Connecting two amplifiers

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Wiring two amps together???

Hello all -

I have a sub in the back of my car and was just given two identical amps.

Is there anyway to connect the two amps together to make one higher output amp? I think the answer is no, since it really doesn't make any sense, but maybe someone has done it ....

-David
 
Yeah its called bridging. You connect the positive output of one amp (call it amp number 1) to the positive input of the speaker and the positive output of the other amp (call it amp number 2) to the negative input of the speaker and you leave the ground terminals on both the amps unconnectted ... you then feed amp number 1 directly and you invert the same signal and feed this inverted signal to amp number 2.

This will have the effect of allowing each amp to drive half the actual load so each amp produces twice the power that it normally would. Therefore, the speaker will now see 4 times power of a single amp.

Just a warning, make sure the amps are capable of driving half the load of the speaker. ie. if it is a 4ohm sub make sure the amps can drive 2ohms each or the outputs of the amps may die.
 
Basically, the grounds of the two amps have to be the same, and therefore by implication have to be tied to vehicle battery ground. Check with an ohmmeter whether the speaker ground on the amp is the same as power ground.
p.s. Grey, he did say they were identical...;)
 
I should have given you guys more specfics (not to downplay anything you have said, just for my own benefit).

I have two, identical, bridgeable, two channel amps that are stable at 1 ohm. So I have two pairs of speaker outputs per amp. Which positive speaker output do I connect to the sub? Also, I have one dual voice coil sub (4 ohms per coil). Isn't what you are saying the exact same thing as connecting one amp to each coil? Isn't that a bad thing to do since any variation in the amps/signal will cause the voice coils to fight eachother instead of cooperate? Would your suggestion work perfectly for a single voice coil sub? It seems like it would, so it should also work perfectly for a dual voice coil sub if I have the coils wired in parallel or series (mine are in parallel for a 2 ohms load).

When you say invert, does that mean just take the preamp RCA connection from my head unit, split it with a Y, connect a pair correctly to amp 1, and flip the connections on the other pair to amp 2? I didn't think that would make a difference since I only have one sub so it's mono, but it seems like that would change the phase 180 degrees. If I connect one amp per coil, will I also have to invert the signal on one of the amps?

Why do you have to invert the signal anyway?

What are "topologoes"

Thanks
David
 
dih1118 said:
I have two, identical, bridgeable, two channel amps that are stable at 1 ohm. So I have two pairs of speaker outputs per amp. Which positive speaker output do I connect to the sub? Also, I have one dual voice coil sub (4 ohms per coil). Isn't what you are saying the exact same thing as connecting one amp to each coil?
...
Why do you have to invert the signal anyway?
...
What are "topologoes"

My goodness.
If your amps are already bridgeable, they have an inverter built in somewhere. The inverter changes the polarity of one of the signals so that the speaker can be driven from two outputs - one output will be exactly opposite the other (in a non-bridged setup, one side of the speaker will be fixed at 0). You get twice the voltage, see. You use the two channel's positive outputs, one to each side of the sub's voice coil.
Because your sub has two coils, and each amp is bridgeable, you can use both channels (each amp bridged to make effectively one channel) of both amps to drive the sub. If you feed both amps with the same signal, the signals won't be 'fighting' one another.
I don't know about topologoes, but by topology Grey was referring to the circuit used in the amp. With some circuits, you can't bridge two channels (for example, circuits that already inherently use bridging).
The manuals that came with the amp and sub should explain this as well. I strongly suggest you read them carefully before starting to wire this up.
 
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