Go Back   Cockos Incorporated Forums > REAPER Forums > REAPER General Discussion Forum

Reply
 
Thread Tools Display Modes
Old 01-14-2017, 03:48 PM   #1
foxAsteria
Human being with feelings
 
foxAsteria's Avatar
 
Join Date: Dec 2009
Location: Oblivion
Posts: 10,255
Default Optical Mixer to Get Rid of Motherboard Noise?

The noise interference generated by my PC, amplified by my mixer and outputted by my monitors is becoming intolerable. My PCIe soundcard and the mobo sound both have S/PDIF optical outs, so my question is:

Is there such a thing as a small optical S/PDIF input mixer?
(preferably <$30) It also needs to have a DAC, but the quality doesn't need to be stellar.

In my quest to rid myself of this cacophony I've determined that optical signals don't suffer this noise problem, but the closest I've found is a 2 input switch on Amazon. I need 2-3 optical signals to be simultaneous, with independent volume control. Maybe "optical mixer" isn't the right term, but you get the idea...

Alternatively, I'd be willing spend around $100-200 or so to simply replace my Xenyx1002FX mixer with something that can do this.
__________________
foxyyymusic

Last edited by foxAsteria; 01-14-2017 at 04:02 PM.
foxAsteria is offline   Reply With Quote
Old 01-14-2017, 04:03 PM   #2
SoulOne82
Human being with feelings
 
SoulOne82's Avatar
 
Join Date: Sep 2008
Location: Illville - Germany
Posts: 972
Default

Quote:
Originally Posted by foxAsteria View Post
The noise interference generated by my PC, amplified by my mixer and outputted by my monitors is becoming intolerable.
Is your wiring entirely balanced?
SoulOne82 is online now   Reply With Quote
Old 01-14-2017, 04:39 PM   #3
foxAsteria
Human being with feelings
 
foxAsteria's Avatar
 
Join Date: Dec 2009
Location: Oblivion
Posts: 10,255
Default

Quote:
Originally Posted by SoulOne82 View Post
Is your wiring entirely balanced?
No, but I don't imagine that would make a lick of difference though. Not that kinda noise.

Edit: OK I tried it and it does reduce the noise a bit. I just want it gone though. The noise is being added before the signal even hits the cables, as it's most affected by GPU activity.

For now I'm just routing the mobo sound digitally into my E-Mu card, as that seems to be far less noisy than outputting them both analog.
__________________
foxyyymusic

Last edited by foxAsteria; 01-14-2017 at 05:06 PM.
foxAsteria is offline   Reply With Quote
Old 01-14-2017, 06:42 PM   #4
drumphil
Human being with feelings
 
drumphil's Avatar
 
Join Date: Jun 2006
Location: Australia
Posts: 3,738
Default

Sounds like ground loop issues.

Do you have anything other than the mixer plugged into your amp? Does your amp have a three pin power plug? Or are you using powered monitors?

What happens if you only have the PCIe sound card connected to the mixer, connected to the speakers, with the on board sound not connected, and nothing else connected to any of it?

Quote:
The noise is being added before the signal even hits the cables, as it's most affected by GPU activity.
That conclusion is faulty, as ground loops will introduce such noise into a system. Now, some sound cards are just noisy, but usually they aren't, and these type of problems are almost always ground loop related. That's why SoulOne82 was asking about balanced wiring.

A properly balanced system should be largely immune to such noise, but depending on exactly what is causing the ground loop, unbalanced systems can be made to work too.


What I suspect is happening is that you have a computer with a three pin power plug, which means it has a ground pin. The power supply for the amps that run your speakers also have a three pin power plug with a ground pin. When they are both plugged in their ground is connected through the power wiring. Then you plug your audio cables in, which in an unbalanced connection has a signal and a ground. Now you have two different ground paths between the computer and the speakers. One in the audio cable, the other through the power cables. So, somewhere the loop needs to be broken. Your mixer only has a two prong wall plug, so it isn't the source of the problem, however a mixer with balanced outputs could solve the problem.

Balanced cables solve this problem by not using ground as part of the signal path. They have positive and negative phase, plus a shield, which is usually connected to ground in the chassis, but for audio purposes can be left disconnected at one end, so no ground link between bits of gear. Leaving the shield disconnected doesn't really make any different to noise rejection, as shielding does little at audio frequencies, and most of the noise rejection of the circuit is because it is balanced, not because it is shielded.

Now, in theory the loop could be broken by removing the ground pin from one of the power plugs. DO NOT DO THIS. Without the ground connected you have no protection if a fault occurs that makes the chassis of the equipment live. The ground is there so that if this happens, the current flows to ground through the power plug, and not through you when you touch the box.

