Car stereo: noise problem (long) (1 Viewer)

[DavidY]

Here's my install history on a 1996 Mazda B3000 4x2 Cab Plus, Automatic:

1. Installer (MECP) replaced stock with new Alpine HU, new Boston Acoustics front speakers, a used Orion 4 channel amp (2 for the front, 2 bridged for sub), a used 12" SVS sub in a new sealed enclosure and new 4 ga. wiring. After I noticed noise, installer puts in ground loop eliminator. It fixes the noise problem.

2. The same installer puts in a Compustar remote starter/alarm/2 way paging system and a 1 farad cap (used) and a pair of a/d/s 5.25 mids (new). Noise is apparent in the front speakers. Installer spends a day checking over the entire system by switching components. Noise problem is still there. Installer blames noise on used Orion amp. He further adds that the cap makes the noise more apparent.

What should I do? The noise is apparent during quiet passages. I am not 100% satisfied with the above, but am not sure if I can do anything about it. Not really mad but am disappointed.

Possible solutions:

1. If it's the amp, I should be able to switch it with the installer's amps and the noise should disappear...right?

2. Take off the cap. I don't think that I really need one since my system has limited power and I am a SQ guy.

Others?

Thanks in advance.

Dave


------------------
HU: Alpine CDA-7873
Fronts: Boston Acoustics RX-87 5x7 coaxials
Rears: a/d/s 235is 5.25 mids
Amp: Orion CS200.4
Sub: 12" SVS in a 0.75 cube sealed enclosure
Cap: 1 Farad Lightning Audio Strike
Dampening: Brown Bread
Wiring: 4 gauge Knukonceptz

 

[Philip_G]

you def. shouldn't need a 1 farad cap for that amp (200 watts?) but I can't imagine it's causing the problem, what kind of noise is it? is it alternator noise? (kinda whining, but increases pitch when the engine revs) or something else?

 

[DavidY]

The reason why I have a 1 farad cap in my system is that it was cheap, too good to pass up. In the future, I am planning to add a sub amp, 400-600 WRMS or possibly more. I don't think that it's alternator noise as the noise is there when I'm idling....but I will check this out.

Dave

 

[Philip_G]

I've been able to hear it at idle before, find a cd with a big break of silence and crank it up, rev the engine and see what it does.
I'd say a better amp might be the way to go.

 

[David-S]

Like he said, if it's a high whining noise that increases in volume w/ your revs, it's probably "alternator noise"... you can look at fixing it with
a) better ground points - make sure all your components are grounded to solid metal (no paint etc)
b) making sure your power wire isn't run next to (especially parallel to) your RCA signal wires..
1) yes
2) i've never heard of a cap causing noise...
again, what type of noise is it?

 

[Henry Carmona]

David has great advice!

Also, if the ground wire is too long, that could also introduce noise. Try to keep it under 12 inches if possible.

 

[DonnyD]

Soem great advice above and I will add: 1.Check your wiring harness around your head unit especially your pre-out connections and routing. 2: Adjust your gains on the amp as your HU signal and amp input may not be matched. 3: Change one thing at a time until the culprit is found.

Loose grounds and power wires too close to rca cables are usually a good place to start.

 

[jeff lam]

Is there noise with the car off (on ACC)? I had alternator noise/whine and solved it with a isolator. Maybe your alternator just doesn't put out enough amps of current for all your components. Go to RS and get the device that goes in your PWR line, has a blue, red and black lead. Red goes to Bat, blue to any small component (eq, head unit, or x-over, Black to ground. It helped a lot. I forget what it's called though.
Found it. Look here:
http://www.radioshack.com/product.as...%5Fid=27%2D055

 

[Wayne Murphy]

Spark plug wires can give off some nasty noise. I had the regular Honda wires and switched to the high performance Canadian Tire brand. The high pitched whine drove me nuts so I returned them. The Ground Loop Isolator only works for so long. It absorbs with small capacitors (I believe) and they eventually fry. I had two in my old car/system.
Otherwise check the signal path and see if it crosses any electrical wires and see if you can get extra shielding.

Even if the Orion is causing the problem you won't hear the whine due to the cutoff for the subs.

 

[Todd Hochard]

Sounds like a ground issue to me.

It may help to run a big ground (10 or 8 ga) from the point where the amps/HU are currently grounded, straight back to the BAT- terminal.

Todd