How's this frequency response? Should I get an EQ for my sub?

Discussion in 'Archived Threads 2001-2004' started by David Ely, Aug 30, 2002.

  1. David Ely

    David Ely Supporting Actor

    Joined:
    Sep 1, 1998
    Messages:
    753
    Likes Received:
    0
    Trophy Points:
    0
    I took some time today and measured from 120Hz to 25Hz in my HT. Here are the values I received.

    Code:
     FreqdB
     
     12073.5
     11973.5
     11873
     11773
     11673
     11573
     11473
     11373
     11272.5
     11172
     11072
     10972
     10872.5
     10772.5
     10672
     10571.5
     10471.5
     10371
     10270
     10169
     10068
     9967.5
     9866
     9765
     9664
     9562.5
     9461
     9361
     9261
     9162
     9063
     8965
     8867
     8768
     8669.5
     8570.5
     8471.5
     8372.5
     8273
     8173
     8073
     7973
     7872
     7771.5
     7670.5
     7569.5
     7469
     7369
     7269
     7169
     7069
     6969
     6869.5
     6770.5
     6671
     6570.5
     6470
     6369.5
     6269
     6169
     6069.5
     5971
     5874
     5778
     5680.5
     5580.5
     5480.5
     5380
     5280
     5180
     5080
     4979.5
     4879
     4779
     4679
     4578.5
     4478.5
     4378.5
     4278
     4178
     4078
     3978
     3877.5
     3775
     3676
     3572.5
     3471.5
     3374
     3278
     3178
     3078.5
     2974
     2870.5
     2768
     2666
     2569
     


    These are uncorrected values taken with the Radio Shack SPL meter and a test CD I made from test tones on the net. I've found the correction values for the SPL meter on the net, but I don't know how to apply them to all these values.

    How does this frequency response look? Would there be a benefit to buying an EQ?

    In case anyone's wondering, this is a Paradigm PW-2200 sub. Receiver's crossover is set to 100Hz.
     
  2. Ned

    Ned Supporting Actor

    Joined:
    Feb 20, 2000
    Messages:
    838
    Likes Received:
    0
    Trophy Points:
    0
    (frankenstein voice)

    numbers bad, graphs good
     
  3. David Ely

    David Ely Supporting Actor

    Joined:
    Sep 1, 1998
    Messages:
    753
    Likes Received:
    0
    Trophy Points:
    0
    Okay ... Let me find a place to host the picture.
     
  4. David Ely

    David Ely Supporting Actor

    Joined:
    Sep 1, 1998
    Messages:
    753
    Likes Received:
    0
    Trophy Points:
    0
  5. Dustin B

    Dustin B Producer

    Joined:
    Mar 10, 2001
    Messages:
    3,126
    Likes Received:
    0
    Trophy Points:
    0
    Yep, I'd say an eq would help you out. Would allow you to pull the portions that are up around 80dB back down to 70dB to get you a nice flat response.

    Try running the tones through 110hz to 80hz with your phase control in different positions and see if that helps the dip around 90hz.

    Don't try and boost that dip with an eq though, as you'll severely limit your subs headroom. Which would be worse than the dip. But hopefully a phase adjustment will make it a smaller dip.
     
  6. David Ely

    David Ely Supporting Actor

    Joined:
    Sep 1, 1998
    Messages:
    753
    Likes Received:
    0
    Trophy Points:
    0
    Ya, I tried difference phase settings. This is really the best I can get. Setting the phase to 180 helps a bit with the dip around 90Hz, but make a larger dip around 60Hz.
     
  7. Ned

    Ned Supporting Actor

    Joined:
    Feb 20, 2000
    Messages:
    838
    Likes Received:
    0
    Trophy Points:
    0
    I'd play around with the sub position first. Also make sure the RS meter is placed right where your head would be in the positions you are measuring. Using a tripod might be a good idea too.
     
  8. Shawn Solar

    Shawn Solar Supporting Actor

    Joined:
    May 12, 2001
    Messages:
    763
    Likes Received:
    0
    Trophy Points:
    0
    IMO a eq will make a world of a difference. Especially in 50-60hz range where bass tends to sound real boomy. I just finish eq'ing my sub and can't imagine listening to it without an eq. 6db sounds subjectively twice as loud so looking at that graph I would use 3bands at least to bring down a couple of areas. I personnally would prefer a dip at 60hz then 90hz. a hole at 90hz will sound more obvious cause thats where it blends with the mains. At 60hz our hearing is less sensitive and tends to smooth bass more.
     
  9. David Ely

    David Ely Supporting Actor

    Joined:
    Sep 1, 1998
    Messages:
    753
    Likes Received:
    0
    Trophy Points:
    0
    I updated my site above with a new graph. It's showing frequency response with the phase at 180.
     
  10. Wayne A. Pflughaupt

    Moderator

    Joined:
    Aug 5, 1999
    Messages:
    6,187
    Likes Received:
    51
    Trophy Points:
    9,110
    Location:
    Katy, TX
    Real Name:
    Wayne
    Experimenting with different placements can be somewhat helpful if you don’t have an equalizer, but once you get one it’s generally best to put the sub in a corner. That will usually give the best extension and SPL level. The response curve might not be ideal, but that’s what the equalizer is for. A parametric equalizer will definitely help this and most other sub installations.

    The phase control should be adjusted with the mains operating, since it compensates for time domain differences between the sub and mains, relative to your listening position. That will make a big difference in your readings (if you were using only the sub before).

    The 94Hz valley is not as big a problem (audibly speaking) as it seems to be. It appears to be fairly broad, but that is due to the non-traditional spacing of your test tones. This valley as actually less than 1/3-octave wide.

    The biggest problem will be the “cliff” between 56 and 60Hz. This situation (a sharp drop with “plateaus” on either side) is difficult to equalize because it doesn’t “fit the shape” of a bandpass filter. Any filter applied to reduce that differential will also affect neighboring frequencies that were fine before equalizing (i.e., the “plateaus”), so other filters will be required to counteract that effect. But it can be eliminated in the end, if enough filters are availiable.

    Regards,
    Wayne A. Pflughaupt
     
  11. Chris Tsutsui

    Chris Tsutsui Screenwriter

    Joined:
    Feb 1, 2002
    Messages:
    1,865
    Likes Received:
    0
    Trophy Points:
    0
    You could try room treatments such as bass traps/helmholtz resonators or wall paneling.

    Take your room a step closer to anechoic and perhaps find that response you're looking for.

    I've been doing some R&D with DIY treatments and will soon have a site up with many pics of How-to make them and HH resonators.
     
  12. Andrew CM

    Andrew CM Extra

    Joined:
    Apr 7, 2000
    Messages:
    21
    Likes Received:
    0
    Trophy Points:
    0
    Sorry this is a little off the thread but
    1. How do u get such a graph?
    2. Is it better to do SPL levels with the other speakers "off"?

    I'm still in the process of doing initial tweaks of my subs using a Rane PE 17 EQ.

    Thanks and happy Labour Day to all my US colleagues.
     

Share This Page