So, there are two places you can break the loop. Between the PC and the mixer, or between the mixer and the speakers. If your mixer had balanced outputs you could break the loop there, but it doesn't. If you sound card had balanced outputs you could break the loop there, but it doesn't. edit: or does it?

So, what do you do?

Well, you could just get a mixer with balanced outputs. Or you could get a box that provides isolation between the pc and the mixer, or the mixer and the speakers.


But first, some basic testing. Leave the on board disconnected from the EMU. Plug some headphones directly into the EMU, with nothing else plugged into anything. Is the noise there? If not, then it being caused when you connect everything together, and isn't just being sucked into the sound card from the other components in the computer. If it is nice and quiet, then the problem is almost certainly a ground loop when everything is connected.

If the EMU sound card has balanced outputs, and you are using them, but you still get noise, try some modified XLR or TRS cables with the shield disconnected at one end. The shield being connected means there is still a ground path from your PC, through the mixer, to the speakers.

You have to be methodical to figure such problems out, with the minimum of things possible to test plugged in at any point in time, to allow to you accurately determine exactly which part in the link is causing the problem.

The best reference around for explaining these sorts of problems, and how to solve them. From the Rane Notes:


Sound System Interconnection:

http://www.rane.com/note110.html


Grounding and Shielding Audio Devices

http://www.rane.com/note151.html


Also, why do you want the on board sound running at the same time? Why not just use the EMU?

Last edited by drumphil; 01-14-2017 at 07:24 PM.
drumphil is online now   Reply With Quote
Old 01-14-2017, 07:40 PM   #5
foxAsteria
Human being with feelings
 
foxAsteria's Avatar
 
Join Date: Dec 2009
Location: Oblivion
Posts: 10,255
Default

Thanks, but it's definitely not ground loop. There is no hum. The noise happens when I move my mouse or I use graphic intensive apps, sometimes during hard drive activity. I've already looked into this quite intensively and the only solution I've come across is to use the optical outs and do the DAC outside of the PC.

I'd just like to know if such a device exists.

Quote:
Originally Posted by drumphil View Post
Also, why do you want the on board sound running at the same time? Why not just use the EMU?
Because I'm sick of trying to figure out why Reaper doesn't make sound when I left some app running in the background, which has taken over the device driver (usually a web browser). Even though it's happened so many times, my memory is shit and it still occasionally wastes much of my time.
__________________
foxyyymusic

Last edited by foxAsteria; 01-14-2017 at 07:46 PM.
foxAsteria is offline   Reply With Quote
Old 01-14-2017, 07:48 PM   #6
drumphil
Human being with feelings
 
drumphil's Avatar
 
Join Date: Jun 2006
Location: Australia
Posts: 3,738
Default

Quote:
Thanks, but it's definitely not ground loop. There is no hum.
Lol, ground loop doesn't always manifest as a hum. What happens when you just listen to the EMU through headphones plugged straight in to the EMU, not the mixer? Is the noise gone? If so, then the noise isn't being picked up by the card from inside the computer.

So, test that and get back to me.

The symptoms you are describing are exactly what I'd expect from a ground loop problem. If I plug my other computer into the same amp this one is connected to I get the exact same type of noise you are talking about. Disconnect the other computer, noise disappears! Either computer connected individually, no noise, both plugged in, noise every time.

Solving ground loops issues is something I got pretty good at since I began working in radio studios.

Another example of this type of ground loop problem. You know how sometimes when you plug headphones into the front panel headphone out on a case, and you can hear the type of noise you're talking about? Usually it has little to do with the on board sound, and is actually caused by the audio and USB ground being connected at the front panel, creating a ground loop. It's actually most often the fault of the case designer, rather than a weakness with on board sound!

Using an optical output could solve the problem, but most likely not for the reasons you think. There is no ground, or any electrical connection with an optical link, so the ground loop is broken. But depending on what you connect the optical cable to, that device will have a power supply, and analog electrical outputs, and you can end up with the same problem again, just with different bits of gear.

So, lets be certain of what the problem is first before deciding how to solve it. You're assuming the noise is being picked up inside the computer, and you don't know that yet.

Last edited by drumphil; 01-14-2017 at 08:03 PM.
drumphil is online now   Reply With Quote
Old 01-14-2017, 08:11 PM   #7
Bri1
Banned
 
Join Date: Dec 2016
Location: England
Posts: 2,432
Default

Quote:
Originally Posted by foxAsteria View Post
Thanks, but it's definitely not ground loop. There is no hum. The noise happens when I move my mouse or I use graphic intensive apps, sometimes during hard drive activity. I've already looked into this quite intensively and the only solution I've come across is to use the optical outs and do the DAC outside of the PC.

