SUB Pre-Out Question

[sushi2hot4u]

Hi everyone. First off thanks for viewing the post and feedback in advance..

Now whats been puzzling me. I have pioneer pioneer gm-d7400m Monoblock Amplifier and Sony 1300watt subwoofer. The amp has L+R Pre-Out RCA input.

On the back of my headunit, I have 3 RCA inputs: Front L+R Pre out , Rear L+R Pre out and single SUB Pre out.

What is the single SUB Pre out at the back of the headunit for? Is it for an active subwoofer?

Should I match and connect L+R pre-out on my amp to L+R (front or rear) at the back of the headunit?

Sorry if ive confused anyone.

[DRFVDR]

the sub pre out is so that the amp driving a subwoofer can be controlled by the head unit,the head unit will have settings for "loudness" and frequency that will only come out of the subwoofer pre outs

[Scoobydoo]

It's a mono signal, as opposed to the front & rear, left and right stereo signals. Use the subwoofer pre-out.

Subwoofers do not particularly like a stereo signal.

[sushi2hot4u]

 Scoobydoo said:

It's a mono signal, as opposed to the front & rear, left and right stereo signals. Use the subwoofer pre-out.

Subwoofers do not particularly like a stereo signal.

So since there is only single sub pre out as opposed to L+R pre out on amp, how would i connect them up?

[Scoobydoo]

Using an RCA, into the input on the amp. You would use both terminals, but colour (usually red/white) doesn't matter.

[boon]

A splitter. But the amp will probably run absolutely fine with only 1 input connected.

[spark_38]

Isn't the left channel usually the mono input?

[boon]

Usually amps with 2 sets of inputs for mono output use a very simple 'summing' circuit (aka run the 2 channels together). The only time this can be a problem is if the 2 channels bass signal is out of phase (as they can cancel each other out) although this is extremely rare.

[Scoobydoo]

 spark_38 said:

Isn't the left channel usually the mono input?

If you are talking a stereo signal, then maybe, but that's not the case here. He is using a Mono (1 channel) amp with a mono signal (sub pre-out) so it makes no difference.

[sushi2hot4u]

 Scoobydoo']

[quote name='spark_38 said:

Isn't the left channel usually the mono input?

/quote]

If you are talking a stereo signal, then maybe, but that's not the case here. He is using a Mono (1 channel) amp with a mono signal (sub pre-out) so it makes no difference.

Well its a monoblock (1ch) amp so essentially if I understand it correctly, just connect mono L(or R) RCA from the amp to mono sub pre-out at the back of the headunit?

[Scoobydoo]

Pretty much, yep

[sushi2hot4u]

 Scoobydoo said:

Pretty much, yep

thank you scooby doo

[dean.ryan]

Monoblock amps combine both channels anyway, I assume the head unit just does it before the amp?

[Swindog]

Do you want rear speakers running off the amp? If not use the rear pre outs and on that channel flick the amp to l p f. You won't have any issues. I normally run big 6" components in front and sub rear and tune it all off the amp.