Terrible noise from audio output of my pc104.

I purchase two PC104. The first with VIA Eden 600 and the second with Intel 
Celeron 400.
You can see specs at http://www.seco.it/old/schede_prod/M585-HTE01A.htm.

I installed XP. This cards don't have headphone output but only speaker 
output (4 pins L+,L-,R+,R-). I've tryed to connect a headphone plugging 
together two -. It works fine, the audio has good quality bur there is a 
strong noise. (Also with two separated speakers...)

I try to low all volume (Speaker, modem,...) and the situation goes better 
but not ok.

All this with Via Eden. With Celeron the noise is terrible.

Do you have any suggestion to decrease the noise. (The sellers suggest me to 
put a condenser (2200) between +5v and ground).

Thanks,
The Storyteller.

MGM Systems wrote:

> I installed XP. This cards don't have headphone output but only speaker
> output (4 pins L+,L-,R+,R-). I've tryed to connect a headphone plugging

Look at the power pin(s) on the audio amplifier. If there is noise at
this point, you should filter it _there_ and not after it has already
been amplified!

audio amplifier???
This card is a maze!!

"larwe" <zwsdotcom@gmail.com> ha scritto nel messaggio 
news:1160142419.599757.216300@m73g2000cwd.googlegroups.com...
>
> MGM Systems wrote:
>
>> I installed XP. This cards don't have headphone output but only speaker
>> output (4 pins L+,L-,R+,R-). I've tryed to connect a headphone plugging
>
> Look at the power pin(s) on the audio amplifier. If there is noise at
> this point, you should filter it _there_ and not after it has already
> been amplified!
> 

"MGM Systems" <mgm@mgm.it> wrote in message 
news:yDnVg.14894$pp1.10935@tornado.fastwebnet.it...
>I purchase two PC104. The first with VIA Eden 600 and the second with 
>Intel Celeron 400.
> You can see specs at 
> http://www.seco.it/old/schede_prod/M585-HTE01A.htm.
>
> I installed XP. This cards don't have headphone output but only 
> speaker output (4 pins L+,L-,R+,R-). I've tryed to connect a headphone 
> plugging together two -. It works fine, the audio has good quality bur 
> there is a strong noise. (Also with two separated speakers...)
>
> I try to low all volume (Speaker, modem,...) and the situation goes 
> better but not ok.
>
> All this with Via Eden. With Celeron the noise is terrible.
>
> Do you have any suggestion to decrease the noise. (The sellers suggest 
> me to put a condenser (2200) between +5v and ground).

Do you have the line in and microphone inputs enabled in the volume 
control? That can cause some noise to get through to the output.

I doubt the capacitor will do much for you because there will be lots of 
them between 5V and ground already for decoupling the devices.

You need to have a look at the audio amplifier as Lewin suggests, which 
is painful but worth it. 

MGM Systems wrote:
> audio amplifier???
> This card is a maze!!

It should still be easy to locate. Many of these cards use the NS
"Boomer" IC. Look around the place where audio egresses the board.