I'd just like to know if such a device exists.
This appears to be a case of usb loop.
There are isolators for usb,as well as isolators for dsp/voltage available.
Bri1 is offline   Reply With Quote
Old 01-14-2017, 08:12 PM   #8
Masonic
Human being with feelings
 
Join Date: Mar 2010
Posts: 190
Default

Quote:
Originally Posted by foxAsteria View Post
Thanks, but it's definitely not ground loop. There is no hum. The noise happens when I move my mouse or I use graphic intensive apps, sometimes during hard drive activity. I've already looked into this quite intensively and the only solution I've come across is to use the optical outs and do the DAC outside of the PC.
Yes, I know exactly what you're talking about. I have RME AIO and always can hear interferences when moving my mouse, or when hard drives are waking up. It is annoying as hell. Lynx Audio TWO is a lot better shielded but nothing beats an external AD/DA.
Masonic is offline   Reply With Quote
Old 01-14-2017, 08:14 PM   #9
drumphil
Human being with feelings
 
drumphil's Avatar
 
Join Date: Jun 2006
Location: Australia
Posts: 3,738
Default

Sigh, if USB was the only solution, then how on earth do internal sound cards function without problems? No noise with my Delta 1010lt, unless I actually have ground loop problems in the rest of the system that haven't been diagnosed.

A properly designed internal sound card can work just as well as an external unit.

I know appeals to authority don't mean much, but this is actually what I do all day as a computer/DAW/studio technician.
drumphil is online now   Reply With Quote
Old 01-14-2017, 08:17 PM   #10
foxAsteria
Human being with feelings
 
foxAsteria's Avatar
 
Join Date: Dec 2009
Location: Oblivion
Posts: 10,255
Default

There is no headphone out on the E-Mu. I'll try the things you suggest and see what I can come up with. I guess I don't understand ground loop as well as I thought, but I've I've always been under the impression that ground loop was not possible with all electronics plugged into the same outlet (through a power strip which reports proper grounding). The only element here without a 3rd prong on the plug is the mixer, but that's going through the strip as well.
__________________
foxyyymusic
foxAsteria is offline   Reply With Quote
Old 01-14-2017, 08:23 PM   #11
drumphil
Human being with feelings
 
drumphil's Avatar
 
Join Date: Jun 2006
Location: Australia
Posts: 3,738
Default

Quote:
Originally Posted by foxAsteria View Post
There is no headphone out on the E-Mu.
For a quick test, just plug the headphones directly into the line out. Which EMU card do you have? edit: or leave the speakers disconnected, and plug the headphones into the mixer. That shouldn't create a loop as the mixer only has a two prong power plug. If you have the 0404 then you really don't have a headphone compatible plug, so that may be the only way to check.

Quote:
I'll try the things you suggest and see what I can come up with. I guess I don't understand ground loop as well as I thought, but I've I've always been under the impression that ground loop was not possible with all electronics plugged into the same outlet (through a power strip which reports proper grounding).
The loop happens because there are two ground paths. One through the power strip, with the ground pins from the three prong plugs all connecting to each other. And the other through the ground on the audio connectors. So, two ground paths = loop.

Quote:
The only element here without a 3rd prong on the plug is the mixer, but that's going through the strip as well.
So, you have the ground from the computer and speakers connected together at the power strip, and the ground from the audio path connecting from the PC to the speakers through the mixer.

If the speakers didn't have a ground pin on their power plugs you probably wouldn't be having this problem.

Last edited by drumphil; 01-14-2017 at 08:29 PM.
drumphil is online now   Reply With Quote
Old 01-14-2017, 08:26 PM   #12
foxAsteria
Human being with feelings
 
foxAsteria's Avatar
 
Join Date: Dec 2009
Location: Oblivion
Posts: 10,255
Default

Yes I still hear the noise from headphones from either sound device. E-Mu 1212M. Here's a funny thing: when I monitor with phones thru the mixer, no noise. But as soon as I connect the powered monitors, noise, with balanced and unbalanced cables.
__________________
foxyyymusic
foxAsteria is offline   Reply With Quote
Old 01-14-2017, 08:31 PM   #13
drumphil
Human being with feelings
 
drumphil's Avatar
 
Join Date: Jun 2006
Location: Australia
Posts: 3,738
Default

Is that with EVERYTHING else disconnected?

Just had a look at your sound card. The plug the headphones into the card directly won't work because it has balanced outputs, so the valid test is what you just did listening through the mixer. That the noise goes away when you unplug the speakers points to a ground loop being the problem.

