New speaker issue

[Renton Maclachlan]

I took the plunge and got some Wharfedale 8.1 Studio Monitors so that I could get some better sound when editing a video project than I have been getting from computer speakers...

They turned up this morning and a friend lent me cabling for them so I could get them going. The cable has a mini jack to go into the computer (actually I have a mini-jack cable coming from the computer, into which I plug either speakers - past or present ones, or my headphones for when the house needs to be quiet), which switches to two XLR plugs to go into the balanced inputs in the new speakers.

However there is a teething issue in getting them going correctly...there's interference of some sort occurring and I wonder if anyone here can tell me what it is...

When nothing is playing on the computer (though the computer is on) there is a light/soft hum and I supposed what you could call a sort of soft crackle - for want of a better word, coming from each speaker. This increases as you turn the volume up at each speaker.

When editing in Sony Vegas and using the phones I don't hear any of the interference at all and nor did I when using the old speakers. But as soon as I plug the new speakers in I do. It happens when I'm playing the timeline in Vegas and seems to occur at the transition between frames. I have a Shuttle pro which allows me to wind down the timeline a frame at a time and I hear it when doing this...also when playing at normal speed. Once again it is more pronounced when the volume is up at the speakers.

Not sure if it has anything to do with it but rather than plugging the speakers minijack into the lead from the computer, I touch my watch with it, I get a crackle thorugh the speaker (depending on which par of the plug hits my watch). The speakers are both powered of course and when I touch my watch the power is on and the two XLR's are plugged into the speakers.

Could it be something to do with the cable or its proximity to something else?

[Jay Massengill]

Computer mini-jack audio outputs are notoriously noisy with powered speakers. Plus it's probably a signal level mis-match and it's possible the cables you're using aren't correctly shielded or wired properly.

I always use a USB audio interface and good quality cables between my computer and mixer or monitor speakers.

This should cut down on noises coming from the computer and will allow you to use better connectors and cabling than a mini-jack to XLR converter cable.

If you really want 8.1, you'll need to use an interface that supports that. Or for just a low-cost stereo signal test, an interface like the Behringer UCA-222 is $30 everywhere. You would still need to convert from the RCA outputs of the Behringer to XLR if your new speaker system doesn't also have unbalanced inputs.

[Rick Reineke]

The noise could have been there all the time, but was not audible on the old speakers. In addition to decent speakers, the sound card/interface is just as important.

[Renton Maclachlan]

At present I don't use a sound card...son in law took it out saying the onboard sound was as good...
Board is Asus P8Z68 Delux/GEN 3...

[Richard Crowley]

So do the speakers have the same background noise when the computer is turned off? Or if you simply unplug the 3.5mm plug from the computer? As Mr. Massengill mentioned, the built-in sound circuits on computers are NOTORIOUSLY noisy. It is practically impossible to make them as quiet as from your average piece of audio gear.

You might want to get that sound card back from your son in law. But even an inexpensive EXTERNAL USB sound "dongle" is typically quieter than any high-end internal sound-card. What you describe hearing is quite possibly what your son-in-law describes as "good".

[Rick Reineke]

"the onboard sound was as good"
- As good as what? Consumer sound interfaces are notoriously far from flat (frequency response), and no experienced audio person would ever recommend them. Same goes for those 'designer' headphones for monitoring location audio.

[Renton Maclachlan]

I have the sound card here so could put in back in again...

I also could take a recording of the sound but it would have to be tonight...I have a zoom h6 so should get a pretty good recording...

The headphones I've got are Audio-Technica ATH-M50's

Richard...When the computer is turned off there is a very faint hum but it is not the same sound...haven't checked simply unplugging the 3.5mm plug...presume it would be the same as if the computer is off as either way nothing is coming from the computer...

Not sure what my son in law means by 'good'!

[Paul R Johnson]

There is a clue in the fact there's a faint noise with the computer off. If you can solder, then change the wiring on the xlr connectors to feed the ground to pin 3 and the signal to pin 2, leaving the pin 1 in connecting. I'm assuming your cable is currently wired with pin one connected to either 2 or 3 and the screen, with signal to the remaining pin? This loses the inherent balancing, but makes it susceptible to hums and noise to a small degree. Using pins 2 and 3 removes the connection to ground, and it operates in differential mode. This often helps with problem devices like PC laptops, especially Dell, who have well known interconnect problems with their power supplies. With grounds missing from such a lot of kit now, ground is rarely ground any longer.

[Renton Maclachlan]

Thanks Paul...I just posted the following over at the Vegas Forum, as someone there suggested the problem was the incompatibility of mini jack (unbalanced) and XLR (balanced)...

'I thought Adam you might be onto something so rang a friend who is an audio wiz and he confirmed your analysis.

So...seeing the speakers have unbalanced RCA inputs as well, I tried linking it all up with RCA cables...
but behold, the interference is still there.

I have attached a file recorded and maximized illustrating the sound as it occurs in Sony Vegas Pro. First is normal speed down the time line, then me winding along the timeline slowly using the Shuttle Pro. The video consists of me speaking, with various graphics replacing me and being shown...some are photos, some are png files. You distinctly hear the sound change when the cursor comes to a graphic or photo...

The audio volume has been wound right back except on one small section I where wind it up a bit then down again.

Friend suggests it could be interference from the power supply, as the current varies to deal with the graphics etc and the frames down the time line...

Next step is to put the sound card back in and see if that changes anything... '

[Paul R Johnson]

I posted in the other topic you started, but added stuff here. Sadly now you've posted the clip, it's clear it's bus noise, and quite common. Inside the metal box is the worst place for quiet audio. I assumed you were talking about hum, so sorry about that. My balancing trick won't work with this as the data shifting around the internal bus structure is leaking into the audio lines and it's not removable, nor is it something you are doing wrong. Some proper audio cards are properly screened, but on board chipsets aren't, nor are cheap Slot type cards. Audio performance isn't a real consideration. One card I loved started doing this when transplanted into a new computer, just one of those things. External d/a's seem immune from this because their sensitive electronics are remote from the dirty digital hash filled environment inside what is essentially a Faraday Cage. Even in mega expensive computers, the cost of the audio components is often pennies!

[Richard Crowley]

Completely ordinary, common and predictable "digital hash" from inside of the computer. That is exactly why I said "the built-in sound circuits on computers are NOTORIOUSLY noisy". The only way to eliminate that is to abandon the audio outputs from the computer and use an EXTERNAL sound device. Even a $30 Behringer UCA-222 has an infinitely better chance of eliminating that noise than a $300 INTERNAL sound card. And portable "laptop" computers are even worse because of their external power supplies.

[Jim Andrada]

I have an internal sound card that seems to be pretty damned noise free. On the other hand it was around $700 (Lynx L22) so I think I can agree with the comment that on-board adapters and lower cost cards are not likely to be sufficiently well shielded against PC noise.

[Renton Maclachlan]

Back again...

Interestingly...I am still getting the noise through one speaker, that by the computer (500mm from the motherboard)...but not from the one that is 1600mm from the computer....

[Jon Fairhurst]

I would definitely recommend an external, USB-based sound interface. While you can add an internal card, the industry has moved mainly to external solutions. Some nice advantages are easy access to the connectors and a nice, big volume knob within easy reach. :) Make sure to get a unit with balanced inputs and outputs. I'd get at least one XLR mic input with phantom power so you can get a mic for possible voiceovers in the future. Add some balanced lines from interface to speakers and you're set.

[Renton Maclachlan]

I have (just last week) got an external sound card...an Asus Xonar U7...