Should I Use One or Two Subwoofer Cables?

Discussion in 'Speakers' started by Robert Powers, Oct 2, 2003.

  1. Robert Powers

    Robert Powers Stunt Coordinator

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    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
     
  2. ColinM

    ColinM Cinematographer

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    Pre-out as in you have no single (mono) sub out?
     
  3. Robert Powers

    Robert Powers Stunt Coordinator

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    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
     
  4. ColinM

    ColinM Cinematographer

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    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
     
  5. Robert Powers

    Robert Powers Stunt Coordinator

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    The receiver is a Pioneer VSX-D908S.

    Thanks!
     
  6. John Garcia

    John Garcia Executive Producer

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    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.
     
  7. Jeff Gatie

    Jeff Gatie Lead Actor

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    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.
     
  8. ColinM

    ColinM Cinematographer

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    Roger that.
     
  9. Robert Powers

    Robert Powers Stunt Coordinator

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    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
     
  10. ColinM

    ColinM Cinematographer

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    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.
     
  11. Jeff Gatie

    Jeff Gatie Lead Actor

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    Turn the low pass filter on the sub up to it's highest setting. Then attach the sub using the sub out on the receiver. I doubt the highest setting on the sub is lower than the crossover in the receiver, but you can check to be sure. This Polk Manual issue has been discussed in detail here before, you might want to do a search for it.
     
  12. ColinM

    ColinM Cinematographer

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    http://www.polkaudio.com/home/faqad/...cle=bassmanage

    In reading this, there are a lot of "May" and "Might" phrases in there - and some huge assumptions and theories.

    "When using the sub out jack with palm-of-hand sized satellite speakers, you are forced to use the Small setting on the front left and right speakers (more about this later). The Small setting introduces a high pass filter on the satellites in addition to the one that is built into the satellite's crossover. Bottom line, this arrangement severely degrades the sound of the satellite speakers and exacerbates the hole-in-the midrange effect. "

    What?

    If that were true, I think WE would know about it.

    If the Hi pass filter is applied in the digital realm, the signal then amplified, it's not the same as being forced through 2 passive crossovers, like the above paragraph states - it's just a bass-less audio track. Much like keeping the crossover knob fully open, only it's true in that the sub will pass the signal through a filter internally. But I can't see that being a real world problem.
     
  13. John Garcia

    John Garcia Executive Producer

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    The only real reason I can see for them to recommend this setup is because the sub's high pass is tailored to the frequency response of the satellites (a-la BOSE), and you may or may not have the ability with your receiver to accommodate a similar high pass. With their smaller satellites, I would recommend using their method if your receiver cannot set a x-over higher than 100hz, but with the 7200, the satellites should be able to handle a 100Hz or lower x-over.
     
  14. Guest

    I was Just Wonderin Maby you would No and could Help me I have an Older Surround Sound Amp it has a Pre Out Sub Plug and A Pre Out Center Plug i have the sub hooked up then the Pre out Center Plug i have a Y splitter Plug on it then i have a RCA Cable pluged in to it witch then goes in to my Power Amp Witch Then Center Spaker Plugs in two The Power Amp my Qwestion is do you think the RCA Y Splitter im useing is ok or should i Use a Better one like a Monster Cable Y Splitter??
     
  15. MarvinJr

    MarvinJr Stunt Coordinator

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    How do yall keep digging up these old threads? This one is 6 years old! lol
     
  16. David Willow

    David Willow Babbling Idiot
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    Ken,

    I'm not sure I completely understand your question, but I will say that Monster is not necessarily better than the one you are using. In most cases, the only difference is the price. Monster is WAY too expensive.

    All you need is a single cable to the sub. What are you using the pre-out center for???
     
  17. Jeff Gatie

    Jeff Gatie Lead Actor

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  18. David Willow

    David Willow Babbling Idiot
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