Improving bass

Discussion in 'Home Theater Projects' started by Allan Tan, Aug 22, 2003.

  1. Allan Tan

    Allan Tan Auditioning

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    What techniques can I apply to my room to improve the bass aside from speaker placement?

    I am just starting to build my HT, so I wanted to know the acoustical strategies I can use to make my room more musical. Something like raising the floor 3-4" above, or placing fiberboards...

    Any tips? Any references I can look at? Thanks!
     
  2. Wayne A. Pflughaupt

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    Allan,

    Whatever your room does to the bass you’re pretty much stuck with. About the only way to change the way your room makes bass sound is to do major modifications – open or close off to adjacent rooms, construct 45 degree corners, raise or lower the ceiling, etc.

    Aside from that, some people use bass traps to improve the way bass sounds. However, you can do much the same thing – cheaper and more accurately – with a parametric equalizer for your sub. Do a search on “Behringer Feedback Destroyer,” “BFD,” “parametric equalizer,” or “sub equalizer” and you’ll find enough material to keep you busy for days.

    As far as the musicality of the room, all I can do is speak in generalities not knowing anything about your room.

    Typically one of the worse things for musicality is a “live room” – one with hard floors, walls and ceiling. Hard surfaces reflect sound, and too many reflections makes everything sound indistinct.

    Therefore you want some surfaces to absorb sound, and some to disperse sound. A carpeted floor is one of the best ways to absorb sound and cut down on reflections. Sheetrock walls will absorb more sound that say, cinderblock walls. I’ve had good results in rooms with sheetrock walls with no other absorption than carpet.

    Another strategy is dispersion of the sound. This is accomplished with irregular surfaces. Things like book cases and other objects that might be place on a decorative tables (like vases and silk flower arrangements, for example) are effective for dispersion.

    Since the sound is typically aimed at the back wall, and will want to reflect from there right back toward the front, the back wall is an excellent place to apply dispersion techniques.

    Hope this gives you a place to start.

    Regards,
    Wayne A. Pflughaupt
     
  3. Neil Joseph

    Neil Joseph Lead Actor

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    If you currently have a concrete floor (?) then adding a sub floor would do wonders to the bass in the room, yes.
     
  4. Allan Tan

    Allan Tan Auditioning

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    Many thanks. [​IMG] I have a wooden floor and is just starting to build my room, so renovation is not a problem. Actually, I don't have a sub yet [​IMG] I just wanted to make sure that my room makes the most out of the sub that I will be using. BTW, what is a sub floor?
     
  5. Terry Montlick

    Terry Montlick Stunt Coordinator

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    Hi Allan,

    I would just add that it is ideal to use acoustical corrections first, and equalization on top of this for the "fine tuning". So if a room has a very strong bass resonance, I recommend tuned bass traps first, if possible - then a parametric equalizer like the BFD to put the finishing touches on your low frequency response.

    One advantage to a bass trap is that it can very nicely and safely even out a dip. A strong room resonance can be heard as a peak or a dip, depending on where you are in the room! It's a big standing wave, and how you hear it depends on what part of the wave you are positioned in. Significantly boosting a dip with an equalizer is not recommended, as it can be dangerous to both speaker and amplifier.

    Unfortunately, you won't know about bass problems until you've built your room! What I described is an ideal scenario, where your budget will allow you to install bass traps after major construction is completed. In any case, a parametric equalizer for your sub is highly recommended, like Wayne said.

    Regards,
    Terry
     
  6. Keith M.

    Keith M. Second Unit

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    The BFD seems like overkill for home theater use...

    How about one of the following:

    Rane PE-17 Equalizer
    Art 351 Equalizer


    Im considering adding one of these to my system, but am concerned with proper setup. Are there any websites/threads discussing the proper setup of the parametric equalizers inline with a subwoofer?

    I understand the actual settings depend on each individuals room/tastes...but I mean how do you set it up in a more scientific manner. Do I also need an analyzer tool?

    thanks in advance...
     
  7. Terry Montlick

    Terry Montlick Stunt Coordinator

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    Hi Keith,

    The Rane PE-17 is an excellent 5-filter parametric equalizer. The Art 351 is a 1/3 octave equalizer, so it will mate well with a 1/3 octave Real-Time Analyzer. They are both nice, simple analog processors. The parametric type will give you finer control.

    I recommend a Real-Time Analyzer and decent quality microphone to equalize your subwoofer. There are some inexpensive PC-based 1/3 ocave RTAs available on the Web. See:

    http://www.ymec.com/products/rale/
    2,800 Yen ($24!)

    http:/http://www.trueaudio.com/rta_abt1.htm
    $39.95 for 3rd octave version, more for higher resolution.

    You can also use the Analyzer software tool available free as part of WaveTools:
    http://www.sonicspot.com/wavetools/wavetools.html

    The latter does a straight frequency analysis (FFT) with a max resolution of 11 Hz, which works great for subwoofers - though you must feed it white noise instead of pink for a flat response. White noise should be low-pass filtered so as not to risk blowing up your tweeters! Anyone who wants to use this, email me and I'll send you a WAV file.

    As for how to equalize, it's just trial and error. Remember to always cut rather than boost wherever possible. The smallest amount of equalization to get a flat response (within a dB or so) is the best.

    Regards,
    Terry
     
  8. Wayne A. Pflughaupt

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  9. Keith M.

    Keith M. Second Unit

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    thanks Wayne!

    I read the setup guide, very informative!! I think im hooked... I will be placing my order this week.

    Are you using the BFD? What kind of results did you experience?
     
  10. Wayne A. Pflughaupt

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    Don’t have it myself – I already had other equalizers in place long before the folks here “discovered” the BFD.

    Equalizing the sub, when done right, will smooth out peaks and valleys in response and help set up a proper house curve. The results is smooth response from the highest bass notes to the lowest – all the same volume, no hot spots or dead spots. I like the way Forum member Richard Greene puts it: “An equalized $500 sub will sound better than an unequalized $1500 sub.”

    Regards,
    Wayne A. Pflughaupt
     

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