Hi SuperG

I'm taking the Audio OUT directly from the MoBo's Audio OUT supply. The Audio IS integrated with the MoBo. No amplifier.

Powered Monitors and are working correctly. I can also switch the cabling to switch the hiss from one Monitor to the other. I've also checked the Audio output to a completely separate amp with its own monitor set. Same story. It isn't the PC's Monitor set of speakers nor cabling. Ugh . . .


"Is the PC audio device a PC bus add-on card."

No, it's integrated with the MoBo.

"It might be worth a try to unplug the PC from the wall (er, uh, mains) and check for hiss."

Good point, and that was also my concern too. If I unplug the PC then the hiss slowly disappears, not in volume, but its presence. It's there until it is gone, if you know what I mean, takes about 6 seconds, hence my thoughts on a degraded grounding component, something like a capacitor that slowly discharges.

Anything else? I'm game!

Grazie

"OK, even with PC off, but plugged into the mains with its own isolator ON,"

What is this "isolator" thing?
What if it's turned off, what if you plug the PC directly into the mains?

"To my uneducated electronics brain, it sounds/appears like a grounding component has gone bad on me."

Usually a ground fault causes HUM, not noise. A RF bypass component could have gone AWOL causing an RFI issue but that unlikely. If you have a UPS or power supply go sick it could create a lot of RFI that's swamping the audio card.

Sorry I'm not being much help really, very hard to diagnose these problems without being on site. Just try anything and everything to narrow it down.

Bob.

Bob, I can give you a sampler EARFUL over on Skype.

It does sound like crackle radio interference. Not a hum . . zzzststszzzzststs . that kinda thing?!? LOL!!

Anyway, I have SKYPE up. Wanna hear?

Grazie

" Wanna hear?"

Thanks for the offer but I know what it sounds like. I had a very minor version of it in one of my old systems that would make that kind of sound out of my monitors whenever the CPU was heavily loaded or I moved the mouse. It was just loud enough to be annoying but not bad enough to prompt me to really fix it.

My point wasn't to doubt how it sounded but rather the source. In my case I know it was RFI that was getting from the mobo, along a firewire cable, into my Firewire 410, from there into my monitors which had a known issue with poor RFI filtering. If I listened real carefully to them I could even hear the local TV station.


So have you tried any of my suggestions?

Bob.

Tried both your suggestions.

The isolator is a mains rocker switch located on the rear of the PC and directly below the mains input.

Grazie

"The isolator is a mains rocker switch located on the rear of the PC and directly below the mains input. "

Oh, OK, the power switch.

I'd be inclined to suspect the problem is the failure of one or more of the electrolytic capacitors on the mother board. You can read about this common problem here: http://en.wikipedia.org/wiki/Capacitor_plague

If that's what's happened and you don't want to buy a new mobo, CPU and RAM then any local electronics nerd could fix it for you pretty cheaply.

Bob.

Apart from scaring the shite out of me, on a purely visual inspection, don't think that that is it. Looks real nasty?

Gotta call out with the NLE PC builders for a get-back. We'll see. Maybe this IS the time to go more RAM and new MOBO et al?

Bugger........

Grazie

just get a bigger shotgun, bazooka, etc...

Have you added any software that may have changed the device drivers?
Have you tried isolating the sound sources from Windows? (Start Run sndvol.exe) Mute system sounds and any software that is there.
Do you have any "effects" turned on? (Sounds, Playback, Speaker Properties, Ehnancements)

1. I suggest you read through this old thread:

OT: ungrounded audio???

While it deals with hiss problems when the computer is on, many of the troubleshooting steps suggested by Spot and others may be relevant.

2. Unplug EVERYTHING from your computer except the keyboard monitor and mouse. Also, unplug the computer from the mains. If, with the computer off, the problem goes away, take the next step and plug the computer directly into the mains, bypassing your UPS/Filter. If the problem goes away, then you should suspect the UPS/Filter.

3. Even though you will find the following advice (from me) in the thread above, let me repeat here. With the computer turned on, open up your mixer panel and mute every single input (CD, Line Input, WAV, etc.) but keep the main output on. If necessary, click on the Properties button in the mixer and make sure that all devices are checked. Sometimes people don't enable the mixer to control all the devices. Do you still hear the hiss? You say it is really bad when the computer is on, so it should be easy to hear what is going on.

I think this is worth doing, even though, theoretically, the mixer only controls things while the computer is turned on. I have had a hiss that sounds very similar to what you are describing, and I've had it on more than one computer. In both cases it turned out to be a badly constructed CD-ROM (later a DVD player) which was connected internally to the sound card. Mutiing it temporarily cured the problem, and replacing the faulty device cured it completely.

Sounds ike the mobo is not being fully powered down, but is weird that not same in both channels. For hiss to come out is must be at least partially powered - grounding would more likely only produce hum or mains-related buzz.

May well be a bod mobo, caps or something else. Could well be the impetous for an upgrade ;-)

I'm about to embark on a new studio (mainly audio) PC mainly because I can't run enough Izo Nectar with my old Athlon2600+ !

geoff

" If I unplug the PC then the hiss slowly disappears, not in volume, but its presence. It's there until it is gone, if you know what I mean, takes about 6 seconds, hence my thoughts on a degraded grounding component, something like a capacitor that slowly discharges."

This is almost certainly an electrolytic capacitor that is "leaking" current between the layers (plates), probably in the analog portion of the integrated sound circuits of the MOBO. It should be a rather large (compared to other discrete components) capacitor.

Sometimes there are external indications of the failure, but this will probably take some audio signal tracing equipment. The real issue is whether can you get at the solder joints to test while the MOBO is powered...

It could be less expensive to buy a sound card than to go through the costs of testing and repair.

