Poor man's guide to remove power supply noise from audio

**Rob Withey** · 01-22-2007, 11:39 AM

The transformers don't filter out the noise. They isolate the grounds.
If it was a case of filtering, a simple high pass RC filter would do the trick.

**spuzzdawg** · 02-04-2007, 09:54 AM

Don't know how I forgot it worked by isolating the grounds by the time I got to the end of the thread - thanks for correcting me. A lil OT Rob Withey but how did you get the neat little pop up table for your car specs?

Spuzzdawg

**RedGTiVR6** · 02-04-2007, 10:31 AM

Spuzzdawg -

http://www.mp3car.com/vbulletin/announcements/93477-carpc-specs-in-the-user-profile.html#post987518

In the forum announcements.

**bosstone74** · 02-06-2007, 04:31 PM

I just grounded my motherboard to the chasis of the car...and it was gone

**raxy** · 02-07-2007, 03:06 AM

Originally Posted by spuzzdawg

I might be making a big assumption but I would have thought that the interference noise had a relationship to the RPM of the engine, in which case the telephony bandwidth is almost perfect - I guess it could go a little higher

Spuzzdawg

Transformer limited bandwidth means bass end treble will be substracted from your music, this by no means is expected

**Virus3000** · 02-15-2007, 06:50 PM

Thanks, will try this

**jasbirriyat** · 09-11-2007, 08:56 AM

well, i had the same problem with my car pc. i just added a ferrite ring on the RC cable. gave about 3 -4 round around the ring. and the ferrite ring is for about 0.5 usd i think.

**Snortonnorton** · 09-20-2007, 04:41 PM

very impressive that you can build your own.

but a good working GLI is 15 bucks at circuit city made by Tsunami in the car audio section, and it's more durable so I don't have to worry when I shoved it behind my dash.

**BiG K** · 09-21-2007, 02:53 PM

How about this for a poor mans solution to interence??

I bougth a USB creative soundblaster Live, works great etc. But if my phone is near it, with the sound high, it can get alot of interference. So I started experimenting.
I chucked it into a large anti-static bag and hey presto, approx 50% of mobile phone interference gone!

Plastic is not the best thing to wrap things up in and besides, 50% is still quite annoying!

So I wrapped it up in foil.....normal everyday kitchen aluminium foil. Worked a treat, by my reckoning, approx 95% of inteference gone!!

I am willing to bet if I put two layers and grounded the foil, I could possibly get 99% if not possibly 100%??

If it works for mobile phone inteference, could possibly work for other types of inteference??

Since this is a cheap simple way of cutting inteference, maybe someone could put it to use and let us know??

Also, why stop at the sound card? Why not enclose the PSU and/or computer in this manner??

The only problem I can see, with it being aluminium, it conducts electricty, so you have to be VERY careful not to short anything out!

Also could be a tricky issue with vents etc??