Mach amp, Fosgate P1S4-8 sub, unsatisfied

[UrbanRedneckKid]

I just finished installing a Rockford Fosgate 8" sub in my OEM enclosure. It seems to me like I had more bass with my blown stock sub, the sound quality is much better at lower volumes.

I left the OEM stuffing in the box, and I stuffed the whole front side of the box, attempting to get it closer to the recommended box volume.

I am assuming it's this way because the sub is under-powered. Is there an amp that fits the original spot, that is 400w max/ 200w rms @4ohms mono?

 

[Anime]

Rockford Fosgate P1S48
Punch Stage 1 8" 4-ohm subwoofer

•8" 4-ohm subwoofer
•molded polypropylene woofer cone with poly-foam surround
•16-gauge steel bend frame
•power range: 50-150 watts RMS (300 watts peak power)
•frequency response: 40-250 Hz
•sensitivity: 84 dB
•top-mount depth: 4-1/8"
•sealed box volume: 0.2-0.3 cubic feet
•ported box volume: 0.65 cubic feet
•warranty: 1 year

Going by those specs, a 200W amp would be too much.

The Rockford Fosgate Prime R125-2 is a 2-channel amp that's spec'd for 125W RMS when bridged to one channel at 4 ohms, should be perfect, costs $65 on Amazon, free shipping.

http://www.amazon.com/Rockford-Fosgate-R125-2-2-Channel-Amplifier/dp/B007BG5NLW

It's also fairly compact at only 8 in x 8 in.

There are lots of other lower-power 2 channel amps that will put out the 100-150W the sub needs when bridged, but they will all be about the same price, or more.


The fill actually makes the sub act like it's in a larger enclosure. The factory enclosure is already way bigger than the 0.2-0.3 cubic feet the sub needs for a sealed enclosure. You could always port it, though, or just see how the sub performs with the new amp, then try it without the fill and see if it sounds better.

 

[UrbanRedneckKid]

Those were the specs I used to choose this sub to use with the stock amp. Upon receiving it I learned it was different. The manual says 200w rms/ 400w peak. Though all the box volume specs are the same.

I stuffed the front of my box, by cramming it full of Styrofoam, packed super tight. I might change it, thinking about cutting the box and epoxying it together smaller.

I went ahead and ordered the said amp already today on my lunch, along with a spool of 4g wire, and a speaker level RCA converter.

BTW what turns the amp on? I'm pretty sure I only saw 4 wires in the plug. Assuming power, ground, speaker+, and speaker-. No remote...? I searched for it, but found nothing.

***amp purchased was a Rockford Fosgate P200.2

 

[Anime]

Sometimes companies just "update" specs when testing reveals they can get away with bumping up the power handling numbers. I would say long-term, it'd be better to power it with 125-150W if you want it to last. You can push it with 200-225W, and it might take it, but it also might eventually blow. Depends on what you're after. You'll get harder hitting bass with 200W+ for sure, but 125-150W would still bump, just a few dB less overall.

No need to cut the box, just epoxy in a plastic panel to block off the front part if you want to try making the box volume smaller.

A speaker-level RCA converter? You're sticking with the stock head unit? Why not spend money on a quality aftermarket HU to go with your sub/amp setup?

Not all amps require a remote wire, "smart" amplifiers just turn on when they receive an input signal via the audio inputs.

 

[UrbanRedneckKid]

So it should be fine if I don't crank the gain...

That sounds much easier, and I won't lose any mounts and create rattles.

I like the stock headunit. It's pretty good quality, has everything I need, and I spent hours fixing the display. I do plan to add a RCA jack in place of the cassette deck later. And it matches the dash, and isn't flashy, I'll be less likely to have me window busted and my stuff stolen.

It did more looking and found the converters with a remote output, think I'll just run a wire up front to the stereo harness.

 

[Anime]

Gain doesn't affect watts, you're still driving it with the max wattage all the time with a 200W amp, assuming it puts out it's rated output, or more.

The problem with stock head units is distortion, they typically have 1-10% THD (Total Harmonic Distortion), where aftermarket head units have 1% or less, sometimes much, much less. That distortion is another thing that kills speakers, a clean signal with lots of power behind it is less likely to damage a speaker than a signal with lots of distortion and average power behind it. You can guess how bad a signal with lots of distortion and lots of power behind it is.

There's nothing wrong with keeping the stock head unit if that's your preference, I would just have suggested you go with an amp that has speaker-level imputs and sticking with 125-150W.

 

[UrbanRedneckKid]

So... Would a 4 channel amp, and speaker upgrades take care of the distortion issues?

That is what I was planning on doing next. I'm only doing the sub first because I blew it up.

 

[Anime]

Maybe, depends on the amp. Amps don't usually filter out distortion in the original signal though.

The right line output converter will help though, if you use it right and tweak it so the amp is getting a lower level input signal.

You can use a 2-channel converter for the sub amp, then if you decide to get a 4-channel amp and new speakers, get a 4-channel converter for that, and you can have aftermarket everything else, but with the factory head unit.