Dealing with computer hum

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WilliamJones

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I bought a new computer system to use with a Allen&Heath sound board. I am using onboard audio from line out to a 1/4" jack on the sound board. The problem is that there is a humming sound (like a motor running) coming from the sound board. I may have gone too cheap with the motherboard, but I am stuck with it now. Also, all the expansion slots are filled, so cannot just add a sound card. I tried a $10 Mpow ground loop isolator, but that did nothing. Someone suggested a Samson MCD2. Does anybody have a different suggestion? Does the Samson actually work in elininating the hum?
EDIT: Forgot to mention that there is a $300 add-on card for my sound board that adds USB. That enables us to have USB out of the computer to the newly added USB card for audio in to the sound board.
I think I am in over my head and not sure which way to go from here. If the Samson will work, that costs just over $100 and will be happy to try that first.
 
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Its not clear what you are using and how you are using it.
You are using onboard audio analogue out that has a hum.
All ok up to here.

You have a $300 add on card for the sound board that does USB to a newly added USB card.
Deciphering this I think you mean:
"I have a $300 USB sound card or external DAC"
Is that correct?

If so what difference did it make to the hum?
If that is not correct, please explain.

What sound system are you using?
Have you tried headphones to see if the hum remains?

Can you describe the hum.
Does it change when the computer is processing?
Is it low or high pitch?
Does it vary in loudness?
 
Sorry if this was not clear. I have a Win10 computer that has onboard sound as part of the motherboard. When this onboard sound is connected to the A&H MixWizard there is a loud hum when playing anything coming from the computer. I would like to fix this hum and there are three things that others have suggested. I am not sure which one, if any, will eliminate the hum. Here is a list of the suggestions (of which I tried #1) :
1) $10 inline filter. I tried this, but it did nothing.
2) $100 Samson MCD2 (link in my original post) . This is a metal box that acts as a filter. It is placed between the computer and the MixWizard sound board.
3) $300 add on card for the MixWizard. The MixWizard website shows this as a daughter board type addition for the MixWizard that requires a certified tech to install.
Anybody have any experience with any of these?
 
Try some ferrite clamps? I have them on the mains cable and the power cables inside my PC (The 24 pin/8 pin CPU and GPU).

They don't cost much.

I even run my PC and monitor through a couple of these from my sick puppy hi-fi days...

https://www.russandrews.com/yello-power/
 
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I'd just get an external dac, something with optical.
Usb could work too or it might still have ground issues.
 
Really just need to know what you're actually doing. What specific parts are you using, what specific ports are you using, and what specific settings are you using. Hard to narrow down solutions without knowing the work intended to be done.

WilliamJones said:
Someone suggested a Samson MCD2.
Click to expand...

This appears to convert two unbalanced signals into a balanced signal. This would be useful if you have a clean unbalanced output that then needed a long run through an electromagnetically noisy environment, but doesn't mean that a hum that is in an unbalanced signal would be mitigated.

WilliamJones said:
EDIT: Forgot to mention that there is a $300 add-on card for my sound board that adds USB. That enables us to have USB out of the computer to the newly added USB card for audio in to the sound board.
Click to expand...

This is probably the best solution. It's expensive, given that it's literally just a USB DAC, but it's also guaranteed to work.

xmadror said:
I'd just get an external dac, something with optical.
Usb could work too or it might still have ground issues.
Click to expand...

If the OP could get an optical DAC that has balanced outputs, that would be ideal. I use a Topping DX7s ($499 with 10% off coupon for $449) for this, that also has a decent balanced headphone amplifier and thus is a bit overkill. Topping does have their D70 DAC that lacks the headphone amp and is unfortunately the same price as the DX7s, likely because it is newer.

However, there are some options that pop up with a quick search:
  • Audio interface-style solutions:
    • For cheap and simple, but also just USB, Peavey has their USB Audio/Recording Interface for US$54 shipped that just does straight USB to XLR pair- so long as no noise due to interference is affecting the USB signal or the internals, you should get relatively clean output
    • For US$279, you can get a full-blown rackmount interface from Behringer in their Ultracurve Pro DEQ2496 - if you're going to spend the money, this is would be my choice
    • For a bit less than the Behringer and a little smaller, you can get Focusrite's Scarlett 4i4 3rd Gen for US$230- this is USB only, but has four balanced outputs that could provide more channels for your mixing board, and also comes with software licenses that may be useful
    • An interesting option would be to use Focusrite's outgoing Scarlet 6i6 2nd Gen also at US$230 which has the same functionality as the 4i4, but adds S/PDIF coaxial connections, which you can convert to optical using a simple powered inline converter like this generic bi-directional converter for US$17 shipped
  • 'HiFi' solutions:
    • SMSL has their very high-end M300 DAC for US$240 that has fewer features beyond the necessary optical input and balanced XLR output pair, and like the Focusrite parts only comes in a variation of red
    • SMSL also has a nice 'HiFi Decoder' in their SU-8 for US$250 which has the same basic connectivity as the M300, but in a shallower and wider profile and it comes in silver
    • Cambridge Audio has a more 'hifi' option with their Azur DacMagic Plus at US$350 which does have two optical inputs as well as a high-end headphone jack
Outside of these, you could try any cheap 'external soundcard' which is what a USB DAC is (and all of the above are). You'd be using USB and unbalanced connectors, but if the USB output is clean and the unbalanced signal doesn't pick up interference, it would likely work well enough. Everything I've listed above other than the Peavey is in some part an increase in functionality and in some part an increase in audio quality, and that list is far from exhaustive as it was pulled from only Amazon using their notoriously clunky search tool.

