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  1. #1
    Forum Regular anamorphic96's Avatar
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    Subwoofer Output Question

    I have recently acquired the NAD 720BEE and it has a sub out jack that has a fixed crossover point of 100hz at -3db. The mains run full range since this is just a stereo receiver. My question is. Since this sub out is not your typical full range pre out can I still adjust the crossover on my sub at say 60 to 80hz since the output on the receiver is 100hz and below. Or would it be best to use the pre-out jacks. I could use the pre out jacks but would need to get y adaptors. I would like to just use the sub out for simplicity sake.

    Thanks

  2. #2
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    if your sub has a stereo input,use them use the pre outs not your typical lfe input.only then can you lower your sub crossover without losing signal,because you will lose the signal between 80 and 100 if you use the sub out on the nad.

    bill

  3. #3
    Suspended markw's Avatar
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    dunno about that

    Quote Originally Posted by musicman1999
    if your sub has a stereo input,use them use the pre outs not your typical lfe input.only then can you lower your sub crossover without losing signal,because you will lose the signal between 80 and 100 if you use the sub out on the nad.

    bill
    This is not a LFE output like those on a HT receiver. It's just a summed mono signal. If the full range is still supplied to the mains, and I believe it is, and his mains can handle the difference, then he will lose nothing by adjusting his crossover lower than 100hz. He'll just prevent having the sub competing with the mains on the upper bass.

  4. #4
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    Yep I wouldn't worry about it. Just use the sub out, and adjust the xover on your sub anywhere under 100Hz

  5. #5
    Loving This kexodusc's Avatar
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    markw's right

    Quote Originally Posted by markw
    This is not a LFE output like those on a HT receiver. It's just a summed mono signal. If the full range is still supplied to the mains, and I believe it is, and his mains can handle the difference, then he will lose nothing by adjusting his crossover lower than 100hz. He'll just prevent having the sub competing with the mains on the upper bass.
    The speakers will run full range, the -3 dB point (likely a 2nd order slope is 100 Hz)...when using the crossover on the sub, you're adding a second slope. So just keep that in mind - probably not a big deal above 100 Hz (might actually be beneficial in cutting the bass frequencies that are directional). So if you set your subs xo to 80 Hz, it'll be -3 dB at 80 Hz, and then get another 12/octave reduction at 100 Hz....not really a 4th order but whatever.

    Go ahead and experiment. If the speakers are running full range, I'm guessing 40-60 Hz is probably where you want the sub to take over.

  6. #6
    Forum Regular audio amateur's Avatar
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    Just a quick question kex, when you say running full range, how full range IS the signal?how low does it cutoff? 40Hz? 20Hz? 3Hz?

  7. #7
    Loving This kexodusc's Avatar
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    Quote Originally Posted by audio amateur
    Just a quick question kex, when you say running full range, how full range IS the signal?how low does it cutoff? 40Hz? 20Hz? 3Hz?
    Depends on the upstrem sources, but these days, at least 20 Hz, and quite often lower - IMO, 20 Hz is more than sufficient - I can't hear any differences in notes or tones below mid 20's really, it's just low and deep. Below 18 Hz, it's pretty much felt, not really heard...

    Most pop/rock/metal music doesn't go below 30Hz, though alot of synthesized bass/drums will go lower, and classical (even Jazz) can go well into the low 20's.

  8. #8
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    I was refering more to the NAD amp (or any other amp for that matter, not so much music), as in how low does it cut off its full range signal to the fullrange speakers? You'd think it would filter under 20Hz, or else it might be overkill for the speakers. Well I guess you did answer my question , it depends on the upstream source. ok.

  9. #9
    Loving This kexodusc's Avatar
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    Quote Originally Posted by audio amateur
    I was refering more to the NAD amp (or any other amp for that matter, not so much music), as in how low does it cut off its full range signal to the fullrange speakers? You'd think it would filter under 20Hz, or else it might be overkill for the speakers. Well I guess you did answer my question , it depends on the upstream source. ok.
    By upstream sources, I meant everything in front of the speakers - receiver/amp/pre-amp/cd player, etc..the NAD included.
    Standard is to rate them 20Hz-20KHz these days, that DOESN'T mean they won't exceed those ranges...many do. I can't imagine anything built in the last 5 years that wouldn't have a range down to 20 Hz...possibly Bose....

  10. #10
    Forum Regular anamorphic96's Avatar
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    Thanks for the advice everyone. I will experiment and see what happens. If all else fails I will use the pre-outs.

  11. #11
    nightflier
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    Just one note: not all subs have adjustable frequency crossover when using the RCA inputs. For example, the DefTech ProSubs only allow that adjustment for the speaker level inputs. Check your sub's documentation to make sure.

    Alternately, using the speaker-level in/outputs on your sub may provide that extra control you'r looking for (albeit with a lot of extra speaker wire).

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