PC Electrical Noise: How Do You Solve It?

Jayster wrote on 7/8/2006, 8:21 PM

I am trying to do some noise reduction on a video project. Unfortunately it's impossible because of the incredible amount of noise generated by my PC itself! It's electrical noise, not only fan noises. It's a system I put together in March with all new components.

System Info
Sound card: built-in mobo 7.1 channel (from Asus A8NSLI32-Deluxe)
Speakers: Klipsch THX-certified 4 speaker + sub 160W RMS system
External Sound Connections: no mics, no MIDI, only line out to speakers
Power Source to PC & Speakers: UPS
PC Power Supply: Sunbeamtech NUUO 550
PC Case: Lian-Li PC-6077 Silver Aluminum Case
(additional info in my profile)

I'm experiencing a lot more than just fan noise. I hear a constant staticy sound. When a hard drive spins, I hear it across the speakers. When I move a window with the mouse, I get a buzzing sound. (Oh yeah, and the fan on my power supply is thumping and whacking the grill, but I'll be sending it back to the factory ASAP so this isn't the only problem). For a test I connected the amplified speakers to a 2nd PC and there was zero noise, so I think the problem is not in the speakers. Also, as noted above, I am not connecting any external inputs to the sound card (no microphones, MIDI, etc.). I will want to connect a simple PC mic, but I pulled it in the hopes of eliminating the noise.

I read an article on a site about DAWs that says its caused by ground loops. I did their suggestions (tightened all connections, made sure that the PC and the amplified speakers have the same power connection, which in my case is a UPS, and I even put an isolation transformer in the sound signal path from the PC to the speakers). Nothing helped. I even checked with a mulitmeter and found no impedance between the PC chassis and the earth pin on the power supply (but I know that a power supply can fool you because its transformer coils will show zero impedance).

The site said the PC power supply can be the source of the problem (i.e. if it has grounding problems). Maybe I'll get lucky and they'll fix a ground problem when I send it back, but I'm not counting on it.

If the repaired PC power supply doesn't stop it, I'm wondering if instead of spending another $80-$120 on a different power supply, perhaps the next step is to purchase an external sound card and connect it by FW. Would that solve the problem? If so, what brand & model of sound card should I purchase?

I'm not running a music studio. No MIDI connections are needed. I just want to be able to edit videos (including 5.1 AC-3). I want to hear the noise from my videos (so I can correct it), not the noise from my PC! But maybe some day I could connect an external digital recorder to the PC (like you would use to digitally record from a sound board at a music concert).

Any advice would be most appreciated:-)

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Comments

John_Cline wrote on 7/9/2006, 3:24 PM

Under normal AC conditions, a UPS does NOT convert AC to DC to AC, it just filters and passes the AC coming out of the wall. It is only during blackouts (or brownouts) that the battery-powered inverter kicks in. The UPS isn't the cause of your problem.

John

gordyboy wrote on 7/9/2006, 4:10 PM

I don't know about the USA - here in the UK, electrical mains plugs are three pronged - carrying live, neutral and earth. To check for an earth loop, all I had to do was *temporarily* disconnect the earth wire from the mains plug.

ie disconnect the green and yellow wire as shown in this diagram.

How to wire a basic British 13 amp plug

gb

TheHappyFriar wrote on 7/9/2006, 4:45 PM

what kind of lighting do you have in the room? And is the lighting on the same circuit as the socket the PC is plugged in to? That can cause problems (especially florecents, those generate a hum that anything can pick up).

fldave wrote on 7/9/2006, 5:06 PM

Jayster,

Essentially, your PC is filled with a bunch of "radio receivers" and "radio transmitters". Can't get around that. Nature of the beast. I had one PC that was rated FCC Class A (US commercial only) that any sound card in it screamed. FCC Class B is home use, and is much more stringent than class A. All it takes is just one out of whack component and the whole system messed up.

Your best bet is external sound card, then disable the internal one.

"Currently there are no FCC regulations pertaining to product immunity to electromagnetic fields. "

http://www.emclab.umr.edu/emcproc.html

Commercial Products Marketed in the USA

The FCC Rules and Regulations, Title 47, Part 15, Subpart B regulates "unintentional radio-frequency devices". Products regulated include any unintentional radiator (device or system) that generates and uses timing pulses at a rate in excess of 9000 pulses (cycles) per second and uses digital techniques. This includes almost every product that employs a microprocessor including workstations, personal computers, point-of-sale terminals, printers, modems, and many electronic games. It is illegal to sell or advertise for sale any products regulated under Part 15, Subpart B until their radiated and conducted emissions have been measured and found to be in compliance.

Most products regulated by Part 15, Subpart B fall into one of two categories. Class A devices are those that are marketed for use in a commercial, industrial or business environment. Class B devices are those that are marketed for use in the home. Class B limits are more stringent than Class A limits and the Class B certification process is administratively more rigorous than the Class A verification process. The radiated and conducted EMI test procedures are defined in the ANSI Standard C63.4. FCC Rules and Regulations, Part 15, only regulates radio frequency emissions. Currently there are no FCC regulations pertaining to product immunity to electromagnetic fields.

