Thread: Need help building VW Monsoon amp input

Originally Posted by Zip-Lock

From what I've read it sounds like the Monsoon really wants that balanced input.

It's balanced but biased to 6V. I think when you say "balanced" most people think 0V on both lines is the normal state with positive and negative swings (on both lines of course) for signal.. I believe the monsoon wants 6V on both lines as the normal state with 0 to 12V swings on both lines as signal.

Originally Posted by Zip-Lock

Anyone know an EE who's up for a design challenge? Mp3Car can front the development costs and make a product out of it.

I'll ask around.

So when are you guys getting this noise? Ive been playing with my input and not getting any noise, both from my cd player and laptop. have yet to try it with the MII 10000...

Do you have the noise with the engine on and off?

My 5V supply is from a 12V line the M1-ATX PSU. My audio source is the M10000

I have noise both with engine on and off, so I'm pretty sure it's the motherboard or the PSU. It's also not a constant hum, but some variable static and some whine. I'll try another souce tonight and see what happens. If that fixes it then it's clear the sound card is the culprit and maybe a ground loop isolator would help (as long as I inject the 5V after the isolator on the monsoon side).

Originally Posted by kbyrd

My 5V supply is from a 12V line the M1-ATX PSU. My audio source is the M10000

I have noise both with engine on and off, so I'm pretty sure it's the motherboard or the PSU. It's also not a constant hum, but some variable static and some whine. I'll try another souce tonight and see what happens. If that fixes it then it's clear the sound card is the culprit and maybe a ground loop isolator would help (as long as I inject the 5V after the isolator on the monsoon side).

Hmm, i have to try it tonight with the MI10000 and M1-ATX, i was using 12V from the 12V socket in the back...

Ill let you guys know what i find.

I just tested with the following:
- 12V from PSU molex thru regulator for 5V.
- audio from a battery powered portable radio.

Still heard the noise. I'm almost sure it's in time with hard drive access or something. So either my audio run is picking up interference along it's run or the 5V is noise. I would have tested 12V from the car rather than the PSU, but I broke my output connection on my regulator circuit (flimsy solid copper wire).

I have "cleaned" my 5v line so it is noise-free and when I use my battery powered radio, i get absolutely no noise! But, with the clean line and carPC soundcard, the noise is back!

ZipLock:
I already came up with a schematic for the balanced input from a soundcard.
Here is the schematic:

I just haven't had time to try it, so if anyone is willing that would be awesome. PM or email me or reply if anyone has questions. This would be great for everyone if it worked.

Are you sure its not a ground problem with the M10000. I have a MII12000 and i had noise like crazy when my video out cable was unplugged. I ruled it as bad ground on the audio port to the motherboard. When my video was plugged in the noise went away. I just attached a ground wire to the chassis of the Carputer and my truck to fix the ground issue.

Just my 2 cents. Other then that your schematics look good. Hope this helps.

Originally Posted by pRoFiT

Are you sure its not a ground problem with the M10000. I have a MII12000 and i had noise like crazy when my video out cable was unplugged. I ruled it as bad ground on the audio port to the motherboard. When my video was plugged in the noise went away. I just attached a ground wire to the chassis of the Carputer and my truck to fix the ground issue.

Just my 2 cents. Other then that your schematics look good. Hope this helps.

That does sound like a cause of the problem, since the 5V injector is obviusly working correct since you get no noise with the radio.

Because if it was a problem with the injector it would sound bad even with the radio...

Originally Posted by alimh

I have "cleaned" my 5v line so it is noise-free and when I use my battery powered radio, i get absolutely no noise!

How did you "clean" your 5V line?