Auto Amp install stupid question...

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jaetee

Member (SA)
Okay, so I have the benz's dash completely disassembled as I'm in the process of putting in a new one that does not have cracks. I'm also taking advantage of this opportunity and just wired the harness for my car stereo. I am also installing an amp in the trunk for a subwoofer and have a question I'd like to run by some of you...

The Amp is an old sony that has a 12V pos, a ground and a remote cable (aside of the RCA in's and the speaker conections).

I have the ground terminating to the same ground on the car as the head unit (per suggestions by install manual) and I have the amp remote wired to the harness properly...

Where is the best place for me to hook up the amp's 12V positive?

My first thought is to use the same constant 12V that my stereo uses, but that would require a splice and is a really thin cable... Instead, I'm inclined to run it straight to the battery instead. And maybe hook a fuse in there as well. But, would the alternator create noise? Or, do I need one of the noise canceller-thingy's too?

Thoughts, suggestions?

:-D
 

monchito

Boomus Fidelis
jt sometimes on the fuse block there might be a unused space were you might be able to make a short cable to the block use a fuse and feed the stereo :-)
 

oldskool69

Moderator
Staff member
Directly to the battery will surely bring noise. Most newer alternators have a counter for this but given your vehicles age, probably not. You could purchase an inline noise filter but you risk sound quality with some of these devices as well...
 

ahardb0dy

Member (SA)
Don''t connect the amp to the constant on the radio it is not a large enough gauge to power an amplifier, the amp should be hooked directly to the battery, the size of the amp or if you have more than one amp would determine the wire gauge. I would say for one small to medium sized amp (wattage not physical size) 8 gauge would be fine, I am running my 2 PPI amps (200 x2 & 75x2,50x2) off of a 4 gauge power cable fused near the battery which should always be done and fused near the amp,if the amp has built in fuse you don't need to add a separate one near the amp.

I always try to make the ground wire as short as possible in my case it is attached to the inner fender in the trunk, just make sure you scrape any paint off the spot where the ground will go. I would not hook the ground to the radio ground. I've never had noise problems hooking the ground up near the amplifiers.

Decent amps usually won't have noise problems it's usually when you get into those cheap "1000 watt" flea market off brand amps where problems occur.

one other thing if the head unit is an aftermarket unit with a CD make sure the remote turn on wire is connected to the turn on wire coming off the radio harness and not the power antenna wire as some head units when you switch from radio to CD the power antenna wire looses power
 

Master Z

Member (SA)
Straight to the battery with the fattest power cable u can buy, fit. Definitely put an inline fuse as to not fry your amp/amps fuse if a short occurs.
I agree with Tony, run the shortest ground. with the amp well grounded you should not get any noises from the alt.
I always put the remote on a different circuit than the radio, maybe wipers or dome lights, something thats always on.

Another tip that is cost effective, depending on the watts you're pushing, is running a capacitor inline.
If your sub is gonna slam and hit the low notes for any extended periods of time, like with hip hop or electronic music, your amp will fall short of recreating the frequencies and the bass will roll off and your driving lights and dash will probably dim to the rhythm, making your alternator work harder than it should to keep the juice flowing.
You will definitely hear and feel a difference while running a cap.

If your gonna be running an amp for the lows, Don't neglect the highs in your system, run an amp for them too! :cool:
 
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