# 2 amps one sub



## NJPCRX (Jul 25, 2012)

I have an old CV Stoker 18 with duel 4ohm coils. I also have 2 us amps usa-400's. Soooooo, i was thinking of running both of the amps bridged one on each coil. These amps arent strapable. So can I just set the gains the same and call it a day? I see alot of mixed opinions on this. What do you guys think? I know I could run one amp, but I think it would be more power this way and the amps could run easier at 4ohms.


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## ATOMICTECH62 (Jan 24, 2009)

Yes,absolutely.
You will have to make sure the controls are set as closely to each other as possible.
The crossover frequencies are very important.If they are not exactly the same there will be a phase shift and a lose in output.


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## todj (Dec 11, 2008)

I was told to never run two amps to two separate coils. Even though they are the same "model" amplifier they don't always produce exactly the same amount of power. Age, usage and input power could all play a roll in the equation. This results in uneven power and ultimately subwoofer failure. I don't have first hand experience but that is what I was told.


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## ATOMICTECH62 (Jan 24, 2009)

It is really no different then running a 4 channel amp with dual power supplies bridged into 2 channel mode.


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## smgreen20 (Oct 13, 2006)

Set gains with a DMM to match and you'll be fine. Done it myself a few times, never had any issues.


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## NJPCRX (Jul 25, 2012)

The amps have no crossovers built in. so would i run one set of rca's from the deck and split them at the amps. Then the deck would control them as one amp as far as crossover point, right? How else would you do it? Wouldn't splitting the rca's also cut the voltage in half from the deck? How else would I be able to set it up? Do old external crossovers have provisions for running multiple amps from a single sorce?


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## Changchung (Aug 15, 2012)

You have to be sure that both amps is in MONO, put left and right RCA to each amp then connect the amp in bridge to the sub.

I will recomend you do this before connect to amps to the sub

How to Set Your Amplifier Gain to RMS Power Using Ohm's Law - YouTube


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## NJPCRX (Jul 25, 2012)

so how should I run the rca's. split them, get a preamp or external crossover...


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## NJPCRX (Jul 25, 2012)

so how do I run the rca's? Can I split them by means of a preamp or external crossover or strait from the headunit and split them at the amps? To set the gains with a DMM, I need to know the 4ohm bridged rating on these amps. I'm having trouble finding that. Also, how do you set the gains with a DMM on these old amps when they are so under rated? Do you just use the rated power for your equation?


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## todj (Dec 11, 2008)

I would look into purchasing a line driver.


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## GLN305 (Nov 2, 2007)

NJPCRX said:


> so how should I run the rca's. split them, get a preamp or external crossover...


Just use Y-cables


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## Changchung (Aug 15, 2012)

NJPCRX said:


> so how do I run the rca's? Can I split them by means of a preamp or external crossover or strait from the headunit and split them at the amps? To set the gains with a DMM, I need to know the 4ohm bridged rating on these amps. I'm having trouble finding that. Also, how do you set the gains with a DMM on these old amps when they are so under rated? Do you just use the rated power for your equation?


I think that you amp have crossover, this is yours?

http://www.reaudio.com/documents/collection[2001].pdf

For the rca, you can run it from the HU, to avoid phase problems, left/right from the HU to the amp, use two Y, one Y to left of each amp, the other Y to each right of both amp and then connect there the rca from the HU, for adjust the output follow the steps show in the video below...


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## NJPCRX (Jul 25, 2012)

ok, i think i get it. So the line driver would be for boosting the preamp signal from the head unit since it will be split between the 2 amps resulting in like a 2v signal? I was worried about that. Maybe an eq/line driver like the soundstream digi q? I had one of those and it sucked. I need to look into a better quality one. Any suggestions??


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## benny (Apr 7, 2008)

GLN305 said:


> Just use Y-cables


This.


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## minbari (Mar 3, 2011)

GLN305 said:


> Just use Y-cables


x3.

most RCA outputs are 300-600 ohm output and most amplfiier inputs are 10-20k ohm input. you can put ALOT of amplfiier inputs on an output and not load it down.


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## NJPCRX (Jul 25, 2012)

if you guys think a line driver is in order, then which one would you recommend? a dash mount eq line driver?


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## ATOMICTECH62 (Jan 24, 2009)

minbari said:


> x3.
> 
> most RCA outputs are 300-600 ohm output and most amplfiier inputs are 10-20k ohm input. you can put ALOT of amplfiier inputs on an output and not load it down.


X4
You will not need a line driver.Most amps have an input impedance 20-100 times that of the deck.
Once again its the same thing as running a 4 channel amp bridged into 2 channels.Some will have a switch that connects the 2 pairs of rca's internally and for the ones that dont,simply use a Y adaptor.


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