im ordering a sub and amp setup for my bro for his going off to college gift haha im going to get two Alpine Type-R 12" subs, 2-ohm DVCs, and wire them in regular old parrallel mono form... and bridge the channels of either a Rockford 300s or 400s.

the 300s is 300x1 bridged at 4 ohms rms
the 400s is 400x1 bridged at 4 ohms rms
and the wiring of the 2ohm dvc subs should give me a 2 ohm load on the amp... now wouldnt a 2ohm load mean double the 4 ohm load? so id really be pushing 600 watts out of the 300s and 800 out of the 400s?

i think that the 300s should be enough to push both of the alpines right? or is the ohmage and stuff wrong and i need a bigger amp? the alpines are 300 watts rms

thanks so much for the help :lala:

oh yea.. what do you think the settup would sound right once i found the right amp? rather have nice loud clean rumbling bass in the car, not looking for everyone for miles to hear us coming lol

 

Sounds like you're going to put a strain on that amp- unless it's an older Rockford, and can handle it.

Correct me if I'm wrong, but you're buying two subs, and each sub will have a dual voice coil, of which, each voice coil is 2 ohms? If you bridge each sub, you turn each sub into a 1 ohm load. (Two 2ohm voice coils in parallel = one 1 ohm load).

You said the 300 (or 400) is 300x1 bridged at 4 ohms rms. If you wire the subs in series (+ of one to the - of the other), yeah, you'll be throwing a 2 ohm load at the amp, and yeah, you'd get 600 watts out of the 300s and 800 out of the 400s. BUT, make sure the amp is rated for that!

Typically when you bridge an amp, you're dividing the ohms in half again. I don't know the specs of the amp your'e talking about, and I"m too lazy to go search for it, so I'll come up with an example amp.

Example amp:
two channels @ 4 ohms rms (two channels @ 2 ohms)
bridged to one @ 4 ohms rms

When you grab that bridged spec @4, you're making each channel become "two channels @ 2 ohms rms", and combined, you get "bridged @ 4 ohms". That's why amps usually say (at 2 ohms) in parenthesis after each channel.

To run a 2 ohm load off the bridged @ 4, you make each channel run at 1 ohm. So now it's "two channels @ 1 ohm rms", combining for a "bridged @ 2 ohms". Can each channel really handle a 1 ohm load?

Someone correct me if I'm wrong, it's been a while since I've done any multiple bridging!

 

Okay, I nabbed a Rockford Punch 300s's specs off of Crutchfield. This is a new amp, eh? It might not be able to handle the kind of loads that the Rockfords could 5 years ago.

.......
The Punch 300S is packed with cutting-edge Rockford Fosgate technology (blah blah blah)

Key Features:

stereo, bridged mono or Tri-Way output
75 watts RMS x 2 at 4 ohms
150 watts RMS x 2 at 2 ohms <---

300 watts RMS x 1 at 4 ohms in bridged mode
.......

Notice the 150x2 at 2 ohms! Wire that in series (aka "bridge the amp"), and you get your 300 wattsx1 at 4 ohms. See? It doesn't claim to be one ohm stable.

When you hook up one 4 ohm sub (single voice coil) to the amp, each channel sees a 2 ohm load.

When you hook up one 2 ohm sub (two 4 ohm coils wired in parallel), each channel sees a 1 ohm load. This is similar to what I think you wanted to do- make each sub a 1 ohm load (parallel the DVC's), and wire the subs in series, resulting in the "equivilant" of one 2 ohm sub.

For this amp to do what you want, you'd want specs like:
75 watts RMS x 2 at 4 ohms
150 watts RMS x 2 at 2 ohms
300 watts RMS x 2 at 1 ohm <--- this isn't a real spec, but it would be here for a one ohm stable amp


What would I recommend? Buying one sub, single voice coil. Get the Rockford 400S, a MTX Thunder 8000 12" sub, and a box for the sub. And don't forget to buy quality power cables and patch cords for the system! My buddy works in car audio, and he's made amazing bass out of one 10" sub and one amp. I think your brother would be thrilled! 'Fact, I bet this will be "too loud" for you, so you'll have to run it with the amp gain turned down. Might as well get the 300S then, and save a few bux! (It'll still be loud, and you'll still have to turn it down!)

As another downer, I ran a Rockford 60.2 bridged with a 2 ohm load. The amp wasn't one ohm stable... but it worked for a long time. 'Fact, it worked great, except it'd shut off every now and then. So I put two fans over it... and one hot day, "SNAP!" Want to see a pic? I've bought the MOSFET, and will replace it... one day... when I have time.... (sigh) but you can bet I won't over power that amp any more! Yep, the circuit board looks black because it's burnt...

 

ah i screwed it all up, i did the wrong math and thought that by wiring the 2 ohm DVC's in parrallel i would get 4ohms a sub... i was wrong lol but... what would happen if i got the 4 ohm DVC version of these subs? then each channelw ould be getting 2 ohms each as u said i think... but i dont want it to look like that picture! maybe ill reconsider on a few things before deciding lol thanks for the help

oh yea, this is a new amp, whats the lowest these things can handle in ohmage? i know the oldschool ones were really quality amps but the new ones kinda cut corners or sumthin. so should i be wiring this thing in series? well i remember rockford used to have the wiring wizard on their website, and that had so many different wiring diagrams it was amazing... but now i cant find it on their page so im lost unless u know of any other pages that offer diagrams and info like they did. thanks a lot for the help though...

maybe i will get a single 12 like you said with a nice amp, more decisions... just dont want it to be too too loud and have all boom and no sound... dont wanna be like one of those lil druggie kids with the 100% boom boom bass and no other sound from highs or vocals in music lol

:lala:

 

aahh i found the rockford wiring wizard diagram on their page so that will help me a lil

 

With these models of Rockfords, you have to go by the ratings as advertised. And if you don't want a booming setup, why go for mutiple subwoofers? Like I said you can make one sub sound pretty damn loud, you should consider getting a smaller amp. Amps have gains on them, so you can turn them down... and if there's too much boom, it's an excuse to buy a 4 channel amp and 4 new "normal" speakers. You'd probably be fine with a 100 watt amp and one 10" sub in a sealed box.