1. Visit this thread for your chance to win a selection of Lionsgate action films on UV!
    Dismiss Notice

My frequency response and a question

Discussion in 'Archived Threads 2001-2004' started by EarleD, May 26, 2002.

  1. EarleD

    EarleD Supporting Actor

    Joined:
    Aug 27, 2000
    Messages:
    728
    Likes Received:
    3
    Here are the results of my subs freq sweeps. I used test tones of 20,25,31.5,40,50,63,80,100,125.

    Heres the numbers without the RS comp added. These are post EQing.

    20hz---75db
    25hz---78db
    31.5---79db
    40hz---84db
    50hz---81db
    63hz---82db
    80hz---78db
    100----72db(better now)
    125----81db

    I figure with the RS compensation I have a great house curve.

    My main concern is the large dip at 100hz, is this likely to be audible?

    Would moving the front speakers help with this dip? I assume it is the front speakers interacting with the sub resulting in the cancellation at 100hz.

    Earle

    Check out my webpage for equipment list and pics of speaker placement.
     
  2. Wayne A. Pflughaupt

    Joined:
    Aug 5, 1999
    Messages:
    6,061
    Likes Received:
    25
    Location:
    Katy, TX
    Real Name:
    Wayne
    Hi Earle,

    Doesn’t look bad. However, if these are non-corrected numbers, you might have too much boost below 40Hz. I’ve found that a house curve sounds better (at least with music) if it levels off at about 32Hz.

    I would advise getting some 1/6-octave test tones, though. You might find that there are problems between the frequencies you’ve tested. Also, the 100Hz dip might turn out to be narrower than it looks now. I was using 1/3-octave tones until a few months ago, and I was amazed to find out how much vital information I was missing when I finally got 1/6-octave.

    Hard to say if moving the speakers will help the 100Hz problem. If the sub is close to the mains you might try adjusting the phase control on the sub (if it is continuously variable). Proper phase adjustment can alleviate some interaction problems between the subs and mains.

    If you'll post the value of the slopes of the high pass and low pass filters, I'll make a recommendation.

    Regards,
    Wayne A. Pflughaupt
     
  3. EarleD

    EarleD Supporting Actor

    Joined:
    Aug 27, 2000
    Messages:
    728
    Likes Received:
    3
    Wayne I was hoping that you would jump in here.

    I understand what you mean about too much house curve and dropped the lowend 5-6db.

    My Outlaw ICBM is doing the bass management for the entire HT. I have the ICBM between the preouts and amps.

    The fronts Xover is set to 60hz, center to 80hz, surrounds to 60hz and rear centers to 60hz.

    All speakers can easily play to the xover location.

    I changed to numbers to what they are now, after some minor adjustments.

    Thanks

    Earle

    The LP crossover slope os 12db/oct I have the option of going to a 36db/oct slope.
     
  4. Arnel Enero

    Arnel Enero Stunt Coordinator

    Joined:
    May 2, 2002
    Messages:
    106
    Likes Received:
    0
    Well, simply said, a dip is much better than a peak, especially at that region where even the slightest boominess is most notable to some people.

    There are two possibilities I can think of:

    1. Your front speakers have a dip in that region.

    -- or --

    2. Your subs are effectively firing out-of-phase with your front speakers. Note that I'm not talking about the Phase switch setting, but the ACTUAL, consequential phase relationship due to relative position. If this is the case, the crossover region's overlap will cause a cancellation centered around 80Hz-120Hz.
     
  5. EarleD

    EarleD Supporting Actor

    Joined:
    Aug 27, 2000
    Messages:
    728
    Likes Received:
    3
    I'll see if I can run some 1/6 oct tones later today and get back here the the results.

    Arnel,

    I set the phase by running a tone at the LP xover freq(60hz in my case) and stuck with the phase which had more output

    Thanks

    Earle
     
  6. Wayne A. Pflughaupt

    Joined:
    Aug 5, 1999
    Messages:
    6,061
    Likes Received:
    25
    Location:
    Katy, TX
    Real Name:
    Wayne
    Earl,

    Are your using 12dB/octave slopes on both sides, or just the low pass?

    The method you used to set the sub’s phase control is a good start. However, I found in my system that the phase setting affected interaction up to an octave beyond the crossover point.

    Personally I would be using at least 24dB/octave slopes for both low and high pass, if that is an option. If the sub is close to the mains with that slope, setting the phase for 180 should do nicely.

    Regards,
    Wayne A. Pflughaupt
     
  7. EarleD

    EarleD Supporting Actor

    Joined:
    Aug 27, 2000
    Messages:
    728
    Likes Received:
    3
    OK,

    I set the ICBM to the special sub setting(36db/oct) and it made a huge difference. I set all the ICBM's xover's to 60hz and the dip at 100hz is now just 4-5 db.

    Wayne, the xover slopes are LP=36db/oct and HP=12dboct

    The numbers above have been changed to the uncorrected readings.

    Thanks

    Earle
     

Share This Page