Stereo Amp Install Help

[Dream240]

100x4 MAX @ 2ohms, 50x4 RMS @ 4 ohms 4-channel amp: Currently running it on 16 gauge power/ground wire, 4-channel RCAs, factory speaker out wires from factory amp location.


Okay I've been doing some searching and found out that so far, the stock wiring in an S14 SE with the factory amp is inadequate for really any amp upgrade. Here's what I've found so far:

Power wire running from battery straight to amp(in trunk, on hump) = 10 gauge (or better)
Remote power wire from head unit to amp = 16 gauge (or better)
Ground wire for amp - as short as possible = 10 gauge (or better)
Speaker wire outputs from amp = 18 gauge (or better)

Also I've decided to run brand new wiring from my amp to all 4 speakers since the factory wiring is old and seems to be to small (24 gauge?) for what I'm wanting to do.

Now my only concern is whether to use the high level inputs or low level inputs on the amp. Since my head unit has both the standard speaker outputs (high level) and pre-amp outputs (low level), which should I use? And really what's the difference? Also what happens when you use both?

Can anyone answer these questions? Or give me any more advice on the install? Mainly because I'm trying to reduce the buzzing. And I've already separated the power wires from the RCAs and got a good ground. I'm leaning towards installing the noise suppressors I've got but don't they reduce power output from the head unit to the amp? Resulting in lower sound performance?

Thanks guys.

[Clearalbino]

Do you have a stereo model so i can look it up?

[S14DB]

Use the Low Level(pre amp) lines. The High Level go thru the head units amp so the quality decreases.

If the battery is in the front and the amp in the rear I would run 4ga to the back to a block and then a 8ga supply to the amp and a 8ga ground.

I would use 16ga if not 14ga for the speaker wire. 18ga is kinda bare minimum. A long run from back to front is going to need a bigger gauge.

[180sx_Drifter]

^+1 do what he says. Couldnt have said it any better

[druthafoo]

Definitely only use the low levels.

As for your wiring, use the biggest possible. Heck all of my wiring before my distro block uses 1/0 but you don't need that. 4 gauge should be enough.

[Dream240]

Use the Low Level(pre amp) lines. The High Level go thru the head units amp so the quality decreases.

If the battery is in the front and the amp in the rear I would run 4ga to the back to a block and then a 8ga supply to the amp and a 8ga ground.

I would use 16ga if not 14ga for the speaker wire. 18ga is kinda bare minimum. A long run from back to front is going to need a bigger gauge.

Great thanks.

You bring up another interest concept, so running through the low levels completely bypasses the head unit's internal amp (hence the term"pre-amp")? So the only power my speakers will get is the power coming from the amp (50x4 RMS watts)? Or will the speakers get both the amp wattage AND the stereo wattage? Is there a way to combine the two sources of power so that each speaker is getting about 75 watts RMS?

I always thought the amp just boosts the head unit wattage by as much as it's rated. Set me straight guys.

[projectRDM]

I disagree a bit. For speaker wiring, bigger isn't always better. Larger gauge wire is typically more stranded, though it can handle more current there's also more resistance across it. For a +12V signal like the power or ground leads that's not a big deal, but a fluctuating low voltage signal like the speaker output needs as little resistance as possible. The signal will suffer through using larger gauge wire unless it's solid core or light stranded. The OE wiring, being just that, is more than enough and is already prerun for you. Why not use it? Unless you're going to be putting several hundred watts to each speaker you will never see the benefits of going bigger.

[projectRDM]

Great thanks.

You bring up another interest concept, so running through the low levels completely bypasses the head unit's internal amp (hence the term"pre-amp")? So the only power my speakers will get is the power coming from the amp (50x4 RMS watts)? Or will the speakers get both the amp wattage AND the stereo wattage? Is there a way to combine the two sources of power so that each speaker is getting about 75 watts RMS?

I always thought the amp just boosts the head unit wattage by as much as it's rated. Set me straight guys.

Incorrect, it's either or. You use the internal amplifier, or the external amplifier. Not both. High level inputs are stepped down inside the amp anyway, not 'doubled up'.

[Dream240]

Incorrect, it's either or. You use the internal amplifier, or the external amplifier. Not both. High level inputs are stepped down inside the amp anyway, not 'doubled up'.

So why is it that when you have an amp hooked up, it sounds so much louder than without one? The difference is only about 25-30 watts RMS (in my case). Is it maybe that the external amp is just designed more efficiently?

And the only reason I'm leaning toward running new speaker wire is cause I think I've got damage to some of them somewhere, RF speaker volume is really low and I can hear things like opening the doors and pushing the brake pedal in my speakers, speakers make like clicking and popping sounds.

[druthafoo]

It doesn't necessarily sound louder but much cleaner. The increased power allows you to run a much cleaner signal to the speakers. When you amp speakers you allow a cleaner signal to come through. When people try to crank their speakers without an amp it sounds distorted because the signal is clipping due to a limited range. The amp increases that range. Crap this makes no sense but imma leave it up so someone can correct me.

That clicking noises and such could occur because of a ground loop.

[Dream240]

Nah you pretty much nailed it. Makes sense. Plus I guess another benefit is the gains on an amp as opposed to 6only your EQ settings on your head unit.

I've been trying to find a ground problem to no avail. I'll keep looking.

[projectRDM]

Good answer, but there's more to it than that. I worked in car audio for over a dozen years and saw a lot of stuff come through with all sorts of ratings, you can't believe the hype all the time.

Basically it goes like this, a head unit can be rated for any given power level possible, IE with 18 volts input, 20% distortion, and only between 2k-10k Hz. It's how manufacturers can sell a product that will never do what it says, sort of like "your car will do 180MPH, downhill in a snowstorm with a hurricane pushing it". There's no way possible for it to ever be in those circumstances, but they'd never sell anything if it was marked 2.3 watts RMS per channel. The most extreme, in fact impossible cases, are where the claims come from.
For amplifiers, the ratings are typically much more realistic, 50 watts of power is measured with 12.6 volts input, from 20-20k Hz, at the very least .01% THD. So in reality your 30x4 head unit may only give you 4 watts a channel at best, if you're lucky. And honestly, look at a good 50x4 amplifier, how big is it? Now look at the same 50x4 head unit, and factor in a tuner and CD mechanism. There's just no way possible the internal amplifier can even remotely be any bigger than half the case.

[Dream240]

Ahhh....that makes sense Russ. Thanks.

Wait...what do you mean they can't fit a 400 watt amp in my head unit...???? My specs clearly state 100x4 PEAK!!! That's B.S. :p

Thanks for the input, I'm sure this helped more people than just me.

[druthafoo]

Just watch out, alot of companies rate their amps at 14.4 v instead of the more realistic 12.2 v. I know JL and the lesser known companies try to list their amps at the 12.2 v rating. The bigger companies use the 14.4 v ratings to try and attract more buyers.