Something everyone should know about sound cards.

CarComp · 12-17-2002, 02:49 PM

I learned recently, from installing a few more computer systems into people's cars, that sound cards DO NOT truly put out the same kind of power that a normal head unit does. True, it is close, and does work, but I have found that you can reduce a lot of "electrical noise" that the computer / car generates if you follow these few guidlines.

1. Ground your soundcard to your car's ground. Also ground your cdrom casing to the car's ground.

2. Use a ground loop isolator between your sound card and your amplifiers (readily obtainable from Radio Shack). Keep it away from any power / speaker wires, because it WILL pick up noise. The isolator removes any power supply induced hiss / noise.

3. Invest in a good Pre Amp. Audio Control makes a good one called The OVERDRIVE that can match your output from your sound card.

4. In conjunction with the Pre Amp, set your amplifier gains to their minimal settings, then set your computer volume at 3/4 max. Begin turning up your amplifier gains until you hear clipping / distortion.

5. In Windows: Mute all un-needed volume controls. Usually the mic, the modem, and any others that you do not use.

That should get rid of the noise.

12-17-2002, 03:09 PM

instead of going with a pre-amp, could you just run the soundcards output into the aux input on an aftermarket CD player and get the same effect? or does this not prevent the problem of not putting out a much power as just a HU by itself?

magnetik · 12-17-2002, 04:51 PM

Carcomp, I agree with all your statements EXCEPT that of the ground loop isolator.... I find them to distort/ruin sound output and is really more of a 'cure' than a 'prevention'

follwing your other steps, if you still have noise problems I would be looking at the quality of the sound card itself....

SuperMatty · 12-17-2002, 10:08 PM

I disagree with the set software volume to 3/4. That is an arbitrary value that has no basis or reason. Mine is turned to 100% and I have no noise except at my highest 1/10 of my head unit volume.

CarComp · 12-18-2002, 05:56 AM

Those values were assuming that you have no head unit installed. If I use full volume on my puter, I get a nasty case of clipping. Not distortion, but I lose the quit a bit of my mids.

jol · 12-18-2002, 09:11 AM

In Sweden, we user triple-shielded cables, guess there's plenty for everyone

t0ffluss · 12-18-2002, 09:19 AM

Quote:

Originally posted by jol
In Sweden, we user triple-shielded cables, guess there's plenty for everyone

Hear hear

hehe

(In Norway too)

Richard

Michael Szilagyi · 12-19-2002, 09:02 AM

I have a sound blaster live and it has loads of voltage on the outputs. More than most stock headunits. I have the gains on my amps set to about 1/4 to 1/2 if i remember correctly.

mike

Cliff · 12-19-2002, 09:00 PM

I agree about the Ground Loop Isolator...it takes away from the overall sound (does a good job at taking hiss away) and takes most of all bass tones. I took mine out and the difference was HUGE, so I started putting up with the hiss again. Then again, Im running off of an inverter, so as soon as OPUS's new PS comes out that should solve alot of the hiss problem...

Also, I also found that turning my windows volume up to 100% really starts to distort the higher frequencies...I turn it down to about 85% and it sounds best. But this is with the integrated sound in a Via Epia 800 im using...so that could be the problem too. Getting an audigy soon, that and a good ol DC-DC should do it! =)

magnetik · 12-19-2002, 09:45 PM

good to see someone else had the same experences with Ground Loop Isolators....

Cliff, once u get your Audigy you will notice the difference.... im running an inverter with my Audigy and it sound fantastic... going DC-DC in the new year with a EPIA 800 (keeping the Audigy of course!) so all should be supa sweet...

12-19-2002, 10:29 PM

what are good brand power invertors? I will need to be getting one soon, the power supply ill have on the computer is 300watts, so would it be good to get a power intertor rated at 400watts?

magnetik · 12-19-2002, 10:39 PM

common mis-conception......

a 300W PSU does NOT mean it will draw 300W, but can handle upto 300W of load...

for example I have a 300W PSU and only a 140W inverter running in my setup of a Duron 800Mhz/40GB HDD/5.6Inch TFT.... thus the mp3car setup obviously draws less than 140W and ALOT less than 300W

good brand of inverters?? wouldnt know..... I got mine from www.jaycar.com.au in Australia, but thats prob a little use to you!

Cliff · 12-19-2002, 10:49 PM

I have a Jensen 300w which my alternator doesn't like at all, I think it's giving it a beating...

Jensen are usually what people go with. They are good inverters.

Mag: Cool. Im looking forward to the audigy. I just have to find a pci riser slot for the mobo first though, you will need one too when you get your epia..

stinkynathan · 12-20-2002, 04:59 PM

Quote:

Originally posted by CarComp
4. In conjunction with the Pre Amp, set your amplifier gains to their minimal settings, then set your computer volume at 3/4 max. Begin turning up your amplifier gains until you hear clipping / distortion.

a very, VERY good gain-setting tutorial is here. Also has some other install links and info. they guy is definately a different character, but he knows his audio and electronics...

later,
nathan

bstanton · 12-20-2002, 06:40 PM

my carputer draws 130watts continious (no floppy / dvdrom) off my 180watt power supply unit, and my 140watt Radio Shack inverter (300watt surge) works fanastic.