Mains w/subwoof: How to wire? (CSW T500)

Discussion in 'Speakers' started by Shamus, Jan 24, 2003.

  1. Shamus

    Shamus Auditioning

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    I have the CSW T500 mains, which are floorstanding with integrated 300w subs. It is possible to wire them with just a normal speaker wire, and the subwoofer input is bridged from the input of the unpowered portion of the mains. Or you can wire the subs with an RCA type subwoofer input and slave the other powered sub from the first.
    The advantage to the first, simpler setup, is I get stereo low freqs and less wiring.
    The question is: is there an audible difference in using the sub-out from the amp, and using separate sub wiring?
    Current amp setup is Mains-large, sub-no.
    Comments?
    Thanks in advance...
     
  2. Anthony Urzi

    Anthony Urzi Stunt Coordinator

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    i have a question on that...if you're not using the amps sub out in a dolby setup, are you just gettign left right low freqquences? It sounds liek yoru LFE channal would be abanondoned with that wireing setup...or are oyu talkign strickly a stereo setup?

    I'm considerign these speakers and have the same question,
     
  3. Anthony Urzi

    Anthony Urzi Stunt Coordinator

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  4. Mike Sloan

    Mike Sloan Second Unit

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    If we disconnect the bi-wire jumpers, drive the woofer section with sub out from a DD receiver, and set the front speakers to small you will get an overall response curve that does not sum flat. This is because the receiver's high pass crossover is in series with the loudspeakers crossover high pass crossover, resulting in a net crossover rolloff that is the sum of both. Same with the subwoofer low-pass. The result is that each crossover is too sharp, resulting in the dip at around 80 Hz. Always leave the jumpers in place. With jumpers in place, you can treat the speaker system as a single, full range speaker. It helps if you accept that the number of drivers behind the grilles is not material, only the fact that the total response smoothly spans the frequencies of interest. Then when the receiver is set as recommended, a band of 80Hz and up is sent to the speaker level inputs of the T500. The overall response of the T500 now reflects only the high pass curve of the receiver, since it is a "single full range driver" that goes down to 22 Hz. So in essence you have one of the world's biggest satellites with a low frequency cutoff that is whatever the receiver tells it to be. This could be 60 Hz, 80Hz, 100Hz or whatever, the T500 doesn't care. The receiver is doing the job of keeping the "undesired" bass out of the T500. The desired bass then comes from the receiver via the sub output. Assuming the receiver manufacturer has done their job correctly, the sub out should be a perfect compliment to the satellite output curve. This results in the overall response of the T500 returning to flat. In other words, the subwoofer signal being sent to the T500 should contain exactly what the receiver doesn't send from the speaker outputs. When these combine in the T500, the result is full range response. Therefore the T500 is not actually getting superfluous or conflicting signals, the processors action prevents this.
    If the main speakers are not set to small, then the T500 gets redundant signals below the processors crossover frequency. This sums to a reasonably undesirable non-flat curve with a dip at 80Hz followed by a bump at 30Hz-40Hz.
    In theory, setting the receiver to large front channels and using only the speaker level input to the T500's will result in ideal response. In actual practice, room acoustics play almost as much a role in perceived bass performance as the speakers themselves. Standing waves within the room can make theoretical perfect bass not so perfect in any given room. Therefore it is often nice to have the additional adjustment capability that use of the sub-output provides.
     

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