BFD sub eq help

Discussion in 'Archived Threads 2001-2004' started by Marc_E, Feb 23, 2002.

  1. Marc_E

    Marc_E Supporting Actor

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    Hi!
    I just setup a sonosub with soundstream monoblock amp (230watts @ 4ohms) and took my room measurements.
    Here they are
    http://photos.yahoo.com/bc/hayleys_d...c=ph%26.view=t
    and the numbers
    1678
    1887
    2091
    2293
    2595
    2895
    31.5100
    3698
    4092
    4584
    5089
    5688
    6386
    7188
    8091
    What do you think?
    Thanks for your help in advance.
    Marc_E
     
  2. Kevin C Brown

    Kevin C Brown Producer

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    Marc- Have you applied the "correction" to the Radio Shack meter numbers?

    Overall, not bad. You might just want to tame that peak at 31.5 Hz.

    Might also want to get finer measurements too someday. (The Stryke CD or the Autosounds 2000 CD.)
     
  3. Marc_E

    Marc_E Supporting Actor

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    Thanks for the reply,

    Yes I did apply the corrections:

    FREQRAW SPLSPL (comp)

    167889.5

    188795.0

    209198.5

    229399.5

    2595100.0

    289599.0

    31.5100103.0

    3698100.5

    409294.5

    458486.0

    508990.5

    568889.5

    638687.5

    718889.5

    809192.5

    Sorry, I should have included that in the first post.

    Marc
     
  4. Wayne A. Pflughaupt

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    Wayne
    Marc,

    In my opinion the 1/6-octave readings you supplied are fine for determining satisfactory EQ settings. And actually, we don’t need to know the uncorrected readings, just whether or not they are corrected.

    I’ve come up with these EQ settings based on your corrected readings:

    Set a filter for 1-octave bandwidth, centered on 36Hz and cut 6dB. This will reduce the peak at 31Hz and flatten response to ±3dB from 22Hz to 36Hz. (Centering the filter at 36Hz will give smoother response than setting it at 31Hz.)

    The next problem is the hole centered at 45Hz. It appears too wide to be a null, so I think we can deal with it.

    Set a filter for 1/3-octave centered at 45Hz and boost 8dB. If we are not dealing with a null, this filter will fill the in hole nicely. However, if the 8dB boost gives only few dB improvement, then we indeed have a null; in that case, forget the second filter. (The reason we are boosting so much is that the hole was deepened by the first filter.)

    These adjustments will give a marked improvement in measured response and should sound better, too. If you want to fine-tune further, I’d address the spike at 80Hz. Unfortunately you did not include readings above 80Hz, so I can’t tell where it peaks or how wide it is, which means I can’t recommend a fix.

    Good luck, and let us know how it turns out. If you’re not happy with the results of these recommendations, we can pursue it further.

    Regards,

    Wayne A. Pflughaupt
     
  5. Marc_E

    Marc_E Supporting Actor

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    Thanks fo rthe awesome reply Wayne.

    I did not include 80hz and above because I measured it with the mains still on and my crossover is at 80hz.

    Here they are

    809192.5

    899192.5

    1008688.0

    1118788.0

    1258080.5

    142.58484.5

    1608887.5

    Should measure it with the mains off? Be happy to. I'll post it tomorrow.

    Thansk again!!!

    Marc_E
     
  6. Kevin C Brown

    Kevin C Brown Producer

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    Marc- I always measure the following:
    1) sub alone
    2) mains alone
    3) sub plus mains
    The level of 3 must be greater than either 1 or 2. That makes sure that the phase is correct too.
    Even with an 80 Hz crossover, there is the crossover slope, so that you will still be getting appreciable output from your mains even at 40 Hz.
    And, I still don't know if I agree that every 1/6 octave is often enough. I have both the Stryke disc (every 1/6) and the Autosounds 2000 disc (every Hz from 10 to 98 Hz), and I can see (and correct) some small peaks with Autosounds that aren't apparent with Stryke. But Stryke is better than trying to do it by ear! [​IMG]
     
  7. Marc_E

    Marc_E Supporting Actor

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    Ok,
    well I re-measure with the mains off and things look different:
    http://photos.yahoo.com/bc/hayleys_d...c=ph%26.view=t
    FREQRAW SPLSPL (comp)
    167788.5
    188694.0
    209198.5
    229399.5
    2595100.0
    289599.0
    31.5101104.0
    36102104.5
    409799.5
    459193.0
    509192.5
    568788.5
    638889.5
    717677.5
    807778.5
    898283.5
    1008486.0
    1117172.0
    1257070.5
    142.56666.5
    1605857.5
    Wayne? Kevin? What do you think?
    Thanks again!
    Marc
     
  8. Kevin C Brown

    Kevin C Brown Producer

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    You've still got that peak from 31.5 to 36 Hz, and then a smaller one near 100 Hz.
    So after you set the filters in the BFD to attenuate them somewhat, you'd then remeasure.
    I don't have the BFD manual with me at the moment (with the freq table), but maybe Wayne could talk about the width and amount of attenuation you'd want for each of those peaks. [​IMG]
     
  9. Nick P

    Nick P Second Unit

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    Kevin,

    That's not always true but it is a general rule of thumb. With my mains on in phase I get huge cancellation effects. I have to run my subs out of phase from my full range fronts.
     

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