RalphM

You're chasing rainbows with the capacitor issue. When they fail, they fail catastrophically. Also, the bad cap issue is a couple of years ago, so the odds of finding one on a motherboard built in the past year are extremely unlikely.

Without hearing the noise it's hard to make any determination, but my money would be on a loose connection (or bad wire or connector) in the signal path. My backup bet would be on a device driver conflict.

Over many, many years of my technical career I have moved from being incessantly curious to just wanting to get the thing up so I can go back to my office and drink coffee. Though I have my own theories about the source of your problem, the end result is the same. As RalphM recommended, test with a plug-in sound card and use that until you replace the motherboard since it contains all the affected circuitry...
...with the possible exception of the audio cable that johnmeyer mentioned.
I haven't plugged a cable from an optical device into a sound card for a long time because I've seen how they snake through all the digital, noisey, hostile environment inside the PC.

Grazie, powered speakers?

Two separate solutions to this worked for me:

1) Try different mouse, Analog v USB -or-
2) Ground lift on powered speakers

Cheers,
Greg

You Guys are Champion! Really . . .

OK, there is presently NO solution.

Please imagine this:

1: A PC with nothing attached to it. NADA. Except for a POWER CORD and a set of Headphones plugged into the Audio Out of the MoBo's Audio.

2: There is a Power Switch on the Rear of the PC, which if left switched OFF nothing is heard.

3: When I Switch the Power Switch to ON I get this truly audible "hiss" coming into the headphones.

I realise I am repeating myself, but there aren't any loudspeakers connected; no devices of any sort; no monitors; no amplifiers; no cables other than the power cord AND the headphones.

I have moved the PC to an area away from anything in my studio.

I think I have answered all of your suggestions. I have read the thread John Meyer pointed me at and have done all the controls this non-meter wielding numpty can do.

I have yet to purchase a £20 cheapo sound card to test that theory, but even the Tech Guy from the PC World shop said he can't imagine that that would be a solution or even a control. Whatever is leaking to the ground would be doing the same across to the PCI slot too.

This is all very depressing.

. . . . . .

G . . . .

That there is a hiss also implies that that segment of the circuitry is at least partially powered. This itself may be a fault condition. Bad wires don't casue hiss. It could though pick up rf noise....

It is also unlikely that just one capacitor is faulty, if indeed that is a problem. Mobos are cheap - how many hours of one's time is it worth to chase rainbows ;-)

It is nigh on impossible for hiss out of one channel on an 'off' omputer to be a driver or Windows issue.

geoff

Hi Grazie, a long time ago in a previous life I was an electronics tech... haven't done it for many years and so I am really out of date. However, when things went kaput (back then when manuals were chisled into stone) the first thing to normally go in a gizmo was the power supply. The supply in a pc has multiple outputs at multiple voltages... but they are pretty cheap and pretty easy to swap. Hope you get on top of this soon. Good luck!

3: When I Switch the Power Switch to ON I get this truly audible "hiss" coming into the headphones.

When power switch is On, but PC is Off, the PSU still supplies 'standby power' to the motherboard, which enables functions like soft-start, wake-up on LAN, wake up on PCI event, etc. etc. to occur; many motherboards have a LED somewhere which shows stand-by power is active; presumably the soundcard section of your MB is also receiving some power, either by design or by fault.
There is a phenomenon known as 'whisker creep' where solder can creep across very close connections in some circumstances; could be that, or just bad manufacture, or come component failure ..... board-level diagnosis is very difficult on these crammed multi-layer boards.

My money is still on the failure of one or more of the electrolytic capacitors on the mobo. Something like 80% of the electronics that ends up as landfill has gotten there because of failure of those components. I've replaced a router that worked, sort of, and I'm pretty confident a failed cap is the cause of itdropping packets under load. Failure of these components is also a very common cause of problems in HDTVs. The manufacturers use cheap caps where they should have used "high ESR" capacitors. Over time the high current and temperature causes the component to fail and the failure is due to chemistry.

I'd again suggest giving your mobo a good visual inspection. Generally you can see that these components have failed, no need for anything other than a light and good eyes.

Fitting a sound card may well "cure" the problem. The sound card will have additional capacitors that'll filter the DC supply to the analog audio circuits. Problem I have with you doing this is the failed capacitor(s) on the mobo can also cause other subtle problems such as crashes under heavy load.

Bob.

i hate the smell of a popped cap in the morning....

seriously, have a sniff - it's a very unpleasant smell (if it's actually popped).*

always knew when one went on any of my betacam rigs since my nose was almost on top of it....

[edit] After I posted, I re-read Grazie's last post and realized most of what I'd written is covered by what he has already done. Hence, I've deleted most of my post here.

It sounds like you did exactly what I asked, namely you muted ALL of the inputs, as shown here:



and still had hiss.

"always knew when one went on any of my betacam rigs since my nose was almost on top of it.... "

If you think that's bad spare a thought for techs replacing a huge number of said caps in VCRs like the 500 digibeta deck. Sony supplied replacement caps and instructions but would not cover the labour which was quite considerable. I had thought the problem limited to just that deck but now searching through the remnants of a Sony repair centre I've found capacitor kits for a considerable range of Sony equipment. I'm not singling out Sony here, no doubt all manufacturers wer caught out by those cheap but inherently defective capacitors.

I should point out though that that problem is different to what is now happening with manufacturers using under spec'ed components. The problem is so significant its been covered in the popular current affairs programs. The worst thing is failures of caps can lead to very unusual problems. Panasonic have a HDTV that will loose the ability to receive certain TV stations and the problem is caused by a DC filter capacitor failure. What compunds the problem is these components generally last for the duration of the warranty period, generally beyond even the extent of an extended warranty of 3 years.

Bob.