Parametric Eq w/ subwoofers

Discussion in 'Speakers' started by Keith M., Sep 2, 2003.

  1. Keith M.

    Keith M. Second Unit

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    Ive done plenty of searches on this subject, but none of the threads discuss the overall outcome good/bad of using a parametric eq with a sub.

    Post your results/findings...Please discuss which unit you are using and why...What did you use to analyze your room acoustics? Test discs, 1/6 vs. 1/3 octave tones, etc...

    Im thinking of going with the ever popular BFD. Seems best bang for the buck and most information available.
     
  2. Andrew Pratt

    Andrew Pratt Producer

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    Keith now that I've got my BFD I don't ever see myself running with out one on my LFE channel. I nmy room I have some rather large dips and peaks that the BFD was able to tame that helpped produce a much smoother less bloated sounding bass. Given the low cost these should almost be mandatory[​IMG]
     
  3. Brian L

    Brian L Cinematographer

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    I consider EQ'ing the sub channel essential to getting correct in-room bass response. Anyone that does not think it is required has perhaps never taken actual in room measurements of their bass response.

    I am not using a parametric at the moment, but am using a AudioControl Bijou with 1/6th octave control below 80 Hz.

    Have you looked over at the the DYI/Advanced section of the forum? Lots and lots of good discussion on the BFD there.

    BGL
     
  4. Ron Alcasid

    Ron Alcasid Stunt Coordinator

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    I am all for using EQ as a last resort. I managed to remove as 20 dB peak from my room just by moving my sub a few feet.
     
  5. MingL

    MingL Stunt Coordinator

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    I'm all for EQ-ing. I can't afford space to experiment with placement. EQ is an automatic decision.

    I use a 1/6 oct RTA to help me dial in the BFD. I tend to use pink/white noise to get me started on the obvious response flaws. I then proceed to using a bass sweep from 10hz to 500hz(the freq range is up to the user to set) for tine tuning and verification.
     
  6. Ron Alcasid

    Ron Alcasid Stunt Coordinator

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    I can think of one disadvantage to using an EQ to tame standing waves. The notch filter cuts the level at all places not just at the spot with the peak. So if you cut a 20 dB peak in one spot of the room in another spot you may be creating a 20 dB dip. That may or may not be a problem depending on your seating.

    An alternative to EQ'ing is room treatment. This involves placing bass traps in strategic locations in the room, though it may get expensive to treat an entire room. I've found one company that sells bass traps for a reasonable price: RealTraps.
     
  7. ChuckRG

    ChuckRG Agent

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    Trust me on this. Never in a million years or with a million bass traps can you tame a 10db or more peak. EQ (or digital room correction) is the ONLY solution (if you can't move the sub)
     
  8. Lew Crippen

    Lew Crippen Executive Producer

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    When my new sub with a built-in parametric (one band) equalizer arrives, I hope to be able to comment. And to comment on the improvement that it made.
     
  9. scott>sau

    scott>sau Stunt Coordinator

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    Keith, Russ Hershellmann one of CEDIAs founding fathers told me in 1995 that using a parametric, or third octave EQ and a RTA helps achive the smoothest response. Asymmetrical placement of multiple subs helps smooth out standing waves and generate a better dynamic range. Matthew Polk beileves in that last comment, but disagrees with equalization. He preaches room acoustics and treatment. I subjectively feel good sound is a balence of all these things.
    Try "My Disc" The Sheffield/Autosound 2000 Test Disc (805-969-4744)tracks 47-56. These tracks contain pink noise that has been filtered into successive 1/3rd octave bands starting at 25Hz. Each track contains three 1/3 octave bands that constitute an octave.
    An o-scope could even help if you want perfection.
     
  10. Greg Bright

    Greg Bright Second Unit

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    Another good CD with test tones is John Janowitz's Stryke's Basszone Test CD available at


    Stryke Subwoofers
     
  11. Doug_B

    Doug_B Screenwriter

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    I use a BFD with the Stryke CD and Ratshack meter to perform the measurements. I can't praise the BFD enough for smoothing out my bass at my listening position. I even direct my 2 channel and multich music to my sub, even though I bypass digital processing (and thus bass mgmt.) on my controller, by utilizing an ICBM.

    Doug
     
  12. BruceD

    BruceD Screenwriter

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  13. Keith M.

    Keith M. Second Unit

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    Id have to agree w/ Bruce about 1/6 octave tones...

    But the often mentioned Stryke CD is nowhere to be found!!! I cant find it on the website or ebay... Anyone have an extra copy? Does it really contain 1/6 tones/sweeps??
     
  14. Brian L

    Brian L Cinematographer

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    OK, I will plug what I used...

    Bass Mekanix 5.0 CD. This has discrete tones in 1/2 hertz increments from 20 to 99 Hz.

    My EQ (AudioControl Bijou) has 1/6th octave control for the sub below 80 Hz. I use the Infinity RABOS meter for measurement, and the Bass Makenix disc for test tones.

    BGL
     
  15. Brian Bunge

    Brian Bunge Producer

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    Keith,

    The last time I talked to John he still had a few of the discs left. He's recently changed over a lot of stuff on his website so you'd probably be better off actually giving him a call to see if he still has any left. I know it has been very helpful for me in the past.

    From here on out I'll be using my laptop as a 1/24 octave RTA! [​IMG]
     
  16. Adam Horak

    Adam Horak Stunt Coordinator

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    I recently EQ'd my 20-39PCi with a BFD and am amazed at the results. My response has improved a great deal. You can check out a thread I started here
     
  17. Brian Bunge

    Brian Bunge Producer

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    Keith,

    I just spoke with John and he said he has a few of the disks left. If you're really interested, give him a call.
     
  18. Wayne A. Pflughaupt

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  19. scott>sau

    scott>sau Stunt Coordinator

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    Russ Hershelmann of CEDIA and Matthew Polk like multiple subs placed asymmetrically, (but Matt does not believe in equalization). I like one in the corner, or stacking two. Doug Osbourne of M&K Professional adives that as well. True, there are isn't gospel to place them these ways. Room size, room shapes and room acoustics are factors to determine best sonics. The key is experimentation.
     
  20. Greg Bright

    Greg Bright Second Unit

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    Herschelmann's latest configuration in the Oct. SGHT shows 4 subs mounted so: front wall center on ceiling, rear wall center on floor, both side walls center at one-half room height. Not really much assymetry here, but I do recall him advocating that at one time.

    And does anybody here actually have their subs arranged this way?
     

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