Subwoofer levels ... again

Discussion in 'AV Receivers' started by EricSm, May 14, 2003.

  1. EricSm

    EricSm Stunt Coordinator

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    A preface is important: I hate sloppy bass. I hate dominant bass. I love balance.

    I currently have my sub(Polk PSW350-- yes, it's not that good) about 4db hot using internal test tones on my Denon AVR-1803. For movies, even at this level it seems too low. The impact just isn't there and it's driving my batty. Everytime I nudge that knob higher I feel like I'm breaking some cardinal rule of proper home theater setup. What's wierd is that 2 channel audio in "stereo" mode is even worse than home theater. My bookshelf speakers genuinely produce more bass output set to large, sub to off when listening to 2 channel music. By more I don't mean aggressive amounts of sloppy bass. I mean it sounds natural and balanced. When I set the speakers to small(80hz crossover point), sub to on, and use stereo mode the bass output is simply bad. I don't understand what is going on. I would think that with my sub calibrated 4 db hot compared to the other speakers the bass would be too much... it's just the opposite. I've used the Avia and Sound and Vision disk to calibrate the subwoofer level and on those tests my subwoofer level is more like +6-8 db hot. I assume this is because of signal contribution from the front left speaker when measuring those levels.

    The simple answer seems to be just turn the subwoofer level up until it sounds good to you. But, I would like to understand what is going on. Why does it sound so bad on stereo mode? (Switching to direct mode the bass is too much-- which I think is full range signals sent to fronts and sub). Why do movies lack the impact you would expect?

    I've gone through all my receiver settings to make sure that I don't have any "artificial" bass limiters or movie modes on and everything checks out great.

    Thanks for any and all help!
     
  2. Jonathan M

    Jonathan M Second Unit

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    It could be due to a number of things:

    1. The placement of the speakers.

    2. The bass alignment of the bookshelves - I assume they are ported? If so, then they'll need careful blending in with the sub.

    You need to generate a test tone CD with tones from say 20-30Hz or so up to 120Hz or so, and play them whilst examining the SPL produced. You'll notice when you do this that you'll likely be getting some cancellation (nulls) at a number of different frequencies - this could cause the apparent lack of bass you are hearing. You can try and remedy things by altering the xover point on the sub (If it has one) and the phase on the sub (again - if it has one) whilst redoing the tests. This should give you some idea. You could also try moving the sub around to see if you can find a better location. One way to find one is to place the sub at your listening position, then walk around the room (or crawl to be at sub level!) until you find the loudest position - this is the ideal place for the sub. Unfortunately asthetics will likely cause compromises to be made.

    My advice is to first find the optimum position for the sub, then tailor it's xover point and phase to get the best (flattest) response you can. Make sure you recalibrate the sub after altering anything.

    Hope this helps.
     
  3. Lewis Besze

    Lewis Besze Producer

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    Besides the placement,the other obvious issue is,what can this sub do at real bass frequencies [below 35hz].If you missing "impact" that's where mostly the problem lies.Most commercial subs are most potent between 40-60hz.
     
  4. Pat Moynahan

    Pat Moynahan Auditioning

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    Make sure in the setup menu on the AVR1803 that the option subwoofer+main is selected. If you select this, the bass output will be at a normal level. Also, check your LFE levels on the receiver. I can't remember exactly how to do it, but I remember reading it in the manual. Hope this helps.[​IMG]
     
  5. Jeremy Anderson

    Jeremy Anderson Screenwriter

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    The -3dB point of the PSW-350 is an overly high 38Hz. It can reproduce down to 25Hz, but at an incredibly attenuated level. I used to have that particular model, and honestly there's just not a hell of a lot you can do to make it sound full with music. I tried everything. Also, the porting is at a very weird frequency. When I finally got mine placed to smooth out the frequency problems, the absence of boominess suddenly revealed some lovely port noise.

    Then I sold it and got a SVS 20-39CS+ rig. You've been given some good suggestions for things to try... but here's mine: As comedian Killer Beaz would say, "SAVE UP!"
     

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