I'd try using balanced cables between the sound card and the mixer, with the shield disconnected so that the ground path is broken. No point worrying about the mixer to speaker link using balanced cables because your mixer doesn't have balanced outputs anyway, and only has balanced in on the first two channels.

You are plugging in to the balanced in's on the mixer (channels 1 and 2), and not the other channels?

Quote:
when I monitor with phones thru the mixer, no noise.
Well, that proves that the noise isn't being picked up by the card from inside the computer


edit: so, a simple test.

Plug balanced cables from the sound card to channels 1 and 2 on the mixer. Any noise on the headphones plugged in to the mixer? Then connect the speakers with unbalanced cables. Does the noise come back? If so, try using balanced cables with the shield disconnected at one end to connect the sound card to the mixer.

If you're plugging the output from the sound card into the unbalanced inputs on the mixer, a ground loop is certain.

Last edited by drumphil; 01-14-2017 at 08:45 PM.
drumphil is online now   Reply With Quote
Old 01-14-2017, 08:44 PM   #14
foxAsteria
Human being with feelings
 
foxAsteria's Avatar
 
Join Date: Dec 2009
Location: Oblivion
Posts: 10,255
Default

I'm getting so confused. Yes, I'm testing with only the minimal connections. I had already connected the E-Mu to the mixer on one of the stereo line ins (says balanced or unbalanced) with balanced TRS cables.

I'm just gonna take a moment to fully test this all from scratch.

But if I'm only hearing the noise through the monitors, you reckon it's just because the mixer doesn't have balanced outs? I guess I wouldn't mind replacing that cheap old thing...
__________________
foxyyymusic

Last edited by foxAsteria; 01-14-2017 at 08:53 PM.
foxAsteria is offline   Reply With Quote
Old 01-14-2017, 08:49 PM   #15
drumphil
Human being with feelings
 
drumphil's Avatar
 
Join Date: Jun 2006
Location: Australia
Posts: 3,738
Default

OK, lets make this simple. Just start with balanced cables from the sound card going to ch 1 and ch 2. Check the headphones for noise. Then plug unbalanced cables from the mixer to the monitors. Check for noise again.

The mixer might say "balanced or unbalanced" on the connector, but that usually just means you can plug either in, not that the input is actually balanced. I believe that only the first two mono input channels on your mixer are actually balanced. And I don't think any of the outputs are. edit: yep, just read the manual. The only balanced thing on that mixer is the first two inputs.

Also worth considering: If a problem happens on the left channel but not the right, or vice versa, usually that means that one of the two cables or connectors is faulty.
drumphil is online now   Reply With Quote
Old 01-14-2017, 08:53 PM   #16
serr
Human being with feelings
 
Join Date: Sep 2010
Posts: 12,562
Default

Quote:
Originally Posted by foxAsteria View Post
The noise interference generated by my PC, amplified by my mixer and outputted by my monitors is becoming intolerable. My PCIe soundcard and the mobo sound both have S/PDIF optical outs, so my question is:

Is there such a thing as a small optical S/PDIF input mixer?
(preferably <$30) It also needs to have a DAC, but the quality doesn't need to be stellar.

In my quest to rid myself of this cacophony I've determined that optical signals don't suffer this noise problem, but the closest I've found is a 2 input switch on Amazon. I need 2-3 optical signals to be simultaneous, with independent volume control. Maybe "optical mixer" isn't the right term, but you get the idea...

Alternatively, I'd be willing spend around $100-200 or so to simply replace my Xenyx1002FX mixer with something that can do this.
I'd upgrade to a firewire or USB audio interface and eliminate the problem at its source. Even a modest Focusrite or Presonus unit wouldn't have gross interference issues like a Sound Blasticator card and it would be in that target price range. Shop for the integrated digital mixer, routing, and inputs/outputs you need.

More bang for the buck than an old school small analog mixer and I don't believe you'll find a small digital mixer like that.
serr is offline   Reply With Quote
Old 01-14-2017, 08:55 PM   #17
drumphil
Human being with feelings
 
drumphil's Avatar
 
Join Date: Jun 2006
Location: Australia
Posts: 3,738
Default

Quote:
But if I'm only hearing the noise through the monitors, you reckon it's just because the mixer doesn't have balanced outs? I guess I wouldn't mind replacing that cheap old thing...
That's probably it, BUT if you use the balanced inputs on your mixer you could break the ground loop there at the inputs, rather than breaking it at the outputs with balancing.

