Setting Question on the Denon avr 3801?!

Discussion in 'Archived Threads 2001-2004' started by Willy burz, Aug 6, 2002.

  1. Willy burz

    Willy burz Stunt Coordinator

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    Do you guys set the cinema eq to on or off? Also I have Mains that go down to 40 hertz, alot of people say if your mains can go down to 40 set them to large and +LFE. Others say just set them to small and let the sub do it!?!?

    Well aren't I wasting some of the speakers potential by cutting out at 80 hertz? Also the speakers will be fine as long as they are receiving clean power, even though they can't produce below 40... correct?!

    What's everybody's thoughts?
     
  2. Selden Ball

    Selden Ball Second Unit

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    You really aren't wasting anything by setting your mains to "small". Subwoofers do a much better job of reproducing low frequencies than all but the best floorstanding speakers. Rather, you are reducing the load on your receiver so it can do a better job of powering the higher frequencies. You are using the amplifier in the subwoofer to generate the low frequencies, which it is designed for.

    Another thing to consider is that if you set your main speakers as large, then you will have to make careful adjustments to the subwoofer's internal crossover network so the rolloff in its high frequency response matches the rolloff in the low frequency response of your main speakers.

    Simplisticly, whatever crossover frequency you use, your main speakers need to be able to produce sound to at least an octave lower than that (down to half the frequency). This is because the crossover filters are not a "brick wall".

    For example, the bass management in THX certified processors has a crossover frequency of 80Hz. Their crossover filters reduce the low frequencies going to the main speakers by 6dB per octave below 80Hz. They expect the speakers' own output to fall off at about 6dB/octave, too. The resulting falloff for the low frequencies being emitted by your main speakers thus is 12dB/octave. The matching falloff in the filtration of the subwoofer's response above 80Hz is 12dB/octave, since most subwoofers are linear well above that frequency.

    I hope these considerations help clarify things a little.
     
  3. Willy burz

    Willy burz Stunt Coordinator

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    But aren't you taking care of the frequency rolloff by having +LFE on the mains on, that way when the mains bottom out they are filled out by the sub which can go lower?
     
  4. Selden Ball

    Selden Ball Second Unit

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    Willy,

    LFE is a separate low-frequency-effects audio channel that may or may not be included on a particular disc. It's separate from the audio channels intended for your front main speakers. It isn't the same as bass management, so I'm not quite sure what you're asking.

    If your receiver is configured with "subwoofer on", the LFE channel (which includes frequencies in the range of 20-120Hz) is sent only to the subwoofer output.

    If you have a subwoofer and if any of your speakers are set to "small", then the frequencies below the receiver's crossover frequency are redirected from the "small" speaker channels to the receiver's subwoofer output.

    Some receivers include a separate "low frequency plus" setting (I'm not sure of the exact name). That setting lets you set the fronts to "large" and also will duplicate the front channel low frequencies in the subwoofer output. This enhances the low frequency experience in the frequency range where the main speakers and the subwoofer overlap. (Purists cringe at this idea, but many people enjoy the extra "punch" that this provides.)

    If you have no subwoofer, the receiver's front speaker channels have to be set to "large" and both the LFE channel and the low frequencies from your "small" speakers are sent to the front speaker outputs.

    Finally, some subwoofers are designed so that they can be connected to the front main speaker outputs and will do the low-frequency crossover themselves. They usually include a continuously variable crossover frequency adjustment, so you can set it to be "perfect" for the speakers you have. Setting this up right usually requires test tones, an audio level meter and lots of patience.

    The details of how a crossover manages the rolloff of the frequencies above and below the crossover frequency doesn't really change the description of where the low frequencies get redirected. Rather, those details determine just how smoothly the sounds from the various speakers are integrated at your listening position. Some receivers, for example, have several crossover frequency settings, so you can set the crossover frequency to something more nearly appropriate for the speakers you have. Most have a single fixed crossover setting, however, usually 100Hz.

    Does this clarify things at all?
     
  5. Willy burz

    Willy burz Stunt Coordinator

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    "Some receivers include a separate "low frequency plus" setting (I'm not sure of the exact name). That setting lets you set the fronts to "large" and also will duplicate the front channel low frequencies in the subwoofer output. This enhances the low frequency experience in the frequency range where the main speakers and the subwoofer overlap. (Purists cringe at this idea, but many people enjoy the extra "punch" that this provides.) "


    This is what I was talking about... There is a sub setting where you can keep the mains large but still run the mains bass throught the sub at the same time.
     

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