequency will introduce high pitched noise into the audio signal (from the filters controlling clock signal).
The top trimmer (marked ‘FREQ OFF ADJ’ ) sets the ‘base’ cut off frequency - i.e the cut off will effect the main control knob on front of module turned full counter clockwise and no CV inputs patched. The lower trimmer (marked ‘FREQ MIN ADJ’) hard limits the minimum frequency of the filter (from knob or cv input). The trimmers are adjusted with a small flat head screwdriver.
To calibrate;
1. Turn filter knob full counter clock wise (CCW), Resonance knob full CW - so filter is in self oscillation.
2. Turn top ‘FREQ OFF ADJ’ trimmer full CCW. Turn lower ‘FREQ MIN ADJ’ trimmer full CW. You should now hear no resonance but the clock noise.
3. Turn ‘FREQ OFF ADJ’ CW until you can hear just resonance and so that the clock noise has subsided (approx 1/4 to 1/3 of a turn)
4. Turn ‘FREQ MIN ADJ’ CCW to just before the point it affects the resonance frequency.
Note the module is pre calibrated at the factory but by all means adjust to taste!


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raccoonboy
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Re: MUM M8 weird noise bleeding

Post by raccoonboy » Wed Jul 01, 2020 2:06 am

Sookilala wrote:
Tue Jun 30, 2020 7:45 pm
there is inherent noise, Its a property of the design of the filter

Sookilala wrote:
Tue Jun 30, 2020 7:45 pm
Because of the filters architecture, too low a cut off frequency will introduce high pitched noise into the audio signal (from the filters controlling clock signal).


Thanks but the noise is when the filter is very open. As I said. It's not it's own clock bleed it's the clock of another module I'm hearing which is kinda bizzare

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raccoonboy
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Re: MUM M8 weird noise bleeding

Post by raccoonboy » Wed Jul 01, 2020 2:45 am

Okay. Looks like I'm hearing interference even without the M8. If I crank the volume I can still hear the noise tools clock. It's just a hiss though rather than a squeel. Going to try repositioning the unit otherwise I'll get in touch with intellijel as it seems to be a problem with the case. Might need a different sample&hold solution

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hautlle
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Re: MUM M8 weird noise bleeding

Post by hautlle » Wed Jul 01, 2020 2:54 am

Maybe the Noise Tools is the issue or the filter is very sensitive? Here's another person experiencing the same thing 2 years ago but with Cold Mac:

https://llllllll.co/t/troubleshooting-n ... m/11787/22
Olivier
Apr '18
This seems like a good spot to bring up something I encountered while installing/testing modules in my brand new Intellijel 7u case last night.

One of the modules I installed is the Intellijel 1u Noise Tools. Curiously, noise from that module seems to bleed on through to the right outputs of the Cold Mac only, audibly following the rate of the clock or the random pulse depending on what’s selected. The path is simply any output from Cold Mac (with no inputs) to the Intellijel i/o tile and then from the balanced 1/4" outputs on the back to my mixer.

If I take an output from the Linix instead of Cold Mac to the i/o tile, that bleed from the Noise Tools seems to disappear. Any ideas around further debugging what seems to be a bleed problem between two specific modules?

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raccoonboy
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Re: MUM M8 weird noise bleeding

Post by raccoonboy » Wed Jul 01, 2020 6:09 am

hautlle wrote:
Wed Jul 01, 2020 2:54 am
Maybe the Noise Tools is the issue or the filter is very sensitive? Here's another person experiencing the same thing 2 years ago but with Cold Mac:

https://llllllll.co/t/troubleshooting-n ... m/11787/22
Olivier
Apr '18
This seems like a good spot to bring up something I encountered while installing/testing modules in my brand new Intellijel 7u case last night.

One of the modules I installed is the Intellijel 1u Noise Tools. Curiously, noise from that module seems to bleed on through to the right outputs of the Cold Mac only, audibly following the rate of the clock or the random pulse depending on what’s selected. The path is simply any output from Cold Mac (with no inputs) to the Intellijel i/o tile and then from the balanced 1/4" outputs on the back to my mixer.

If I take an output from the Linix instead of Cold Mac to the i/o tile, that bleed from the Noise Tools seems to disappear. Any ideas around further debugging what seems to be a bleed problem between two specific modules?
It seems like the there are multiple things going on here. I think the performance case's power is the main issue, but possibly also the noisetools (I haven't tried it in another rack yet) and definetly also the M8. It's just a coincedence that these were the last two modules I installed into my rack.

-Noisetools 1u bleeds into the output as white noise (even if completely unpatched). I know this because the white noise varies slightly in frequency comparason to its clock speed. It seems to be worse on track, rather than sample and if I turn the clock speed right down and slew fully clockwise (or send a DC signal to the sample in) then the noise is at least unvarying and quite subtle, you only hear it at loud volumes. I can probably deal with this long term, but it's still quite annoying that I must do this. If I'm using the sample and hold then at least the extra noise will have the same timing and therefore less noticeable. Actually when I'm home I ought to test it with a different trigger input as this would stop the internal clock being used.

-Mum M8 turns this strange clock bleed (from the Noisetools) into high pitched squeels at certain (high) frequencies when the filter is mostly open. Removing the Noisetools the frequency squeels are still there but are constant (as opposed to varying at noise tool's clock speed).

-Mum M8 on a different mini doepfer rack. No squeels whatsoever, however it's quite noisey. I kind of wanted to use this thing as my master filter, but introduces a lot of white noise too.

I'll have a read of that troubleshooting link you sent, cheers

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raccoonboy
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Re: MUM M8 weird noise bleeding

Post by raccoonboy » Wed Jul 01, 2020 6:10 am

Okay I've read a bit of that now.. Looks like other folk have had the same issue with Noise Tools 1u. But it looks like the 4ms power row might be an issue. When I get home later today I'll try plugging in the Noise Tools 1u and the possibly the Line Output into the main bus board see if this helps. I'll keep trying and see what I can do.

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raccoonboy
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Re: MUM M8 weird noise bleeding

Post by raccoonboy » Wed Jul 01, 2020 5:41 pm

hautlle wrote:
Wed Jul 01, 2020 2:54 am
Maybe the Noise Tools is the issue or the filter is very sensitive? Here's another person experiencing the same thing 2 years ago but with Cold Mac:

https://llllllll.co/t/troubleshooting-n ... m/11787/22
Olivier
Apr '18
This seems like a good spot to bring up something I encountered while installing/testing modules in my brand new Intellijel 7u case last night.

One of the modules I installed is the Intellijel 1u Noise Tools. Curiously, noise from that module seems to bleed on through to the right outputs of the Cold Mac only, audibly following the rate of the clock or the random pulse depending on what’s selected. The path is simply any output from Cold Mac (with no inputs) to the Intellijel i/o tile and then from the balanced 1/4" outputs on the back to my mixer.

If I take an output from the Linix instead of Cold Mac to the i/o tile, that bleed from the Noise Tools seems to disappear. Any ideas around further debugging what seems to be a bleed problem between two specific modules?
As suspected, plugging a patch cable into the trigger input of the noisetools stops the noisebleed of that module. So I can leave it patched when not in use. Moving it off the 4ms power strip helped a little too.

I'm thinking of investing in a few NKPs and see how they work

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