The downside is then you no longer have your two mic channels to use for recording.
drumphil is online now   Reply With Quote
Old 01-14-2017, 08:56 PM   #18
drumphil
Human being with feelings
 
drumphil's Avatar
 
Join Date: Jun 2006
Location: Australia
Posts: 3,738
Default

Quote:
Originally Posted by serr View Post
I'd upgrade to a firewire or USB audio interface and eliminate the problem at its source. Even a modest Focusrite or Presonus unit wouldn't have gross interference issues like a Sound Blasticator card and it would be in that target price range. Shop for the integrated digital mixer, routing, and inputs/outputs you need.

More bang for the buck than an old school small analog mixer and I don't believe you'll find a small digital mixer like that.
We already know for a fact that that isn't the source of the problem. The EMU 1212m actually has some of the best fidelity around! His sound card has balanced outputs, and when connected to the mixer without the speaker connection causing a ground loop, there is no noise. The noise only happens when an unbalanced connection is made to the monitors, that have a three pin power plug, linking their ground to the PC through the power board.

Ya'll need to go and read the rane notes I posted earlier before you leap to more spurious conclusions.

Last edited by drumphil; 01-14-2017 at 09:01 PM.
drumphil is online now   Reply With Quote
Old 01-14-2017, 09:07 PM   #19
foxAsteria
Human being with feelings
 
foxAsteria's Avatar
 
Join Date: Dec 2009
Location: Oblivion
Posts: 10,255
Default

I was wrong before. There is noise on the headphone out of the mixer. I had a defeat switch on by accident. Using the XLR ins increases the noise massively, I guess due to the preamps accepting a line level signal.
__________________
foxyyymusic
foxAsteria is offline   Reply With Quote
Old 01-14-2017, 09:08 PM   #20
drumphil
Human being with feelings
 
drumphil's Avatar
 
Join Date: Jun 2006
Location: Australia
Posts: 3,738
Default

Do you have TRS cables to make a balanced connection to the line in plugs on the first two channels rather than the XLR plugs? And I'm assuming you are doing this with the speakers disconnected and on board sound disconnected from the EMU? Plug one cable in at a time while listening through the headphones to make sure it isn't a dodgy cable. Test with each cable individually.

edit: Actually, here is a good test. Go straight from the balanced outs on your sound card, directly to the speakers with balanced cables. Do your speakers have balanced inputs? Are your jack cables actually TRS (balanced), or just TS (unbalanced)? Is the noise still there?

Aaaaand, are you doing this at sensible gain levels? Play a normal song through the system, and set the channel gain and headphone volume to a reasonable level. Is the noise still audible?

Last edited by drumphil; 01-14-2017 at 09:22 PM.
drumphil is online now   Reply With Quote
Old 01-14-2017, 09:22 PM   #21
foxAsteria
Human being with feelings
 
foxAsteria's Avatar
 
Join Date: Dec 2009
Location: Oblivion
Posts: 10,255
Default

Quote:
Originally Posted by drumphil View Post
Do you have TRS cables to make a balanced connection to the line in plugs on the first two channels rather than the XLR plugs? Yes Do your speakers have balanced inputs? yes Are your jack cables actually TRS (balanced), or just TS (unbalanced)? TRS Is the noise still there?
Ack, the noise is still there, but pretty reasonably quiet.
__________________
foxyyymusic
foxAsteria is offline   Reply With Quote
Old 01-14-2017, 09:37 PM   #22
drumphil
Human being with feelings
 
drumphil's Avatar
 
Join Date: Jun 2006
Location: Australia
Posts: 3,738
Default

So, that's with the sound card connected directly to the speakers?

The next test is to get (or modify) some TRS cables with the shield disconnected. This will break the ground connection between the sound card and the speakers, while still allowing the audio to flow over the remaining two wires.

Now, this shouldn't be necessary, but because reasons (consult the rane notes) most off the shelf cables have the shield connected, which shouldn't matter, but for a lot of gear it does. You should just be able to get an off the shelf balanced cable, and connect any bit of balanced gear to any other bit of balanced gear with the shield connected, but in reality it doesn't work that way.

But anyway, leaving the mixer out of it and connecting the sound card directly to the speakers is a good test. The next test is doing the same with with the shield disconnected. If you still get noise then, then the fault either lies with the speakers, or the sound card, or possibly the PSU in the computer. But it's still most likely a ground loop issue until everything that can be done to eliminate such issues has been tested.


Sound card direct to speakers is the best test, because it's balanced out to balanced in. The only remaining issue there can be the shield connection causing a ground loop. If that doesn't fix it, then we start looking at other issues.

