I am kinda new to this I had my sub in my truck but I didn't have it bridged at the amp. Now I am wondering if I have to rewire the sub to hook it up to the amp bridged. The sub itself has 4 places to put wires and it is a JVC 12in Warren G addtion that I got used from a kid at work. I don't have any of the papers so no luck there.

 

subscribing to thread.....

 

How is it wired up now?

4 places to put wires, Im assuming you mean DVC (It has 2 positives, and 2 negative, correct?
And, after looking at that sub, it looks like its only available in 4 ohm DVC versions, so FIRST off, is your amp stable at 2 ohm bridged? If not (not a whole lot are, mostly higher end amps) then you will have to wire it for 8 ohm, and only get half the power that amp puts out when its bridged.

If thats the case, you arent going to gain any power by running it at 8 ohms bridged, compared to one voice coil on each channel at 4 ohm, which is the way it sounds like you have it wired up right now.

Anyway, to wire the sub, you will need to connect one of the positives, to the negative of the other voice coil. Then the remaining positive nad negative go to the possitive and negative of the amp.
That will give you 8 ohm.

IF you amp is stable to 2 ohm bridged, then you can wire boths positives to the possitive of the amp, and both negatives to the negative of the amp. You will get 2 ohm then.

What is the amp?

 

well bartak if you dont mind helping me too....

ive got a 4ish year old JBL 1200.1 amp, and have two infinity 12s (lower end model something like 700 peak 350 normal) and currently have one wired in as rear in/out and one as sub in/out. How do i bridge it? I dont mind having both run on sub in/out.

the other thing, is the subs are both single voice.....

 

Patman, 1200.1 is a mono sub amp...so its not bridgable.

The two sets of RCA inputs throw a lot of people off.

This is the reason for the two sets:
If you have a CD player with only front and rear outputs, and NO sub output, then your bass would 'fade' depending on where you set the fader if you only had the front or rear RCA's to the amp. With the JBL BP amps, you can run a set of RCA's from your HUs front outputs to the JBLs front RCA inputs, and a set of RCA's from the HUs rear ouputs to the JBLs rear inputs. This will stop the sub from 'fading' whenever you use the fader on the HU.

Now, it sounds like your HU has a sub output, so all you need to to is run one set of RCAs from your sub outs to EITHER the front OR rear inputs on the amp. You do not have to have signal to both of them (front and rear inputs).

Even if you dont have sub outs, all you need is one set of RCA's to the front or rear inputs, and you are fine as long as you dont fade the HU, or dont care that if you fade the HU from front to back that it will make the sub louder or quieter depending on where the fader is.


Hopefully you can understand this

 

yah, so just need to unplug a the set running off the rear, do i need to unplug the one from the back of the HU or can i leave it?

edit: also would it be okay to run just one sub off of the amp? like i said i think rms is 350-375, and peak of 700-750

 

If your HU's sub outputs are connected to the font inputs on the amp, then yes, you can disconnect the rear RCAs.
I would disconnect them from the rear of the HU and just pull the whole RCA cord out, and just have the sub RCAs in there. But if you arent wanting to do that, just dissconnect the rear and tape over them.
You might have to reset the gains...


What ohm are those subs? 4 ohm probably? You can run one, your going to be giving it about double its RMS wattage though. If the subs are SVC 8 ohm though you are fine.
That amp is 1200WRMS at 1 OR 2 ohm, and 600 watts at 4 ohm.
So, like I said, if your subs are SVC 4 ohm, then you are sending them about double thier rated wattage. (peak power means nothing at all)
Just something to think about.

 

I dont know for sure what rating they are, but i think they are 4ohm, they are pretty basic infinity subs, im just lookin to crank up volume of bass without turning up gain, and without tuneing amp up really high on the sub output.

Do i still need to tape them off i leave them floating in the truck (undo at HU and undo at amp)? They are under the carpet, and dont really want to pull seats again for a set of RCAs

 

Before you go and tell me how crappy it is, I know it is but I only paid $40 for everything and that is what I could afford. Anyways the Amp is a SPL Series IV XL-820 or something like that. It says 2 ohm stable for stereo and 4 ohm stable for mono. It says bridgable at 4 ohms for 460 Watts.
Another thing I already have it set up for 2 ohm, both the positives are wired together and both the negatives are wired together on the sub.

 

so you have a 4 ohm stable amp and a 2 ohm sub

the only thing to do is wire up the sup in stereo to the amp. with each voice coil going to a seperate channel

 

well i tried it with Sub output only, running only one sub, and it was quiter

And now its running two on just ths sub output and sounds a little better, and as loud as it was before.

and it tried doing it every combination i could like
..+-
+-..
+..-
.-+.

the . s are the unused terminals when i connected only one sub

 

Pat, you dont need to tape them off if you unhook them from the HU.

Yes it will be quieter, thats why I said above yo might have to reset your gains
You will need to turn the gain up. Its ok though, because you reduced the voltage going to the amp.
Say your HU has 2 volt pre outs. With your rears and sub out connected, your amp is seeing 4 volts from your HU. Now, with just your sub output connected, the amp is only seeing 2 volt. So to compensate, you need to turn up the gain. Its ok though, thats what the gain is for, to match the HU voltage to the amp.
Use a DMM to set your gains so you dont blow the heck out of those...Even with the gains set correctly I would be worried about overpowering those subs...

Its doesnt matter what + and - you wire it to on the amps terminals; both positive and negative are connected inside the amp. There are just two of them so you can easily run bigger speaker wire, instead of trying to cram two 10 gauge wired into one terminal.

Desk, like styx said, you can either wire each VC to a channel on the amp OR you can take the sub out, wire it for 8 ohm, and bridge it on the amp. You wont gain any power though. You would only gain a true mono signal...