Also, I'm responding in detail because I also wanted to see what options were available for optical DACs with stereo XLR outputs beyond the Topping DX7s that I personally use.
 
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IdiotInCharge said:
If the OP could get an optical DAC that has balanced outputs, that would be ideal.
Click to expand...

I doubt balanced vs unbalance matter much in this case for an optical dac.
Unless the OP is using balanced gear ? which I don't think is the case.
Something like a $99 schiit modi should take care of the noise and will also sound better!


IdiotInCharge said:
Also, I'm responding in detail because I also wanted to see what options were available for optical DACs with stereo XLR outputs beyond the Topping DX7s that I personally use.
Click to expand...

https://www.schiit.com/products/gungnir
https://www.schiit.com/products/yggdrasil

Also this one is a heaphone amp with optional dac and can also be used as a preamp.
https://www.schiit.com/products/jotunheim

No experience with any of these but I love my Bifrost (akm4490) which is a step down from the gungnir.
 
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xmadror said:
I don't think balanced vs unbalance matter much in this case for an optical dac.
Unless the OP is using balanced gear ? which I dont think is the case.
Something like a $99 schiit modi should take care of the noise and will also sound better!
Click to expand...

The OP is certainly using balanced equipment- it's a mixing board, though they have not yet listed the specific model. And the reason for looking at the combination of an optical DAC with balanced output is to simultaneously break potential USB ground loops as well as to strongly mitigate any potential interference that an unbalanced cable pair could pick up between the DAC and the mixing board.

As I stated above, a cheap USB DAC might be all the OP needs to get rid of the hum; I provided more options mostly out of personal curiosity. Also, given the 'simple balanced optical DAC' premise, Schiit is mostly out of the running due to cost as that's just not a market that they have chosen to service, for whatever reason.

xmadror said:
https://www.schiit.com/products/gungnir
Click to expand...

...because that's US$850 and provides less functionality than every option I linked aside from the cheap Peavey

xmadror said:
https://www.schiit.com/products/yggdrasil
Click to expand...

...and that's US$2400 and again provides less functionality

xmadror said:
https://www.schiit.com/products/jotunheim
Click to expand...

...and that's US$500 while providing the same functionality to the OP as the US$54 Peavey, i.e., no optical input.


I can't say that I'm a fan of Schiit, but I'm also not a detractor- I just don't find value in most of their products, and as it stands, their only product that fits the premise is US$850 vs. < US$300 audio interfaces and hifi DACs that add functionality at a significant cost savings.

And let's be clear: a highly-rated optical to unbalanced DAC is available from FiiO with their D3 DAC for US$20- and will likely get the job done.
 
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I didn't realized that the OP was using a mixing board so you are most likely right in assuming it is balanced.

To be clear I wasn't suggesting those expensive dac to fix the OP's problem but more because of that quote in (in my previous post) from IdiotInCharge.

Schiit is not for everyone, I get that. For some reason they seem to be popular with people who have vintage gear (which is my case).
A few years ago I upgraded the dac board inside my bifrost to the akm4490 from the akm4399 and it was worth the $100! I'm not aware of any other Dac that you can upgrade for similar cost.
Feature wise, I don't expect more then optical/coax/usb in and unbalance out. Not sure why you'd need anything else on a dac (aside from the balanced out if you have other balanced gear)

I think you can also find a few balanced dac on drops.com (massdrop) not sure on price but they wont have more functionality then a schiit dac.
 
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xmadror said:
I didn't realized that the OP was using a mixing board so you are most likely right in assuming it is balanced.
Click to expand...

There are good reasons to use balanced equipment; in my case, I have a 10" studio sub with balanced stereo XLR passthrough for input, and from there a pair of balanced studio monitors. Coming from the balanced stereo XLR outputs on the DX7s, I get a balanced signal from DAC to speaker amps. Even have a balanced pre-amp for volume with a switcher that lets me put another headphone amp (with a tube) in the chain.

This eliminates interference, something I've dealt with in the past. Overkill for sure, but aside from the DX7s, not terribly expensive for the assurance.

xmadror said:
I think you can also find a few balanced dac on drops.com (massdrop) not sure on price but they wont have more functionality then a schiit dac.
Click to expand...

That is where I picked up my Topping DX7s- for significantly less than the sale price on Amazon- but in nearly all cases there's a significant wait time attached and there are functional equivalents available from Amazon with next-day shipping.

xmadror said:
Schiit is not for everyone, I get that. For some reason they seem to be popular with people who have vintage gear (which is my case).
A few years ago I upgraded the dac board inside my bifrost to the akm4490 from the akm4399 and it was worth the $100! I'm not aware of any other Dac that you can upgrade for similar cost.
Click to expand...

You can get quite decent headphone DACs for US$100 ;).

xmadror said:
Feature wise, I don't expect more then optical/coax/usb in and unbalance out. Not sure why you'd need anything else on a dac (aside from the balanced out if you have other balanced gear)
Click to expand...

It's the combination of an optical DAC and balanced stereo outputs that's rough. I wasn't able to find anything for less than US$240 on Amazon, even though it's a pretty straightforward setup electrically speaking and could be done well for far less in my opinion.
 
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