Last edited by drumphil; 01-14-2017 at 09:48 PM.
drumphil is online now   Reply With Quote
Old 01-14-2017, 09:59 PM   #23
foxAsteria
Human being with feelings
 
foxAsteria's Avatar
 
Join Date: Dec 2009
Location: Oblivion
Posts: 10,255
Default Tenable Workaround

Ok, thanks much drumphil and everyone for your time and suggestions. Running the mobo into the E-Mu via optical and using balanced cables throughout the rest, I think I've got the noise to a tolerable level. I'll read those Rane docs later and get some more edjumucation on them fundumbentals reel soon. Still wish someone could answer my original question though.
__________________
foxyyymusic
foxAsteria is offline   Reply With Quote
Old 01-14-2017, 10:28 PM   #24
drumphil
Human being with feelings
 
drumphil's Avatar
 
Join Date: Jun 2006
Location: Australia
Posts: 3,738
Default

Cool. You still need to do the sound card direct to speakers test though. That should work with balanced cables, and if it eliminates the noise, would prove that the noise wasn't coming from the sound card.

Balanced cables throughout the rest doesn't mean much at the moment, as only the sound card to mixer ch 1 and 2, is possible to be balanced.

So, please do that last test, as it removes the mixer from the equation, and should provide decent insight into the situation.
drumphil is online now   Reply With Quote
Old 01-14-2017, 11:13 PM   #25
serr
Human being with feelings
 
Join Date: Sep 2010
Posts: 12,562
Default

Quote:
Originally Posted by drumphil View Post
We already know for a fact that that isn't the source of the problem. The EMU 1212m actually has some of the best fidelity around! His sound card has balanced outputs, and when connected to the mixer without the speaker connection causing a ground loop, there is no noise. The noise only happens when an unbalanced connection is made to the monitors, that have a three pin power plug, linking their ground to the PC through the power board.

Ya'll need to go and read the rane notes I posted earlier before you leap to more spurious conclusions.
Fair enough. If balanced cables (usually always a good idea) solve the problem, that's perfect.

If not and workarounds start making compromises and still involve spending money, then a more featured interface might be the easier path.
serr is offline   Reply With Quote
Old 01-14-2017, 11:52 PM   #26
foxAsteria
Human being with feelings
 
foxAsteria's Avatar
 
Join Date: Dec 2009
Location: Oblivion
Posts: 10,255
Default

Quote:
Originally Posted by drumphil View Post
Cool. You still need to do the sound card direct to speakers test though.
That's the test I was referring to in post 21 but I guess that's not clear. The noise was still there whether I connect directly to the line ins or the XLR ins (balanced cables in both instances).

Quote:
Originally Posted by drumphil View Post
only the sound card to mixer ch 1 and 2, is possible to be balanced.
Why do you say that? All of the other ins have "balanced or unbalanced" written next to them.
__________________
foxyyymusic

Last edited by foxAsteria; 01-15-2017 at 12:11 AM.
foxAsteria is offline   Reply With Quote
Old 01-15-2017, 02:03 AM   #27
somebodyelseuk
Human being with feelings
 
somebodyelseuk's Avatar
 
Join Date: Jun 2011
Location: Birmingham, UK
Posts: 1,125
Default

Big thanks to 'drumphil'.
Been having the same problems with a similar setup. Snipped the screens on the 1/4 end of the balanced speaker cables. Problem solved.
Now for the next issue...
__________________
"As long as I stay between the sun & my shadow, I guess I'm doing well."
somebodyelseuk is offline   Reply With Quote
Old 01-15-2017, 02:34 AM   #28
foxAsteria
Human being with feelings
 
foxAsteria's Avatar
 
Join Date: Dec 2009
Location: Oblivion
Posts: 10,255
Default

Quote:
Originally Posted by somebodyelseuk View Post
Snipped the screens on the 1/4 end of the balanced speaker cables. Problem solved.
Seriously? I wasn't willing to mutilate any cables to test this principle but now I'm curious. Can you describe your system please and which cables you modified? I have yet to read that whole technical doc.
__________________
foxyyymusic
foxAsteria is offline   Reply With Quote
Old 01-15-2017, 03:30 AM   #29
somebodyelseuk
Human being with feelings
 
somebodyelseuk's Avatar
 
Join Date: Jun 2011
Location: Birmingham, UK
Posts: 1,125
Default

Quote:
Originally Posted by foxAsteria View Post
Seriously? I wasn't willing to mutilate any cables to test this principle but now I'm curious. Can you describe your system please and which cables you modified? I have yet to read that whole technical doc.
LOL

