Low freq. room gain calculator?

Discussion in 'Speakers & Subwoofers' started by Ray_C, Mar 13, 2004.

  1. Ray_C

    Ray_C Stunt Coordinator

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    Hello All,

    Aside from the obvious method of using reference tones and an SPL meter, are there any online resources that can somehow give you estimates of freq. peaks (especially for low end/sunbwoofers) depending on your room dimensions? Perhaps something than you can plug in numbers that correlate to your dimensions, in my case one with an alcove that can't be closed off. I have a disc with test tones that go all the way down to 20Hz, but they're in 10hz increments, so I'm wondering if I'll be missing things in between. I'm planning on getting a Behringer Feedback Destroyer, so it would be nice to have some figures to try out that I may not be able to test with the tones that I have.
     
  2. Julian Data

    Julian Data Second Unit

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    Hmm..

    You could take the speakers outside at either 1m or 2m distance and measure them with a good mic and analyzer and then bring the speakers back into the room and perform the same measurements.

    If you're using the old Rat Shack SPL meter be sure to get the corrected dB readings. It should be on this forum or elsewhere on the 'Net. The old analog meter was pretty erroroneous at low Hz.
     
  3. PaulT

    PaulT Supporting Actor

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    Ray,

    Go here and get a tone generator program and burn your own tones in 1/6th Octave increments:
    http://www.nch.com.au/tonegen/index.html

    Once you get your BFD you could zero in on the frequencies (peaks and dips) within 1Hz in order to set your filters more accurately.

    Room Response programs will never be close to being as accurate as measuring your own room. FYI, a couple of programs I have found:

    http://www.harman.com - search around for a program called 'Room Mode Calculator'

    Go here:
    http://www.pvconsultants.com/audio/frdgroup.htm

    for a great array of programs, including the PEQ program for the BFD written by a Forum Member (Anthony Gomez) and the RRC Room Response Calculator (Yavuz Aksan).

    Tony Gomez also has 1/12th Octave tones and links to his program here at:
    http://beyond_gomer.tripod.com/

    Of course you'll need to check out the BFD page at:
    http://www.snapbug.ws/bfd.htm

    and also make sure you have the RS Meter corrections stated above. SVS Subwoofers has them listed on their site and they can be found on the web via google.
     
  4. Ray_C

    Ray_C Stunt Coordinator

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    Thanks much Julian and Paul. Paul, I have a Mac, so I don't see a lot of that software being useable for me, but I get the idea and I appreciate the info. I'll look into it further and see If any of these programs can be used on my mac. Lot's of good info.
     
  5. PaulT

    PaulT Supporting Actor

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    If you can run an emulator (or equivalent Mac program) that does excel spreadsheets, then the PEQ and RRC programs should run for you. You can download the 1/12th octave files and burn them to CD and you should be set.

    Good luck
     
  6. Ray_C

    Ray_C Stunt Coordinator

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    Yes, I think that simply downloading and using the 1/12th tones is a good place to start. Thanks again.
     

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