Buzzing sound from speakers

K

Kronen

New member
I'm in the process of setting up a home recording studio. Currently I'm using my PC to input straight into a PA system but I'm getting a constant buzz sound from the speakers. There is also another buzz whenever I move the mouse or type on the keyboard. I'm assuming this is because the audio jack is picking up changes in the electrical signals. Will this problem be resolved by buying an external audio interface? That was what was next on my to buy list.
 
It's usually an earthing problem, and it's associated somehow with PC power supplies and motherboard design. Laptops are notorious for doing this, but are silent when run off batteries.

A usual cure is to use balanced leads if you can.
 
Had had a buzz a while ago... Turned out to be the lamp on my desk... Switch it for a different lamp... No more buzzing.
 
gecko zzed said:
It's usually an earthing problem, and it's associated somehow with PC power supplies and motherboard design. Laptops are notorious for doing this, but are silent when run off batteries.

A usual cure is to use balanced leads if you can.
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++1
Ground loops can be a pain to find for sure. Unfortunately balanced leads doesn't always fix the issue.
 
If its a 60 hz buzz, probably a ground loop to your computer. If its a laptop, unplug it and if it goes away, you'll need to find a way to isolate your power supply, or lift the ground if its grounded. However, I have had instances with lower ended "comes with the box" sound cards that will bleed digital "noise" or a higher frequency variable buzzing that will modulate with mouse movements or keystrokes etc. If that is the case, you might try looking into an actual Input Output audio box that has the capabilities of balanced I/Os. If you are just starting out, that's the kind of stuff that you want to get on top of pretty quickly or frustration will set in. Like trying to learn to play on a guitar a professional cant even play! :) Good luck
 
There are various reasons why you are getting a buzz but the fact that it changes with mouse operation does pin it down fairly well to an earth loop.

If indeed you are using a laptop and the noise is stopped when on battery power that proves it to be an earth loop and THE very best solution is to try to find a power supply that does not carry the mains earth through to the laptop. A quick and dirty fix can be to remove the screen connection on the jack plug from the PC but this can leave you open to RF interference problems.

If in UK/EU look for Orchid Electronics who make an excellent earth isolator at a very reasonable price. Don't think they are available elsewhere but the Art Cleanbox ll is pretty ubiquitous.

Yes, do get a proper interface as soon as you can but no, it probably won't cure this problem. Yes again, balanced operation might fix it but in actual fact "balancing" is not really meant to fix earth loops but to reject interfering fields...IF it does the former it is probably by the better input topology of the gear.

Dave.
 
c7sus said:
Everybody needs a decent DI box. :D
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That, ^ may well be but let us not muddy the waters here? That which is called a "Direct Injection box is a device, usually single channel, that allows a mid-impedance device such as a passive electric guitar to feed a mic input with a balanced, low Z source. The internal transformers for the passive devices is usually around a 10:1 ratio.

For the OP's problem a pair of 1:1 transformers are required and at any given level of quality, distortion, frequency response, are much cheaper than high ratio types.

Actually this...http://www.inta-audio.com/cables-co...+listing+ads&gclid=CPrHya75jcMCFWXHtAodGmMAwQ is remarkably good for the money and is well worth having in the gigbag as a problem solver with a gaggle of adaptor leads. It can be used to prove a hum loop in a system then a higher "fi" device obtained later.



Dave.
 
ecc83 said:
That, ^ may well be but let us not muddy the waters here? That which is called a "Direct Injection box is a device, usually single channel, that allows a mid-impedance device such as a passive electric guitar to feed a mic input with a balanced, low Z source. The internal transformers for the passive devices is usually around a 10:1 ratio.

For the OP's problem a pair of 1:1 transformers are required and at any given level of quality, distortion, frequency response, are much cheaper than high ratio types.

Dave.
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Exactly what I was suggesting above.

Alan
 
Get an audio interface - instant better quality, properly designed audio stages with no noise. Oddly, Macbooks usually work brilliantly into PAs without DIs, and rarely have any noise. Dells seem universally the worst, with switch mode power supplies.

Simple trick - pull out the power supply for the laptop (assuming it is a laptop), and I bet the noise goes away. Most laptop power supplies are double insulated, so there should not even be any ground loops - but some make all sorts of noises.

If it's a desktop or rack PC with integral motherboard audio, then the bus data is often superimposed on the output - a proper sound card is usually immune from this stuff, but external ones are physically further from any noise.

One of my PCs has a Maya card in it and there is no noise at all - I rather like it.
 
ecc83 said:
That, ^ may well be but let us not muddy the waters here? That which is called a "Direct Injection box is a device, usually single channel, that allows a mid-impedance device such as a passive electric guitar to feed a mic input with a balanced, low Z source. The internal transformers for the passive devices is usually around a 10:1 ratio.

For the OP's problem a pair of 1:1 transformers are required and at any given level of quality, distortion, frequency response, are much cheaper than high ratio types.

Actually this...AV Link High Quality Ground Loop Isolator Noise Reduction Filter - Cables & Connectors from Inta Audio UK is remarkably good for the money and is well worth having in the gigbag as a problem solver with a gaggle of adaptor leads. It can be used to prove a hum loop in a system then a higher "fi" device obtained later.



Dave.
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RTFM. It's designed for patching computers to PA's, is stereo, is much more versatile than a 1:1 20-quid transformer, and does exactly what the OP is asking for.

Somebody else's budget isn't my problem.

http://www.radialeng.com/pdfs/smartsheet-radial-proav1.pdf
 
c7sus said:
RTFM. It's designed for patching computers to PA's, is stereo, is much more versatile than a 1:1 20-quid transformer, and does exactly what the OP is asking for.

Somebody else's budget isn't my problem.

http://www.radialeng.com/pdfs/smartsheet-radial-proav1.pdf
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Rude but never mind. It is just good commercial practice and sound engineering to use devices fit for purpose at the appropriate cost. Buying in redundant functions is not.

Dave.
 
ecc83 said:
Rude but never mind. It is just good commercial practice and sound engineering to use devices fit for purpose at the appropriate cost. Buying in redundant functions is not.

Dave.
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Pointing you to the manual for the product is rude?

My gig is building redundant function systems, Einstein. And it most certainly is "sound engineering use". If it wasn't customers wouldn't be spending billions on it.

LOL@ "good commercial practice" when the OP is about hooking up an internal laptop soundcard to a PA for monitoring while home recording.
 
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