No problem. I'm strictly a hobbyist and the cables aren't THE most expensive around, so I thought, 'sod it, try it out - I can always get the soldering iron out if it doesn't solve it.'
Pop into your local music shop and buy a pair of Stagg cables - maybe 10-20 pounds/dollars - and try it out on those first if you're worried about buggering up your cables... it's always handy having spare cables, anyway.
I'm running an M Audio AP2496 card to a Mackie 402VLZ4 to a pair of Yamaha HS50Ms.
I recently had to rebuild my PC - pretty much new everything, except the soundcard. I never had this problem on the old PC, so I was torn between a groundloop, knackered component on the soundcard or the obsolete driver somehow causing problems - Windows 7 driver on Windows 8.1 OS.
Anyhoo, whilst I'm not earning a living doing this, I have been dabbling with it for 35 years. My advice to you would be - learn to use a soldering iron, don't spend crazy money on cables unless you're earning it back - generally speaking, expensive cables don't sound any better, they are just much more robust and reliable.
__________________
"As long as I stay between the sun & my shadow, I guess I'm doing well."
somebodyelseuk is offline   Reply With Quote
Old 01-15-2017, 07:57 AM   #30
drumphil
Human being with feelings
 
drumphil's Avatar
 
Join Date: Jun 2006
Location: Australia
Posts: 3,738
Default

Quote:
Originally Posted by foxAsteria View Post
That's the test I was referring to in post 21 but I guess that's not clear. The noise was still there whether I connect directly to the line ins or the XLR ins (balanced cables in both instances).
So just to be clear, this is connecting from the sound card directly to the speakers, without the mixer being involved in any way? And using balanced TRS and XLR cables for the comparison? Well, actually, because your sound card only has TRS outputs, it would have to be TRS from sound card to TRS in on the back of the speaker, or TRS from the sound card through a lead with XLR on the other end directly to an XLR connector on the back of the speaker?

If so, and there was still noise, then you need to look at disconnecting the shield.

Quote:
Why do you say that? All of the other ins have "balanced or unbalanced" written next to them.
That's because you can plug a balanced output into them and it will still basically work, even though the input isn't balanced, and you're not getting the benefits of a balanced circuit. Those inputs aren't balanced, just compatible with being plugged into a balanced output. Your mixer only has two balanced inputs (ch1 and ch2), and no balanced outputs.

Last edited by drumphil; 01-15-2017 at 08:05 AM.
drumphil is online now   Reply With Quote
Old 01-15-2017, 08:04 AM   #31
drumphil
Human being with feelings
 
drumphil's Avatar
 
Join Date: Jun 2006
Location: Australia
Posts: 3,738
Default

Quote:
Originally Posted by somebodyelseuk View Post
Big thanks to 'drumphil'.
Been having the same problems with a similar setup. Snipped the screens on the 1/4 end of the balanced speaker cables. Problem solved.
Now for the next issue...
Happy to help

Shielding doesn't actually really work at audio frequencies, so you lose basically nothing by getting rid of it. But shielding does have a negative, that is connecting the grounds between bits of gear together.... which shouldn't cause a problem if everything was designed properly. But.. well....

So, disconnecting the shield removes a potential ground loop, and costs you nothing in sound quality.

If you are transmitting RF frequencies down a cable shielding might matter more, but for audio purposes the noise rejection and ground loop immunity of balanced connections are the important bits. Shielding and balancing aren't the same thing, even though you can get both in the same cable, with positive and negative phase signal (the balanced audio bit), and a shield round those two cables (the RF shielding bit), hence your three pins on an XLR cable.

Last edited by drumphil; 01-15-2017 at 08:19 AM.
drumphil is online now   Reply With Quote
Old 01-15-2017, 01:03 PM   #32
foxAsteria
Human being with feelings
 
foxAsteria's Avatar
 
Join Date: Dec 2009
Location: Oblivion
Posts: 10,255
Default

Yea I have tried TRS to XLR cables as well as just TRS to the line in from the card to the speakers directly. Still noise. The balanced cables did reduce the noise significantly in comparison to TS cables I was using previously. I can still hear it, but it's not constantly distracting anymore.

@somebodyelseuk which cables did you snip? Between the soundcard and mixer or mixer and speakers? I know how to solder, I just tend to avoid doing it. Also, I lost my soldering iron and need a new one.
__________________
foxyyymusic

Last edited by foxAsteria; 01-15-2017 at 01:10 PM.
foxAsteria is offline   Reply With Quote
Old 01-15-2017, 01:59 PM   #33
cyrano
Human being with feelings
 
cyrano's Avatar
 
Join Date: Jun 2011
Location: Belgium
Posts: 5,246
Default

Maybe you don't need to cut pin 1 on the XLR.

You could try insulating the audio card's metal bracket from the computer's chassis with some tape. Avoid screwing it back in. Use a tie-wrap for the test and get a nylon screw if it helps and you want to make the solution permanent.

