To EQ. or not to EZ for subs.

Discussion in 'Archived Threads 2001-2004' started by Jerome Grate, Dec 10, 2001.

  1. Jerome Grate

    Jerome Grate Cinematographer

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    I've read some of the posts here answering questions about subs and the frequencies. I've noticed that some of you have eqs hooked up to your SVS subs or what eve subs you have. Here's what I have, I have the two DIY subs hooked up to a Numark mixer with volume control and a six band eq. It sounds great but I need to update and replace the mixer.

    1. Do you have a 10 band or 12 band eq hooked up.

    2. what are your settings, the frequencies.

    3. How does it help, what does a 10 band or 12 band do to the sound.

    Thanks for your help.
     
  2. Bhagi Katbamna

    Bhagi Katbamna Supporting Actor

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    The first thing you should do is to bypass the eq, then get a Radio Shack SPL meter and a CD that contains low frequency test tones. Play the test CD and note down the dB on the Radio Shack meter and see which frequencies need to be corrected. Then see if you need an eq. I had an ART 351 31 band eq but even that did not have enough flexibility or power to tame a 35Hz to 40Hz room peak. I recently bought a Symetrix 551e which is a parametric eq(can more finely adjust the frequency at which boost or cut is applied), this finally gave me flat bass to below 20 Hz.

    Also keep in mind that there is a correction to the RS SPL meter at very low freq(20Hz to 50 Hz). Hope that helped.
     
  3. Jerome Grate

    Jerome Grate Cinematographer

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    Yep, that did, now if someone can give me the formula to do such a test.
     
  4. Bhagi Katbamna

    Bhagi Katbamna Supporting Actor

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    What do you mean by "formula"?
     
  5. Wayne A. Pflughaupt

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    Jerome,

    A 10-12 band equalizer is really just an upscale tone control. It is not made to correct the room-induced low frequency anomalies of a sub. Look at the sliders. There are only two bands below 100Hz.

    Do as Bhagi suggested. Get a SPL meter, a CD with low frequency test tones, 1/6 octave or finer, and a good parametric equalizer. After you take readings post them here and we can help you EQ your sub.

    Happy Holidays,

    Wayne A. Pflughaupt
     
  6. Chuck Kent

    Chuck Kent Supporting Actor

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    I have had a powered sub in my home theater for several years. But until I bought a parametric equalizer, I did not have a clue as to how good bass can be.

    I too had a 40 Hz bass mountain to tame. Shaving the 40 Hz hump down allowed me to turn up the rest of the bass. Now I have bass I can feel as much as hear.

    A parametric eq. is worth every penny!!!
     
  7. Jerome Grate

    Jerome Grate Cinematographer

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    I'm back, the formula I'm talking about is what do I look for when using the SPL meter, I have one and I was able to calibrate the five channels, but never used it for a sub. What do I look for and where do I get a CD that tests bass. Are we talking about tones and pings on this CD.
     
  8. derek

    derek Second Unit

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    I used a 31 band eq to setup my 4 subs (groups of two located in opposite corners of my rectangular room.) The difference was quite pronounced...tamed a bad 40-50hz peak and have audibly smoother response within 5-10db (40-100hz) and was able to juice up the low end response (20-40hz) a bit. I used the bass test cd founnd at www.stryke.com .
     
  9. Bhagi Katbamna

    Bhagi Katbamna Supporting Actor

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    Stereophile also has a test CD but the stryke one is probably better. Set your SPL meter the same way as you did for calibrating the channels. Then play the CD, record the dB level at all of the low frequencies and see what adjustment is needed.
     
  10. BruceD

    BruceD Screenwriter

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    The stereophile test CD (#2 and #3) I have both, doesn't work well for testing room modes, because they use warble tones which don't let specific frequencies build up into room modes.

    This type of warble test tone is good for testing the main-to-sub crossover though.

    BruceD
     
  11. jeff peterson

    jeff peterson Supporting Actor

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    For those of you using the Stryke disc; are you using the sine waves? If so, for how long? I've read here (espcially from Tom V aka SVS Tom)about the dangers of running a sine wave through your subwoofer too long and frying the voice coil.
     
  12. Kevin C Brown

    Kevin C Brown Producer

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    Wayne published some suggestion here on HTF (somewhere) about sine waves. I thought it was useful (as well as funny):
    1) Do not use test tones at 115 dB.
    2) Do not use test tones for 30 min.
    I have done numerous passes with the Autosounds 2000 CD, usually in between 75 - 95 dB, for 10-15s per each Hz (10 - 98), and I haven't had any problems with my sub melting down. [​IMG]
     

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