Sub Equalizer

Discussion in 'Archived Threads 2001-2004' started by DanielSmi, Sep 23, 2002.

  1. DanielSmi

    DanielSmi Second Unit

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    Is there such a thing a an equalizer just for LF signals? I don't need an eq for 1k or 500k, etc. I need one for 50Hz, 80Hz, 40Hz, is there something on the market that focuses on bass signals only. This would be a great tool for taking out an peaks in your room, of which I have at least three?

    Daniel Smith
     
  2. EarleD

    EarleD Supporting Actor

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    There are are 2 for sale in the hardware section here, One is mine. Look for ART 351 EQ

    The BFD is another great product for this, much more flexible, but more complex to set up.

    Both work great if your willing to take the time to set them up properly

    Earle
     
  3. jeff peterson

    jeff peterson Supporting Actor

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    Do a search for Behringer or BFD (Behringer Feedback Destroyer) It lets you set the frequencies you wish to equalize. Many of us sub owners here use it
     
  4. AaronBatiuk

    AaronBatiuk Second Unit

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    Daniel,
    This isn't what you want to hear, but removing peaks (and more importantly, dips) in your room response is not a job best done by an EQ. The placement of the sub (and of the listeners) is the most important factor in your room's bass response.
    In many cases, you can smooth out the response just by moving your sub out of the corner of the room and/or away from the walls. Whenever the sub is next to a wall, it will excite all of the resonances created by that (and the opposite) wall. If the sub is in a corner, it literally excites every resonance in the room (for a rectangular room anyway), which is not something that you likely want to do.
    Here is, briefly, what you do: Using test tones (you will need at least 1/6 octave, preferably 1/12 octave), measure the response at the listening position(s). Plot this. The peaks represent room resonances that you need to elimintate. The dips represent room resonances that you need to try to excite more. The response from different seating locations will not be the same, so you may have to make some compromises. To help you to find out what your room resonances are, and how to place your sub/speakers to selectively turn them "on" and "off", go to harman international's website and download some tools and resources that they have available there:
    http://www.harman.com/wp/index.jsp?articleId=default
    Here you will find a paper called "Getting the Bass Right" and an excell spreadsheet called "Waves and Modes: A Room Resonance Calculator". Using these two tools, I was able to improve my own system dramatically, just by moving the speakers a foot or so. Without these tools, I never would have known where to move them to.
    With the right software, you can also use a computer to automatically generate the test tones and plot the response. You will need to use a calibrated microphone, such as using the output jack of a SPL meter.
    Even after smoothing out the peaks and dips, you may find that you have to equalise the response to flatten it out. The best thing to use is a parametric equaliser. This type allows for complete adjustment of all parameters including frequency, level, and "Q" (or relative bandwidth). Note that an EQ is only useful for lowering the levels; it cannot be used to boost levels to compensate for a dip in the response. A 10 dB dip (a smallish dip) would require 10 times the power in order to boost it up to par. A 20 dB dip would require 100 times the power. Not something that you amps or speakers will happily do for you!
    So, play with the sub placement first. It is usually one of the easiest things you can do, and can have the most dramatic effect on the room response.
     
  5. DanielSmi

    DanielSmi Second Unit

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    I've already measured my freq response of my room. I have a Velodyne HGS-10 heres what I got:

    Volume setting: -10
    C-weighting Crossover: 80Hz, Low Pass: 20Hz (48dB/octave)
    10Hz: 59.5dB
    12Hz: 70.5dB
    15Hz: 86.5dB
    18Hz: 92dB
    20Hz: 93dB
    23Hz: 94.5dB
    25Hz: 96dB
    28Hz: 99dB
    30Hz: 99dB
    33Hz: 102.5dB
    35Hz: 103dB
    38Hz: 106dB
    40Hz: 104.5dB
    43Hz: 99dB
    45Hz: 101dB
    48Hz: 107dB
    50Hz: 108dB
    53Hz: 102dB
    55Hz: 100dB
    58Hz: 99dB
    60Hz: 98.5dB
    63Hz: 97.5dB
    65Hz: 102dB
    68Hz: 102.5dB
    70Hz: 108dB
    73Hz: 100dB
    75Hz: 97.5dB
    78Hz: 105dB
    80Hz: 108dB
    83Hz: 103dB
    85Hz: 106dB
    88Hz: 98dB
    90Hz: 101.5dB

    I'd show you the graph but I don't have a scanner at home but I have peaks at 43Hz, 50Hz, 70Hz, and 80Hz.

    I should have my computer fixed by the end of the week so I'll have to try out those programs. I don't really have any dips just peaks. I'm in the same boat as you I really don't have any idea where to put my sub, so try out those programs.

    Daniel Smith
     
  6. Sonnie Parker

    Sonnie Parker Second Unit

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  7. Kevin C Brown

    Kevin C Brown Producer

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    Aaron is right, except that most people don't have a lot of flexibility in placement for a sub.

    Sub eq'ing can work really well, if you spend the time doing the measurements.

    There are also units out there from Rane and Symetrix. Just a parametric eq.

    But I believe that the BFD is the most flexible, and actually once you get the wierd interface down, actually quite easy to set up. Really reasonably priced too. ~$120 or so if you look around.
     
  8. David Judah

    David Judah Screenwriter

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    You've already done the hard part(the measurements), so setting up the equalizer will be a breeze.

    I, like many others here, use a BFD and it made a big difference in my room.

    DJ
     
  9. DanielSmi

    DanielSmi Second Unit

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    where could I get one at for $120? Does the company that makes it have a website?

    Daniel Smith
     
  10. Kevin C Brown

    Kevin C Brown Producer

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  11. Bill Polley

    Bill Polley Second Unit

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  12. Sonnie Parker

    Sonnie Parker Second Unit

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