It could also mean you need to take a long and hard look at you computer's PSU. It could be close to dying, in which case it would be wise to replace it now, before it takes some other parts of the computer with it when dying.
__________________
In a time of deceit telling the truth is a revolutionary act.
George Orwell
cyrano is offline   Reply With Quote
Old 01-15-2017, 05:46 PM   #34
drumphil
Human being with feelings
 
drumphil's Avatar
 
Join Date: Jun 2006
Location: Australia
Posts: 3,738
Default

Also worth trying: re-seating the sound card. Fixed a noise problem with a PCIe X-Fi card by doing that.
drumphil is online now   Reply With Quote
Old 01-15-2017, 05:54 PM   #35
serr
Human being with feelings
 
Join Date: Sep 2010
Posts: 12,562
Default

FYI on cutting the ground on one side of a cable.

You do this to eliminate a ground loop. The shield still physically covers the length of wire in the cable like a Faraday cage but "drains" any "collected" noise to one end.
serr is offline   Reply With Quote
Old 01-16-2017, 12:22 AM   #36
somebodyelseuk
Human being with feelings
 
somebodyelseuk's Avatar
 
Join Date: Jun 2011
Location: Birmingham, UK
Posts: 1,125
Default

Quote:
Originally Posted by foxAsteria View Post
@somebodyelseuk which cables did you snip? Between the soundcard and mixer or mixer and speakers? I know how to solder, I just tend to avoid doing it. Also, I lost my soldering iron and need a new one.
Mixer>Speaker. The screen tag of the TRS end of the TRS-XLR cable.
__________________
"As long as I stay between the sun & my shadow, I guess I'm doing well."
somebodyelseuk is offline   Reply With Quote
Old 01-16-2017, 05:15 AM   #37
drumphil
Human being with feelings
 
drumphil's Avatar
 
Join Date: Jun 2006
Location: Australia
Posts: 3,738
Default

His mixer doesn't have balanced outputs.

And, it would be better to try the disconnected shield cable directly between the sound card and speakers first, to reduce the number of variables.
drumphil is online now   Reply With Quote
Old 01-16-2017, 09:17 AM   #38
planetnine
Human being with feelings
 
planetnine's Avatar
 
Join Date: Oct 2007
Location: Lincoln, UK
Posts: 7,924
Default

This all sounds to me like switch-mode PSU noise being put on the ground plane of the computer. We get this issue quite a bit on laptops with PA rigs and have to place ground-lifted DI boxes in the signal lines to separate the ground planes.
It's a type of ground loop -different potentials on different signal grounds causes current to flow on the screens and manifests as noise.



>
__________________
Nathan, Lincoln, UK. | Item Marker Tool. (happily retired) | Source Time Position Tool. | CD Track Marker Tool. | Timer Recording Tool. | dB marks on MCP faders FR.
planetnine is online now   Reply With Quote
Old 01-16-2017, 12:25 PM   #39
somebodyelseuk
Human being with feelings
 
somebodyelseuk's Avatar
 
Join Date: Jun 2011
Location: Birmingham, UK
Posts: 1,125
Default

Quote:
Originally Posted by drumphil View Post
His mixer doesn't have balanced outputs.

And, it would be better to try the disconnected shield cable directly between the sound card and speakers first, to reduce the number of variables.
Yup, but my soundcard doesn't have the required outputs - AP2496 = unbalanced RCA.
Connected directly with RCA>XLR cable = noisy.
AP2496 > 402vlz (RCA>RCA) > 2x HS50M (TRS>XLR) = noisy.
AP2496 > 402vlz (RCA>RCA) > 2x HS50M (TRS>XLR w/screen snipped) = quiet = one happy bunny
__________________
"As long as I stay between the sun & my shadow, I guess I'm doing well."
somebodyelseuk is offline   Reply With Quote
Old 01-16-2017, 12:36 PM   #40
serr
Human being with feelings
 
Join Date: Sep 2010
Posts: 12,562
Default

Quote:
Originally Posted by drumphil View Post
The EMU 1212m actually has some of the best fidelity around!
Um... no. It's a very modest low budget pci audio interface. That doesn't make it "bad". It is what it is.

If we're now to the point where it's out of its league and isn't doing the job well, you can find a more pro firewire or USB interface for $100 - $200 that will simply work without hassles and workarounds. And probably be a stunning upgrade for sound and features. (Including a digital mixer built-in and so forth.)

By all means, fix a connection problem if that is the root cause! If it turns out to be 100% the cause, OK good, then we're done here.

If not, banging your head against the wall over a $90 Soundblasticater style card isn't the way to go. (That thing even has the audio jacks right on the freakin' card! There will be noise! It's meant for portable standards at best.)
serr is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -7. The time now is 03:25 AM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.