Sub and main speakers loose LFE range?!

Discussion in 'Archived Threads 2001-2004' started by Eliot.T, Nov 12, 2002.

  1. Eliot.T

    Eliot.T Auditioning

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    Edit::::Topic::::: Loose=lose...(it's late) ;/

    Hello,

    I wrote out a huge post, to only have it get deleted by my cable modem deciding to go offline when I hit "submit new thread"....sigh...so I'm going to try to make this shorter....

    My problem is that there seems to be a loss of bass in certain ranges between the main speakers and my sub. I have Polk RM6600 speakers with a Polk PSW350 sub. The way I have them connected is that the main speakers run into the sub, then to the receiver....I have the receiver(Yamaha 5560) sub option set to "main" so it sends "all signals 90Hz or below"(quoted from yamaha manual) to the main speakers, which get filtered out through the sub. So what is going on is the sub seems to be only producing VERY low bass frequencies, and the range of bass the sub makes seems to be limited to just VERY low frequencies.

    The Polk RM6600 speakers are not very big, so they can not handle much bass at all. So the bass that the speakers can't handle "should" be handled by the sub, but they are not. Let me give you an example using 1-100 for bass range with 1 being the lowest..... The main speakers(and every other speaker) produces bass levels lets say 80-100. The sub on the other hand produces bass levels between 1-50. So as you see, there is a range (51-79) that is not even being produced... "dead zone" if you will...

    I was wondering what I should do to close the gap on this dead zone of sound. My subwoofer has a low pass switch which has a range from 60-160 Hz. And I currently have it set to about 100Hz. The sub also has a phase switch, which i currently have set to 180.

    So basically the problem seems to be the sub is only producing very low frequencies of bass and is not producing mid-range levels which the main speakers can't handle, thus producing "dead zone" of sound.

    Any suggestions would be greatly appreciated...

    THANKS!!

    -ET
     
  2. Chris Tsutsui

    Chris Tsutsui Screenwriter

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    Well what you can do is raise the crossover frequency of the sub from 100hz, to 160hz. That should make the sub produce more upper bass frequencies that the mains can't produce.

    If you find that you can localize the bass from 1 sub too easily, then what I did was put the sub between the mains if that's possible.

    The only other option I see is to get new mains that can extend below 80hz.

    Adjust the phase so that the subwoofer doesn't cancel out bass with the mains. Try changing from 0 to 180 and listen for the volume level of the bass and if it's localized. I find that when a sub is out of phase with the mains, the bass sounds weird like it's only on one side of the listener's head.

    ----------------------------------------------

    On a side note: I have the opposite problem that you have that I've been searching for...

    My subwoofer plays too much high frequencies. When I play a white noise signal just through just the mains/surrounds channels, the subwoofer plays the white noise a little as well. As if the LFE channel is picking up information that the surrounds and mains are getting and playing it.

    I think this leads to audible voices that come from the subwoofer during movies.

    I tried adjusting the crossover to 40hz, but it still plays vocals at reference level watching Star Wars episode 2. I can hear Natalie Portman's voice through JUST my subwoofer connected via LFE to a 6.1 computer pre/pro.

    IS THIS NORMAL? Or do subwoofers play the "crossover" mid range frequencies that ALL the other channels play.

    Can anyone confirm that their sub plays vocals?
     
  3. Steve_Ma

    Steve_Ma Second Unit

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    ET, have you tried hooking up the sub via the sub out jack and letting reveiver do the crossing over? In your case, it cleary would seem to be worth a try to see of your still getting the gap in your bass response. If not, you know that the problem is how the sub is handeling the crossover. If you do try this, be sure to set the sub's crossover/filter on it's max setting to get it out of the way.

    If I heard a voice coming out of my sub, it would probably scare me into messing my pants. Maybe I need to learn more about vocal harmonics, but vocals at reference level, coming from a sub, with a 40hz cross doesn't seem right to me. I've never listened to JUST my sub, so I can't confirm this. I have heard some people report that talk radio and TV can sometimes do this as male speaking voices can be "bassy", but with a cross of 40hz?!?! Hopefully someone with more knowledge can shed some light there.

    What I do know, is that it's got to be expected that a sub is going to handle material well above the crossover point. Just as the mains need to be able to extend below the crossover point. Crossovers are not brick walls, but sloping layers. That's why good subs and speakers need to perform well above and below the crossover points for a better shot at good integration.

    Good Luck.
    --Steve
     
  4. Doug BW

    Doug BW Stunt Coordinator

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    Since you don't have your sub hooked up to the sub-out jack on the receiver, I believe you want to set the sub to "OFF" on the Yamaha, not "MAIN". I don't believe you're getting any of the LFE (the ".1" track) sent to the sub....only the bass that happens to be in the main channels.
     
  5. TonyTone

    TonyTone Supporting Actor

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  6. Keith Mickunas

    Keith Mickunas Cinematographer

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    Crossovers aren't a wall, they don't just cut sound at a specific frequency, they roll it off over a certain range. Crossovers vary in how they do this, and I don't know the specifics on how they work. But its essientially like this. If your crossover is at 100Hz, some sound above 100Hz will come to the sub, but more will go to the speaker, up to a certain point, say 120Hz, maybe higher, and some sound below 100Hz will go to the mains, but more will go to the subs. So the farther you get from the crossover point, the lower the sounds outside of it will be.

    If you're hearing Natalie's voice in your sub, is it very soft? It should be really low when compared to what's coming out of the mains.
     
  7. Chris Tsutsui

    Chris Tsutsui Screenwriter

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    I think I know what the problem is...

    I hear natalie's voice through my sub because my DAMN receiver's crossover point is fixed at 540hz!! I might as well add a midrange to my tempests with that kind of crossover point.

    It's the hercules GTXP sound card that must have been designed for multimedia equiptment.

    When I set my plate amp's crossover to 40hz, there becomes a gap in the frequency response and I get Elliot's problem.
    I guess my only solution is to hook up each of my mains through my PE plate amp/tempests and lose the LFE connection. I can set my receiver to 4 speaker mode and that should do the trick.

    I just upgraded my sound card from 6.1 to 7.1... hopefully the new driver will have crossover adjustment capabilities like Hercules said they would add. (the file is like 15megs and downloading)
     
  8. Eliot.T

    Eliot.T Auditioning

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    I hear Natalie's voice all the time, even when the movie is not on....in my dreams, at school....what does that mean?!?!
    [​IMG]
    -ET
     

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