Questions on Small Vs. Large Settings for Denon 3802

Discussion in 'Archived Threads 2001-2004' started by Brian Ooten, Mar 29, 2002.

  1. Brian Ooten

    Brian Ooten Extra

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    I'm running Axiom M80TI's and an Axiom VP150 center. I run an SVS 20-39 sub powered by a Samson 700. I currently have my fronts set to small, and the LFE output on the receiver set to 80mhz. I'm wondering, if by setting my fronts to small am I missing a range of sound somwhere between the 80mhz and whatever crossover range my fronts at crossed at, like all sound between 80mhz and 120mhx
     
  2. Marc Rochkind

    Marc Rochkind Second Unit

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    Well, nobody answered yet, so I will try.

    You mention the fronts being "crossed." I'm not sure what you mean by that. They probably have an internal crossover for their various drivers, but this is unrelated to the bass-management crossover going on between the receiver and the sub.

    Anyway, I would for starters set the speakers to small, regardless of what their actual range is, and let the sub handle the low frequencies. The receiver will be crossing at some point, maybe settable or maybe not, but as long as it is not so high that the sub can't handle it, there will be no gap.

    If it is too high for the sub and there is a gap (the Avia test disc has lots of tones to check this), and you can't set it in the receiver, then I think you have to run the fronts through the sub, and let the sub do the crossover. The problem with this is that it doesn't address the other speakers.

    So, maybe the answer is a separate bass-management box.
     
  3. Brian Ooten

    Brian Ooten Extra

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    The fronts are of course crossed internally, but the receiver is also (unless I'm wrong here) sending signals down to a specfic mhz point out to the fronts to be played. My question is based on this point being higher than the point my LFE signal begins, thus creating an unplayed gap in my output. I'm probably making this sound very confusing because I bascially don't know what the heck I'm talking about, just trying to learn.

    Thanks for your reply, its appreciated!
     
  4. Greg_R

    Greg_R Screenwriter

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    Brian,
    You should only be using one crossover at a time. By setting your receiver's speaker settings to "small" you redirect anything under 80Hz to your subwoofer's input. Your subwoofer's crossover should be set as high as possible (or bypassed) in this configuration (i.e. it will pass the entire signal it sees at the subwoofer input). The explanation why is a little more complex (I'll try to make sense)...
    Every crossover has a "slope" that controls how quickly a signal is rolled off. These slopes are usually measured in dB/Octave. dB (decibel) is a logarithmic scale (i.e. the difference between 100dB and 110dB is a 10x increase in sound pressure level). A good primer about the physics of sound is here. If your crossover is set to 80Hz and has a slope of 24dB/octave, that means that at 40Hz your mains will be playing 24dB softer and at 160Hz your sub will be playing 24dB softer (assuming each speaker has a flat response over this range). BTW, each octave equals corresponds to a doubling in frequency. Anyway, because the crossover rolls off both your sub & mains at an equal rate, you'll get (hopefully) a flat response. If you are using your sub's crossover at the same time, these rates will differ and your flat response will turn into a dip (not a good thing). The crossover between the drivers in your main speakers is for a different frequency and is thus not affected by your LFE crossover setting.
    One other thing... humans can't hear "mhz". The range of human hearing (note I didn't say perception) is about 20 Hertz to 20,000 Hertz (20KHz or kilohertz). MHz = Megahertz & mhz = millihertz.
     
  5. Ten_Smith

    Ten_Smith Stunt Coordinator

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    I'm pretty new, so what I say may not be right, but I'll take a stab.

    First of all the Denon 3802 undoubtedly has an adjustable crossover. I have an 1802 and it does.

    Second. I think what Brian is missing is that the cross-over and the LFE are two different things. I don't believe the receivers cross-voer applies to LFE, only to the other channels. When you set the cross-over to a certain point, frequencies below this point are taken from non-LFE channels set to 'Small' and sent to the sub.

    If you set the cross-over to 80hz, that is a frequencie that it is very hard to locate so people will not know it is coming from the sub-woofer. By relieving your receiver and speakers from the duty of reporducing signals of
     
  6. Ten_Smith

    Ten_Smith Stunt Coordinator

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    Here's a more direct attempt at answering Brian's question, if I'm wrong I'm sure I'll be corrected shortly.

    There is no unplayed gap. The receiver cross-over can only effect the five non-LFE channels, and only does effect those set to 'Small.' For each of the 5 non-LFE channels set to small the cross-over passes the part of the signal below the designated point (e.g., 80hz) to the sub-woofer. So none of the signal is lost here.

    The LFE channel is un-affected by the cross-over, and just sent directly to the sub-woofer.
     
  7. Brian Ooten

    Brian Ooten Extra

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    Hey thanks for the information. Again, I'm not up to speed on all the issues of HT, but I'm learning. Your input is just incredible, the wealth of knowledge you guys have amaze me. Again thanks for taking the time to answer my questions.

    Thanks!!

    Brian
     

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