[negitoro7]

I just picked up a 7.1 system, Panasonic SC-HT200 and hooked it up to my computer via RCA audio cables.


There's a constant buzzing coming from the subwoofer, doesn't matter if I mute all sounds from the computer, the buzzing doesn't go away. Checked that the plug is fully inserted. Tested the same RCA cable by hooking up the Xbox 360 to the sound system, and there's no buzzing. Checked other audio sources and the speakers and sub work fine when playing a DVD or using hte ipod dock.


What the heck is the signal coming from the computer that's causing the subwoofer to buzz, even when nothing is playing? I have an Auzentech X-Plosion soundcard, my old speakers work just fine using the same connection (no buzzing). I'm really really stumped.

 

[bluesky636]



Quote:
Originally Posted by negitoro7 /forum/post/16955317


I just picked up a 7.1 system, Panasonic SC-HT200 and hooked it up to my computer via RCA audio cables.


There's a constant buzzing coming from the subwoofer, doesn't matter if I mute all sounds from the computer, the buzzing doesn't go away. Checked that the plug is fully inserted. Tested the same RCA cable by hooking up the Xbox 360 to the sound system, and there's no buzzing. Checked other audio sources and the speakers and sub work fine when playing a DVD or using hte ipod dock.


What the heck is the signal coming from the computer that's causing the subwoofer to buzz, even when nothing is playing? I have an Auzentech X-Plosion soundcard, my old speakers work just fine using the same connection (no buzzing). I'm really really stumped.

The problem is clearly the computer. You either have a ground loop in the computer audio output or a bad internal connection. Repair or replace the computer.

 

[Espo77]



Quote:
Originally Posted by negitoro7 /forum/post/16955317


I just picked up a 7.1 system, Panasonic SC-HT200 and hooked it up to my computer via RCA audio cables.


There's a constant buzzing coming from the subwoofer, doesn't matter if I mute all sounds from the computer, the buzzing doesn't go away. Checked that the plug is fully inserted. Tested the same RCA cable by hooking up the Xbox 360 to the sound system, and there's no buzzing. Checked other audio sources and the speakers and sub work fine when playing a DVD or using hte ipod dock.


What the heck is the signal coming from the computer that's causing the subwoofer to buzz, even when nothing is playing? I have an Auzentech X-Plosion soundcard, my old speakers work just fine using the same connection (no buzzing). I'm really really stumped.

If you are using a lap top, unplug it from the ac and use the battery, just to confirm that you have a ground loop.

 

[Espo77]



Quote:
Originally Posted by bluesky636 /forum/post/16955369


The problem is clearly the computer. You either have a ground loop in the computer audio output or a bad internal connection. Repair or replace the computer.

WOW!

Not so fast..............it's most likely an ac ground loop.

 

[Harrypt]

Computers make poor analog audio devices. Your easiest and cheapest option is to use an optical digital connection if available. This breaks the electrical connection that is transferring the noise to the Panasonic.

 

[negitoro7]

Thanks all. My soundcard does have optical out, so I just ordered a long enough cable from monoprice.

 

[bluesky636]



Quote:
Originally Posted by Espo77 /forum/post/16955410


WOW!

Not so fast..............it's most likely an ac ground loop.

Yeah. Caused by the computer since that is the only component to exhibit the problem when hooked up.

 

[jarrod1937]



Quote:
Originally Posted by Harrypt /forum/post/16955432


Computers make poor analog audio devices.

Wow, that is a very funny statement... considering all other audio devices these days are basically specialized computers.

Analog audio can sound great from a computer, you just need a quality sound card.

 

[Gizmologist]

This is a very common problem and there are many companies that have built impedance matching and hum elimination interfaces specifically for this.


My company builds them for stereo to stereo L/R XLR balanced out, PC to mic input, and every other permutation needed.


There is nothing inherently wrong with your computer.

 

[ChrisWiggles]



Quote:
Originally Posted by bluesky636 /forum/post/16956859


Yeah. Caused by the computer since that is the only component to exhibit the problem when hooked up.

Uh, no. If it's a ground loop, then the problem is not the computer at all, but the ground loop that happens to be going through the computer. Buy a new computer, hook it up, you'll still have buzz if it's a ground loop. We haven't actually ascertained what the cause of the buzz is, so you're being quite silly in assuming that the computer is at fault when it may have nothing at all to do with the computer. Seeing as how buzz in subwoofers is usually a ground loop problem, it seems your advice is very much ill-placed.

 

[Ugly1]



Quote:
Originally Posted by negitoro7 /forum/post/16955450


Thanks all. My soundcard does have optical out, so I just ordered a long enough cable from monoprice.

I agree that it is probably caused from a ground loop. If it is then the optical link will most likely solve the issue.

 

[Ugly1]



Quote:
Originally Posted by Gizmologist /forum/post/16957008


There is nothing inherently wrong with your computer.

Well other than it is just falling in line with the rest of consumer audio equipment industry with respect to eliminating this type of issue by design. I happen to be of the opinion the whole single ended "grounding" scheme being propagated forward by the companies participating in this market is broken and the equipment utilizing it is then broken by default even while operating flawlessly per manufacturer specs.