Jayster wrote on 7/9/2006, 5:35 PM

I think I am fast concluding that I agree with many posters here that I may be better off with an external sound card / audio interface. I am not considering one of the $20 USB cards that are common; I don't trust that for video / audio editing use. I saw that there is one made by Creative Labs, the Sound Blaster Audigy 2 NX. This appears to be a slightly old model. I am using 64 bit Windows XP (which gives me significantly better results with Vegas 6) and this card has a driver for it (the driver was released in August 2005). This card costs about $100 on the net. Not sure if this is a "legacy product" because it's drivers are all from mid 2005 and it doesn't show up at most of the PC stores I use on the Internet.

I am also considering a somewhat more expensive card ($160 for a "scratch and dent" version), the M-Audio FireWire Audiophile Computer Recording Interface. M-Audio only has a beta driver for Win XP x64 which was released in March 2005. But this card is FW instead of USB. It has a MIDI input, but I don't know if I'll ever have a use for that (never can tell, I guess). It has two sets of line outs, so I am assuming it can send outputs for a 4-speaker system.

Any thoughts on this? I guess I should look at the other card or two that someone recommended.

craftech wrote on 7/9/2006, 5:51 PM

Have you tried turning OFF your modem?

John

Jayster wrote on 7/9/2006, 5:52 PM

I don't have a modem. And I tried turning off all lighting in the room, to no avail.

TheHappyFriar wrote on 7/9/2006, 6:05 PM

use any extension chords?

Jayster wrote on 7/9/2006, 6:22 PM

The UPS is connected directly to the wall outlet, and my PC and speakers are powered by the UPS. I do have a different outlet with a power strip for a printer and a consumer TV and a laptop.

Blues_Jam wrote on 7/9/2006, 11:46 PM

"(Oh yeah, and the fan on my power supply is thumping and whacking the grill, but I'll be sending it back to the factory ASAP so this isn't the only problem). "

I believe that IS exactly the problem here. It makes sense from an electrical standpoint and explains the symptoms you describe. A current is delivered to the fan which is electrically an impedance provided by it's coil. Each 'whack' of a fan blade against the grill changes the impedance of the coil for a fraction of a second by increasing it's load, just like what happens in a vacuum cleaner motor if the hose gets clogged with a cloth or rug. In between each 'whack' the coil impedance returns to normal and the load is reduced. This creates a ripple voltage that is fed back into the power supply and the rest of your system and could easily be within the audible frequency range. It seems to me that the greater the current draw from within your system (such as during hard disk activity or video card demand), the greater the percentage of ripple voltage to total applied voltage and thus the greater the amplitude of the audio frequency.

Of course, then again, I could be wrong :)

At any rate, I would also suggest as others already have that any descent audio card would be preferrable to MoBo audio but don't waste your time and money trying to get rid of the noise until after your power supply is replaced.

Blues

Coursedesign wrote on 7/10/2006, 8:41 AM

Forget the Soundblaster.

Many many people have been reduced to crying from trying to make pro audio software work with Soundblaster drivers. You may be lucky, but why bother????

Not worth the aggro, get the M-Audio card or an Echo MIA card on eBay (I've seen them go for less than $60).

The MIA is my favorite in this price range, but it is 2-ch only.

Jayster wrote on 7/10/2006, 9:14 AM

Blues_Jam - this noise problem has been present since the day I put the system together, the fan whacking problem just started a few weeks ago. But in one sense you are totally right: the fan is an immediate problem that must be solved ASAP.

Coursedesign - according to Echo, their Mia product is now discontinued (but they say they will still support it). They have a new product that will release in July that looks quite nice called AudioFire4. I have no idea what it'll cost. None of Echo's products currently have 64-bit drivers, but they are saying they'll release drivers this summer.

Jayster wrote on 7/25/2006, 11:39 AM

Thanks everyone for your assistance on this one. I wanted to update you guys on how I've solved the problem.

After pulling out the power supply with the fan problem and sending it to Newegg, I pulled a power supply from a different PC and put it in this system. The noise reduced quite dramatically. So I think that the Sunbeam Nuotech power supply has a weakness in this area (poor signal grounding?). Now that I've got the replacement power supply in from Newegg and installed it (they sent me a brand new one, same model, what a great company!), well it has similar problems. I don't want to keep the other PC's power supply in this because it's got lower capacity, only 20 pin output, no VGA power cable, etc.

Meanwhile, I have implemented a real solution. I saw a website where it said that people who use pro audio workstations are well aware of the perils of noisy PC audio hardware, and they routinely solve it by doing the digital to analog conversion outside the PC. Many of you are saying "duh!" but I had never really gotten into audio editing before now. I had a gut feeling this was the only real solution, and now I am quite sure of it.

One of Coursedesign's comments gave me the idea. I purchased a set of 5.1 speakers that accepts a digital coax & fiber optic connection. It also decodes DTS and Dolby Digital. This totally solved the problem. And I can use it to listen to DVDs with 5.1 encoding. Not cheap (price went up since after I bought it), but it does the job beautifully. A really critical feature for me is the headphones connection on the unit. Doing noise reduction, etc. really requires using heaphones (IMO). The headphones connection straight off the sound card is unacceptably plagued by noise.

Later if I start doing any audio recording (like for adding narration VOs, etc.) I'll purchase on outboard audio interface, but for now I don't need that.

THANKS AGAIN TO ALL!