What amp for 2 Rockford Fosgate subs

[DavoX7]

Looking at 2 Rockford Fosgate 8" subs for my parcel shelf, 50-200wrms 4ohm dual voice coil.

What would be the best amp? Do i need a two channel to wire them seperatley or a mono block and running on the same output. Im a little confused with the ohms and dropping when running two on the one amp? Anyone know what im talking about??

Thanks :thumbsup:
-Dave

 

[Shaneus]

When you run speakers in your case subs in series, it will halve the resistance (ohms) causing the two 4 ohm subs to become 2ohm. This will allow more power to pass through them and in turn making them louder. That is my basic understanding I'm sure one of the tech heads here will give the the correct rundown.

To run them in series just connect the + of one sub to the - of the other, then the remaining terminals to the corresponding outputs on the amp.

ie.

(-)SUB 1(+)---(-)SUB 2(+)
I____ (-) AMP (+)_____I

 

[shaggerz]

When you run speakers in your case subs in series, it will halve the resistance (ohms) causing the two 4 ohm subs to become 2ohm. This will allow more power to pass through them and in turn making them louder. That is my basic understanding I'm sure one of the tech heads here will give the the correct rundown.

To run them in series just connect the + of one sub to the - of the other, then the remaining terminals to the corresponding outputs on the amp.

ie.

(-)SUB 1(+)---(-)SUB 2(+)
I____ (-) AMP (+)_____I

You've got that backwards... series connection will add their impedances, and parallel will split them.

If you have two four ohm subs and connect them in parallel (that is... the positive lead of each sub connects to the positive terminal of the amp and the negative lead of each goes to the negative of the amp) then the impedance as far as the amp is concerned will be 2 ohms. Make sure that the amp is capable of driving a 2 ohm load or you could potentially damage it, or at best, it could cut out or not work at all.

 

[DavoX7]

Ok thanks, makes sense.

So i can run 2 x 4ohm subs parallel to a mono block as long as it can handle 2ohms.

 

[shaggerz]

sure can

 

[DavoX7]

Awesome. Thanks for your help mate.

 

[Joe Peeps]

Looking at 2 Rockford Fosgate 8" subs for my parcel shelf, 50-200wrms 4ohm dual voice coil

The subs are 4 ohm DVC - if you wire all the coils up in parallel you will be providing a 1 ohm load - not good unless you wanna pay for an amp which is 1 ohm stable.

If you only manage to get an amp that is only two ohm stable, you will be forced to wire your woofers at 4 ohm. This can be done by wiring in parallel between woofers, and in series between coils (wiring in series between woofers is not advised due to the potential noise created by background emf)

Conversely, you can pick up a 2 channel amp and run one woofer per channel at 2 ohms.

If youd like give us a budget and we can recommend some amps to consider

 

[shaggerz]

DAMMIT I missed the word "dual"... that changes the rules completely!

+1 for Joe Peeps

 

[DANNY8]

I thought when u wire up subs in a series, the + from the amp goes to the + on the first sub, then from that to the other + on the other sub, and same for the -? Like all the +'s are connected, and all the -'s.

I had a JL 4ohm amp, and 2 JL 8ohm subs and that's how I was told to do it...is that right or wrong?

 

[Joe Peeps]

Thanks Shaggerz, easy to miss that going by the other posts

VHPirie -

series connection will add their impedances, and parallel will split them.

you had it wired up correct for your application, only the nomenclanture is wrong. That wiring is parallel wiring
Series wiring would be from amp + to sub 1 +, sub 1 - to sub 2 +, sub 2 - to amp -. This has the effect of adding all the ohms, so if you did wire in series youd be showing the amp 16ohms with your 2 JLs.