 

[Gizmologist]

Sort of, but until all the audio manufacturers find a cost effective reason to start using strictly balanced system we must accommodate them.


Until then the fix is very easy use a transformer to isolate the 2 systems

 

[Ugly1]

I agree that it is AN approach. To get transformers which get somewhat close to approaching linear for the whole audible band will cost you, especially if you want to try and push any power through there. Even the best transformers, however, still impart their own "sound". Some people even like it I hear.


Personaly I would prefer to see a move toward breaking the analog link entirely and instead transmit hi res digital data wirelessly to powered, isolated speakers with their own decoders and DACs. Proper data encryption via some new round of standardized hardware could even ensure a sufficient level of security to satisfy the HDCP Nazis.


Obviously it would take some sort of miracle for the whole industry to pick up and move to something like that but hey I can always dream. If you think it's painful now waiting for the smaller manufacturers to come out with hi res multi channel hdcp enabled boxes, just wait until you see these audio dudes attempting to do radio. haha.

 

[Gizmologist]

These can easily handle up to +24db. These are made by OpAmp labs in SoCal or you can readily find Jensen xformers for about 40 each for the serious HD series.


However considering the usual quality of computer audio from uploads etc, much less expensive xformers will frequently suffice.

 

[ChrisWiggles]



Quote:
Originally Posted by Ugly1 /forum/post/16957284


Well other than it is just falling in line with the rest of consumer audio equipment industry with respect to eliminating this type of issue by design. I happen to be of the opinion the whole single ended "grounding" scheme being propagated forward by the companies participating in this market is broken and the equipment utilizing it is then broken by default even while operating flawlessly per manufacturer specs.

Stop blaming the equipment for a grounding issue. If it's a grounding issue it's not the equipment's fault! Bonding/grounding is the issue, you fix that, not blame the equipment or try to fudge around the problem by fudging it with transformers, isolators, ground lifers, etc.

 

[Gizmologist]

Isolation transformers are THE accepted way to isolate 2 or more devices with ground loop conflicts if optical interconnects are not an option. We use them for audio and video all the way to HDMI signals. Thee is no signal degradation with a well designed transformer.


The post about single ended ground problems in the industry was tongue-in- cheek. The idea was that unbalanced ground referenced signals are inherently inclined for problems in ground loops and also in impedance mismatching.


Single ended unbalanced interconnects are cheaper to design and build but they do have serious drawbacks.

 

[Speedskater]

In the past, I have run an external ground wire from the case of one unit to the case of the other unit. With a fork lug on each end of the wire, I connected to a case screw of each unit.

 

[Ugly1]



Quote:
Originally Posted by ChrisWiggles /forum/post/16959755


Stop blaming the equipment for a grounding issue.

Why would I? Better designed equipment wouldn't have the problems dealing with grounding issues that gear does now which you buy at your local electronics retailer.

Quote:
Bonding/grounding is the issue, you fix that, not blame the equipment or try to fudge around the problem by fudging it with transformers, isolators, ground lifers, etc.

I disgree that it should be a requirement or even reasonable to expect that consumers who want good sound attain the technical knowledge necessary to first identify and solve or pay to have solved the underlying grounding problems if the stuff they buy sounds like crap when they plug it in and try using it. At least not in the light that eliminating this problem wouldn't take much other than a well planned industry standard designed to avoid it.


For example symptoms like buzzing can be caused by haphazardly attaching equipment to wiring layouts meeting code. An electrician will not have the expertise to address ground loop issues caused by ground loops within house wiring which is well grounded per his code handbook. Who does Joe sixpack call when the electrician tells him nothing is wrong and the system still sounds bad? Probably the salvation army to haul off his broken gear.

Quote:
Originally Posted by Gizmologist /forum/post/16960342


Thee is no signal degradation with a well designed transformer.

I disagree. It is impossible for this statement to be true. Transformers are all nonlinear devices. It is only a matter of degree. I concede it is true that a well designed transformer may not cause noticeable distortions. To attain a transformer of this level of quality can be extremely expensive even for low level signals such as line level signals. When you start to talk about amplifier output level signals, well, you better get a truck to haul your money into the transformer store because you are going to need piles of money to achieve true transformer transparency for anyone who can still hear. To me the requirement to dump piles of money on transformers doesn't seem like the best solution either.


The radio idea I brought up could allow equal or better performance for much lass cash outlay AND could be implemented such that it does not require a phd in transformer design or proper grounding techniques to set up sounding great. It fully leaves the burden of a good design on manufacturers who rightly should be experts rather than the consumers who rightly should be allowed to be completely ignorant.

 

[Gizmologist]

True, transformers are not truly linear. HOWEVER the human ear and eye are not linear either. The entire media industry -BAR NONE- processes audio and video through transformers of various kinds.


If the only way to document some form of non linearity or "transparency" in a signal is to use sophisticated scopes etc (which I have) and there is no apparent flaw noticeable by the human eye or ear that seriously degrades the signal, then what is the concern?