I have a problem that I have been dealing with with several vehicles for years, but in my OBW it is the worst. I have the AM/FM, Casette, 6 disk CD changer spliced into a hi to low converter going to a kenwood preamp 7 channel EQ going to three aftermarket amps. I have installed stereos for years, and have Alt Snd Suppressors on all of the units seperately to match there amp ratings. As long as I have the lights off I do not hear any whine, but as soon as I turn my parking lights on, the whine comes into the system greatly, and increases to a level that is fairly painful to the ears when the headlights are on.

I have good grounds on all pieces, run my power directly from the battery, same size wires on input and gnd, and have not messed with power wires on the factory head unit.

This has resulted in not being able to listen to music after dark, or turning the boost off the EQ and turning the volume all the way up to hear anything, which starts crackling my speakers!

:madder: It is definately alternator whine as it changes pitch with RPM.

I would appriciate any suggestions or thoughts on this matter, I have noticed throughout the years headlights increased the whine, of course due to the additional amprage draw, but I am going deaf with this one. My all nights trips are not easy to make without music to get me through late at night.

I first must say that I have very little experience dealing with noisy car audio, but I do have experience dealing with noisy power supplies in general.

 

I assume your noise suppressors are chokes. A capacitor between the inductor (choke) and the load will increase the strength of the low pass effect on the power rail. You may need to experiment with different value caps, larger capacitors target lower frequencies. Beware of inrush current, an empty cap looks like a short to ground when the power is first turned on. I don't know if this will work, but sometimes a Pi filter works well for filtering both the power and ground to a piece of equipment. A Pi filter is basically a common-mode choke with a cap on either side.

 

Make sure your battery has a relatively low series resistance. The battery is a filter for alternator noise. Series resistance in the battery will increase the system voltage swings as a function of charge/discharge current. EDIT: I must add here that excessive resistance elsewhere in the system might add to noise, so battery cables and other connections must be checked.

 

You might try another alternator as well. Your current alternator is probably overloaded.

 

I don't know how your grounds are laid out, you might try a star configuration.

 

Electrical noise, audible and otherwise, is a black art. Some experimentation is always necessary.

Had the same problem...when i'd hit the gas the sound would get louder.

 

 

I bought a new CD/MP3 headunit and the harness to put it in...and BANG...sounds perfect.

 

 

 

Hope that helps

If your running some serious stereo equipment, why not run a dual battery setup and a stiffening cap?

Seems like when you load up the system you get the whine, i have it too, but i suspect the factory ground for the head unit is the culprit in my case, i just need time to re-ground the thing.

 

Double check that all your grounds are REAL good too.

Noise suppressors in my opinion just hide a problem with your electrical system.

 

I would even consider taking the car to an auto elec that has an interest in car audio and have them do a good check up on your elec system.

 

Is your alternator in good shape?

I've got a couple of these in my car:

 

http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=265-047

 

Mine are an older model, but they work as advertised.