ARGH! Engine noise!!

JayKaye · 04-23-2004, 12:44 PM

Hi all,

I have quite a bit of engine noise and i have NO idea why. I spent 5 hours today trying to resolve it but to no avail.
First up. I have all my power cables running up the left side of my car and all the RCA and speaker cables running up the right side of my car. The only speaker cable which crosses (doesnt run along it very much) a power cable (only the power for the CarPC) is the cable going from the soundcard to the input behind the Equaliser (EQ). I suspect that the dodgy 'headphone' jack used on the soundcard output could be part of my problem, but it doesnt accomodate for so much engine noise I am getting!

I am not running any filters in my setup (and dont want to either), however I havnt run a filter in any of my setups before and I have managed to get away with zero engine noise (most decent amps have filters built in anyways).

Any help would be greatly appreciated.

JayKaye · 04-23-2004, 10:18 PM

um, any help please?

Pogi · 04-24-2004, 02:43 AM

What are you using to power the PC???? It COULD be that if ur using a power inverter. It could be causing problems. Also what guage is ur Power and Ground????? ur ground shoule be AT LEAST eaqual, or more then ur power cable. you seem to know what ur doing (power to one side, RCA's to the other) but you know to ground to BARE THICK metal, Something like a Seatbelt bolt with the paint ground away.

Do you have any neons? also, does the Engine noise change pitch with the RPM of the car??????? it also could be ur headphone jack, what kind of sound card are you using? Is it embeded???? I would try to find something with RCA outputs. Ive hard problems with headphone to RCA converters, It never sounded right.

djmickyg · 04-24-2004, 02:54 AM

yeah check ur ground... and make sure its good..

another thing could be the condesors on ur distributer could be gone..
these filter the noise from the spark plug system from ur car..

amps have filters in em but the noise could be geting generated b4 it hits the amp.. so its just amplifing the noise... the amp filters filter its power not the noise in the music going in..

Dr Jeckyl · 04-24-2004, 03:54 AM

1) ground your negatives as close to their respective devices as possible (if you have electronics in the truck, ground them to the trunk. If they're under the seat, ground them under the seat) don't carry your negative power all the way back to the battery.

2) many noises can be choked out by simply wrapping a sound wire through a magnetic core 5 or 6 times.

3) if you have a strong suspiscion on your headphone jack, remove it and solder a gold plated jack onto it (they're only about 5 or 6 bucks at Radio Shack)

4) what year is your vehicle? Many pre-90's models have RFI chokes near the coil or distributor. It looks like a 'c' size battery painted aluminum with one wire coming out the end. Replacing this may help.

JayKaye · 04-24-2004, 05:27 AM

Thanks for the tips.

The car PC is running off a PSU I built myself, not an inverter. The CarPC is grounded (including the case) to the 12mm bolt holding in the seat using thicker cable than the power cable (just in-case), HOWEVER, I havent filed away any paint, ill check that tonight.
My car is a 1992 model, and I cant seem to find a 'C' size battery looking thing anywhere.

I did a small test on the setup I have and the noise seems to be coming through the power cables, not the sound cables. Ill make sure everything is grounded properly tonight and let you know how it went.

Thanks for the advice

starfox · 04-27-2004, 04:58 AM

If checking your grounds doesn't help, here's some other ideas:

Does your amplifier ground your RCA input shields, and are the two shields (between right and left on your amp) continuous? If they are, you might have a ground loop which is picking up engine noise. Try pulling our your RCAs so the tip is touching but the shield is disconnected. If you have less noise like that, you might have to make your own RCA leads with a common ground.

JayKaye · 04-29-2004, 02:53 AM

ok guys, i spent quite a bit of time on the car today and this is what ive discovered.

1. Grounding the RCA shielding did nothing to the plethora of engine noise I am getting.
2. Disconnecting or making the grounding cable thicker coming from the CarPC chasis does nothing.
3. Installing a ground isolator loop thingy to the cable going from the CarPC to the Equalizer makes matters worse, I get a terrible hissing noise ontop of the engine noise.
4. I put a filter on the power line of the 4 channel amplifier. I thought maybe the noise is coming through the power cable. Again, no glory here either.
5. I tried unplugging the RCA's going into the AMP and only having the signal bit of the RCA plugged in (as mentioned above), no difference here, still go engine noise.

Now, whilst driving my car I noticed that the engine noise was considerably louder when the RCAs from the Equaliser were closer to the Car PSU (both behind my dash). I concluded that I am getting the noise from the 16gauge wire and/or the Car PSU that is behind my dash and around ~15cm away from my equaliser (which has 4 pairs of RCA's in it. Sub pair, Rear spkr pair, Front spkr pair and Car PC input pair). I removed the equalizer from its home and tried running it as far away as possible from the PSU/cable but unfortunately the sound got a LITTLE better, but not much.

JayKaye · 04-29-2004, 02:56 AM

noone likes a LOOONG post, so here is the rest..... continued....
-----

I currently have all my power cabling (CarPC, both AMPs etc..) running along the left side of my car which is the side my ECU (or EFI computer) is on. I have all my RCA's and front speaker wiring running along the right side of my car. I have fairly thick grounding cable although I guess it wouldnt hurt to be thicker. I doubt its my grounding cable though as the engine noise I am getting now I didnt used to get back when my equaliser was behind my front seat (temporarily) before I built its permanent bracket for the dash. I am almost certain the noise is coming from the RCAs in the dash (EQ).

any help? ideas?

gubon13 · 04-29-2004, 03:46 AM

What kind of EQ are you using? If it's one of those 1/2 din thingies, then there you go. I ONCE bought one to try and help a friend amplify his audio out from his headunit and it went right back to the store 1/2 hour later. I read up on them online and they're pretty much all crappy. If you have a good quality EQ, then I think it's less likely the EQ.

Curiosity · 04-29-2004, 04:00 AM

Have you tried bypassing the EQ? Process of elimination!

JayKaye · 04-29-2004, 10:21 PM

Ill give bypassing the EQ a shot, will let you all know how it went.

Mears · 06-01-2004, 11:24 PM

What happened with this?

antimatter · 06-01-2004, 11:36 PM

I guess that was the problem. Ungrateful thread starter. Not enough decency to update his own thread with.

shame shame

JayKaye · 06-03-2004, 07:03 AM

oops! sorry guys. I only realised i left this thread open when I checked my 'suscribed threads'

Turns out the problem was a combination of a few issues listed below:

1) the PSU I made for the CarPC was too close to the RCA inputs for the EQ. Moving the PSU further back, along with rewiring the 4g wiring I have running behind the dash, reduced the engine noise to almost zero in the front speakers but the rear speakers were still giving me some grief.

2) the rear speakers were running off cheap-o RCA's, I removed these and the fronts work perfect with little to no noise. I have still yet to replace the RCA cable with a decent low-noise one (like the one running my front speakers).

Hope this helps

oh, also. Just wanna add that I rewired my speaker (inc. RCA's) and power cables to seperate sides of the car with the spkr cables running on the side of the car that the ECU wasnt on. This helps too