#6Fan

I am trying to replace my factory door subs with some Rock Fosgate Punch Stage 2s and need some help. The factory sub has 4 wires going to it (2+ and 2-). My S2s only have two connections (1+ and 1-). Should I connect both factory +/-s together to their respective S2 single terminal or should I bridge somewhere?

Help Please

RRRoamer

You have a problem. The factory speaker is a dual voice coil sub driven by two (each) amps. While it is pretty easy to drive multiple speakers with a single amp channel, it is a lot trickier to drive a single voice coil with muiltiple amp channels. Magic smoke tends to be released, either very quickly or eventually if everything isn't perfect.

That leaves you with two choices: Only use one of the amp channels to drive the sub or get a speaker that has dual voice coils.

Also, be aware that the factory sub is rated at 1.2 Ohms per voice coil. Most aftermarket speakers come in 2, 4, or 8 ohms per coil (assuming multiple voice coils) configurations.

It's not quite as bad as it seems. When I replaced the factory subs in my car with JL Audio 8W3V2s, I measured the resistance of the factory coils (not the impedence, but the actual resistance) and it came in at a measured 1.6 ohms. That is a LOT higher than I would expect for a voice coil rated at 1.2 ohms. Basically, the impedence should be the resistance plus what ever additional impedence is added by the capacitance (low) and inductance (VERY HIGH) of the voice coil. So if I am measuring 1.6 ohms resistance, then the actual impedence MUST be greater than 1.6 ohms.

The voice coils on my 8W3V2s measured out at 1.8 ohms resistance (in the ball park of what i would expect for a 2 ohm speaker), so the actual difference is pretty small.

Sonic Thunder

Do what I did and buy an aftermarket amp to push your Rockfords.

dreem363

I bought the Fosgate 8" stage 2 subs and they did not fit in the doors, the magnet was too deep and I had to return them. Have you tried to see if they fit? You might need to find some woofers with less depth. How are you going to install them?

BatNastard

RRRoamer, thanks for clarifying that. Can we call those factory jobs "2 ohm subs" since that designation is only nominal for any driver anyway?

I tried bridging one channel to no adverse (or positive) effect. The way I understand it, if an amp is not bridgeable, both negative channels are in phase w/ each other, so there would be no difference whatsoever. I'm sure there is some potential for harm, I just can't think of why

Sonic Thunder

Installing Rockfords are easy as long as know a little about fiberglass.

#6Fan

Does anyone know what kind of watts the factory amps for the door subs are pushing out?

svt boost

do those JL's drop in?

Sonic Thunder

I believe they (doors) have to modified as well.

BatNastard

A few educated guesses...the factory subs say "120 Watts Max." so let's assume it's less than that RMS. The "500" designation is peak power, the system might do 200-250W RMS. The head unit probably does no more than 60W continuous into 4 channels, but maybe they rated it for 100W, leaving us with 100-150W for the sub amps. Each one would do 50 or 75, each channel doing 25 to 37.5. Remember this is into 2 ohms or less.

Infinity

I was able to get 53 watts clean from mine (measured with a clamp-on ammeter and using my own ears for distortion levels).

BatNastard

Wow...I'm honestly surprised my estimate was that close :P Good on yer for finding that out! How many volume bars was that?

Infinity

That part I didn't check, I knew I was only half-doing it. I got so caught up in listening that I didn't look. I wonder if the amps are well-made to the point where their outputs are fairly equal?