Should I Use One or Two Subwoofer Cables?

Robert Powers · 10-02-2003, 08:12 AM

I have the Polk RM7200 speaker package with PSW550 sub. I havn't hooked anything up yet but I plan to hook up the sub by using s sub cable from the receiver left and right preouts to the left and right line in of the sub.

Should I use 2 different sub cables (one for left and one for right) or would one cable be sufficient?

Circuit City has the same setup and they are only using one cable which is connected to the right line in of the sub.

Thanks!
Robert

ColinM · 10-02-2003, 10:18 AM

Pre-out as in you have no single (mono) sub out?

Robert Powers · 10-02-2003, 10:36 AM

ColinM,
I have a sub out on my receiver but according to the directions for the speakers it suggests to connect the sub cable from the left and right preouts of my reciever.

Thanks,
Robert

ColinM · 10-02-2003, 10:58 AM

And I wonder if your receiver has pre-amp inputs that mate with the outs - a main-out to main-in setup, so the the line level signals can then return to the amp, filtered by the sub.

Otherwise I don't see the advantage...

What receiver is this?

I only have experience with traditional sub-out a'la mono, but have seen and understand pre-out / main-in loops for outboard processing.

Hoping to help -

- CM

Robert Powers · 10-02-2003, 11:42 AM

The receiver is a Pioneer VSX-D908S.

Thanks!

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John Garcia · 10-02-2003, 11:51 AM

Use the sub pre-out with a Y adapter to both inputs on the sub. If you run it from the main pre-outs, you will have to set the mains to large and probably run the mains from the sub, not the receiver.

Don't use Circuit City as an example, as they don't know what they are doing half (or more) of the time.

Jeff Gatie · 10-02-2003, 11:56 AM

I concur with John. No use using the l/r preouts for the sub when you have a dedicated sub preout. Doing it through the l/r preouts removes your bass management and requires you to have the front speakers set to large, taxing your amp with reproducing lower bass that is just filtered out anyway. Also, never, ever take a setup at Circuit City as a guide, unless you use it for a guide of what not to do.

ColinM · 10-02-2003, 12:01 PM

Roger that.

Robert Powers · 10-02-2003, 12:29 PM

I agree with you guys but in the Polk Audio instruction manual it states the following in cap letters:

"DO NOT USE THE "SUBWOOFER OUTPUT" OR LFE JACK ON YOUR RECEIVER TO CONNECT THE SUBWOOFER". And then it states in smaller letters: "The RM7200 system features a powered sub that has a built-in, adjustable low pass filter to separate the low frequency signal (the bass) from the full range signal. The dedicated "sub output" jacks on most receivers also contain a fixed low pass filter. If your connect the sub to the receiver's "sub out" jack, the two filters will interact and reduce the fidelity of your system. If your pre-amp, processor, amp, or reciever has a spare set of front left and right pre-outs, connect them to the Line Level "In" jacks of the sub. Use well-shielded RCA cables. If your receiver has a single set of pre-outs and they are being used to deliver signal to an amp use Y cables."

Let me know what you guys think. This is my first powered sub so I don't know much about this.

Thanks!
Robert

ColinM · 10-02-2003, 12:53 PM

That's bunk information, I think. Nearly all subs (well, maybe 60 - 70%) are in action using the mono filtered sub out into the sub with a filter there, too, and it's no big deal at all. Just keep the sub's crossover knob fully open and the 2 filters will not be in each-other's way.

Heck - my AVR's cutoff is 100 Hz, and I often bring in the sub filter to 50 or 60hz, to see if I like it that way. Most of the time, I think I do.

I don't understand why Polk would say such a thing.