Sub wiring, Ohms, and RMS... oh my

[Sunriver61]

So this could be a basic question, however what's the consensus in taking two 4 ohm subs, wiring in parallel to drop them to two (and a mono feed), and then having a mono channel amp run them at 2 ohms. There's a reason for this madness? I'm just not sure if it can or "should" be done. Reason I say this is that I've got a mono sub coming from the crossover, and while yes, I could split it and run a two channel amp I'm wondering if I could do it the way I described above. Usually I take things normally, but this install is a little wacky.

Thanks for positive encouraging educating help

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[Dafaseles]

Actually, wiring like you described is normal. Using a 2 channel amp for the subs is more abnormal... and how do you have "a mono sub coming from the crossover"? I don't think I'm quite following what you're saying

 

[Sunriver61]

Actually, wiring like you described is normal. Using a 2 channel amp for the subs is more abnormal... and how do you have "a mono sub coming from the crossover"? I don't think I'm quite following what you're saying

Sorry, it was late and I just didn't type correctly. the crossover does have a L/R out for the sub.

 

[YourNameHere 10+ year member]

the crossover does have a L/R out for the sub.

Huh? LOL

 

[hispls 5,000+ posts]

Sorry, it was late and I just didn't type correctly. the crossover does have a L/R out for the sub.

That is unusual as you really cannot detect stereo separation below 200hz or so.

Running subs parallel into a mono amp is the norm and different impedance subs exist primarily in order to have more options to properly mate to whichever amp you chose based on how many subs you intend to install.

 

[metalheadjoe 10+ year member]

That is unusual as you really cannot detect stereo separation below 200hz or so.

Running subs parallel into a mono amp is the norm and different impedance subs exist primarily in order to have more options to properly mate to whichever amp you chose based on how many subs you intend to install.

Why is it any more unusual than a receiver having stereo subwoofer outputs or sub amps having stereo inputs?

 

[Dafaseles]

Sorry, it was late and I just didn't type correctly. the crossover does have a L/R out for the sub.

Can you describe what the "crossover" is? I think you might be mistaken

 

[audiobaun 5,000+ posts]

https://www.the12volt.com/caraudio/subwoofer-wiring-diagrams.asp?Q=2&I=41
Wiring for 2= SVC 4 ohm subs for a final load of 2 ohm at the amplifier

 

[hispls 5,000+ posts]

Why is it any more unusual than a receiver having stereo subwoofer outputs or sub amps having stereo inputs?

Because in those low frequencies you can't detect direction of the sound and more often than not people running multiple woofers have them sharing the same airspace and port so you really want them all getting identical signal.

 

[metalheadjoe 10+ year member]

Because in those low frequencies you can't detect direction of the sound and more often than not people running multiple woofers have them sharing the same airspace and port so you really want them all getting identical signal.

You missed my question.

 

[Sunriver61]

Can you describe what the "crossover" is? I think you might be mistaken

ec20b.

 

[Dafaseles]

ec20b.

Ok,I get it. You have an active crossover system.
Even though, don't get caught up in left and right signal for the sub. Send those sub RCA's to a monoblock amplifier, wired to the correct impedance, and enjoy. That's honestly how 99% of subwoofer installs are done.
Just make sure to set your gains correctly. Wouldn't want to spend all that time and money in your system just to ruin the equipment

 

[hispls 5,000+ posts]

You missed my question.

Not sure how that wasn't an explanation of why stereo outputs or inputs on amps is uncommon.

 

[metalheadjoe 10+ year member]

Why is it any more unusual than a receiver having stereo subwoofer outputs or sub amps having stereo inputs?

Not sure how that wasn't an explanation of why stereo outputs or inputs on amps is uncommon.

You gave a fantastic explanation of the nondirectional property of lower frequencies, but that wasn't what i asked. Therefore, you missed my question, and my question stands.

 

[hispls 5,000+ posts]

You gave a fantastic explanation of the nondirectional property of lower frequencies, but that wasn't what i asked. Therefore, you missed my question, and my question stands.

Ok, let's come at this from another direction. If you can't hear stereo separation below 120hz why add complexity (and more cost) to your design if you're a manufacturer? If many people who are in the market for a sub amp will be running multiple subs sharing the same airspace wouldn't they be trying to buy a product that delivers identical signal to all of the drivers?

In short, the reason nobody is offering stereo options in subwoofer systems is because nobody wants it and nobody wants it because it adds nothing but extra cost and complexity.