4 Channel amp, different impedances?

[EddyBigShoes]

Not sure if this is possible but can you run say a 4 channel amp with 2 channels going in stereo to the front speakers at 4 ohms and the other two channels bridged for two subs in series running at 2ohms?

Otherwise is it bad to have two subs running in stereo?

I'm asking because I would rather have one amp running everything than having to buy two, 2 channel amps.

[Au2low]

Yeah, thats fine, you can do that with the front speakers, just left right i take it?

Also, you can't "bridge" the other to channels into stereo, when you bridge two channels it becomes a mono signal. you can run two subs from it, but if you where to connect two subs in series you could give yourself a 8ohm load, you would need to do it in paralel too get it into a 2ohm load. it also depends on the type of amp you have, many amps are 2ohm stable, but not in bridge mode. if you just ran the L/R outputs and not bridge them you could go down to ohms.

that help you at all?

[Kinks]

Impedances don't have to match. As long as you don't go under the minimum impedance specified for that amp.

Having stereo bass is supposed to be a good idea in home theatre applications. What I would do is run separate terminal jacks for each sub, or get one of the "dual" terminal plates with 4 connectors (2 for each channel) because it'll be easier to parallel the subs (use the metal tabs provided!) or series them (short length of speaker cable) depending on what you want. Then try em both ways and see which one sounds better.

[EddyBigShoes]

Thanks guys I didn't know if 'series' was double the ohmage or half. I must have got them mixed up.

Also, I meant in stereo as not being bridged but just from the left and right channel independantly as an alternative if I couldn't run the two subs in parallel and at 2ohms.

To clarify is parallel,
(amp)
| |
+ -
(Sub 1)
+ -
| |
+ -
(Sub 2)

and is series?
(amp)
|
+
(sub 1)
-
|
+
(sub 2)- (back to amp)

Hope that lines up.....

[Au2low]

yeah, something like that!

Parrallel
+> ----+----+SUB1->|
| |
| |
| |
->------|------------|---|
| |
| |
| |
| |
| |
+--SUB2->|

Series,
AMP +>-------- +SUB1- -------- +SUB2---->back to amp -

[Au2low]

DANM! I just spend 10mins doing that and it did not come out!!!

parallel, just connect both subs + - to amp

Series, is as above!

[EddyBigShoes]

Yeah thats a bummer but thanks, I get the gist of it.

[VT Calais]

If you want to have both of the subs @ 2R with the amps channels bridged, the amp must be 1R stable.

[tandy ass]

Originally posted by Au2low
DANM! I just spend 10mins doing that and it did not come out!!!

parallel, just connect both subs + - to amp

Series, is as above!

Just hit the "QUOTE" button at the bottom right of your drawing and it will appear fine.

[Au2low]

Shutup bus stop boy! :)

[Boxer]

Originally posted by EddyBigShoes
the other two channels bridged for two subs in series running at 2ohms?

.

err can you clarify what you mean there?

How are you getting two subs connected in series to 2ohm? (i.e. they would have to be 2 ohm ea with the amp bridged to acheive a total load of 2 ohm)

[teK]

1ohm subs? :wtf: If they were 2R each, in series total load would be 4R.

I think he has 2 4R subs, wants to run them in parallel for a total load of 2R, bridged across his rear two channels. In this case yes the amp has to be 1R stable. I had a shitty old amp when I started out and I ran 2 4R 6x9s in parallel across it's two channels since I wanted mono rear fill. It was hot but not untouchable, but eventually burnt out after 6 months or so.

[Cplus]

Originally posted by EddyBigShoes
Thanks guys I didn't know if 'series' was double the ohmage or half. I must have got them mixed up.

Calculating resistance is easy.


For Series;

Total Resistance, Rt = R1+R2+......+Rn

For Parallel;

1/Rt = 1/R1+1/R2+........+1/Rn

So as you see it's not Half, it just works out that way when you are using to subs of the same resistance.

And when you bridge two channels, each channel sees half of that load. Be carefull this catches people out sometimes.

To run to 4ohm subs in parallel and bridged over two channels your amp must be 1ohm stable.

Tek - your amp survived for longer than 10 minutes with your 6x9's because it's their nominal resistance that is 4ohm. Most of the time it would be higher than that.

Look up some resistance curves of subs, you'll see what I mean. Plenty of subs out their rated at 4ohm have double or more than that when used in the 30-80hz range.