How many of us EQ our SVS?

Discussion in 'Archived Threads 2001-2004' started by ColinM, Dec 17, 2001.

  1. ColinM

    ColinM Cinematographer

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    I just got my 20-39 where it sounds the best. I'm going to let it go that way for a while, but I am always looking forward to that next tweak. Just wondering how many people out there EQ theirs. I haven't got any obvious peaks so far, but I can see that if I had to keep it in it's original spot, I would have a bad hump around 50-60 Hz or so.
    Besides, $99 for another box on the rack ain't bad.
    [​IMG]
     
  2. Kevin C Brown

    Kevin C Brown Producer

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    Colin- Have you measured yet? [​IMG]
    Got to use a test disc with discrete tones a la the Autosounds 2000 disc, the Stryke disc, and others. The sweeps on Avia, along with the Radio Shack meter won't work for accurate determining of peaks and valleys.
    I personally use a Behringer BFD DSP-1100p. There is a slightly newer 1124p out now.
    Don't think you can do this for $100. The new BFD goes for like $130 at www.lentines.com.
    Rane, Symmetrix, Art are all more expensive than that.
    Try to do a search. Lot's of posts lately about this. (That's why I got mine!)
     
  3. Chris Demaree

    Chris Demaree Stunt Coordinator

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    Actually, I am attempting to EQ my 20-39pc right now [​IMG] With the sub in the only availible corner in the room, I have a NASTY peak centered at 55hz. I am going to move it around a bit, take measurements with Spectra+, leave it in the 'best' location then EQ it to taste. It will be interesting to see what the response looks like before and after.
     
  4. Wayne A. Pflughaupt

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    I know people are probably tired of seeing me say this, but there always seems to be someone else who needs to hear it. [​IMG]
    Chris, If you’re getting an equalizer for your sub there is no need to move it around in the room looking for that “magic spot.” That’s for people who don’t have an equalizer. While they may end up with is response they can live with, it comes at the expense of extension and output. Not to mention, the more boundaries the sub can interact with, the more ragged response is. This is because there will be cancellation at specific frequencies relative to the distance the sub is from each boundary. Often you end up with response so ragged it is beyond the “repair” of an equalizer.
    Once you get your EQ do yourself a favor and just put the sub in a corner, if possible the one with the most uninterrupted wall length in each direction. This will excite the maximum number of room modes and realize a gain of 6-9dB, which is effectively double the acoustic output. Another benefit of corner placement is that it minimizes the effect of nulls.
    As you’ve noted, Chris, you’ll have a response peak or two. However, you can easily notch them out with the equalizer, and then you will have it all: The smoothest response, the lowest extension and the highest output.
    Happy Holidays,
    Wayne A. Pflughaupt
     
  5. Bob_M

    Bob_M Stunt Coordinator

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    Wayne,

    >While they may end up with is response they can live with, it comes at the expense of extension and output. <

    Ok I follow you to here.

    >Not to mention, the more boundaries the sub can interact with, the more ragged response is.<

    But I thought you said above they moved it out of the corner to get better responce?

    Is there any good web sites that go into this is more detail? I would really like to know why room dimentions play a big part in freq responce and how you can calulate this.

    Thanks Bob
     
  6. John Morris

    John Morris Guest

    I use a Symetrix 551E to tame some room induced peaks in my SVS Ultra. No room is perfect... but I'd like my music to be... as close as possible.[​IMG]
     
  7. Kevin_W

    Kevin_W Second Unit

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    Colin,

    Do you have a powered or passive model SVS? If passive, you might find the Art 351 that SVS sells very important since it has a subsonic filter in it... it filters out extremely low bass frequencies so that your driver doesnt bottom out trying to reproduce a frequency its not designed to reproduce.

    Kevin
     
  8. Bob Christensen

    Bob Christensen Stunt Coordinator

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    Chris D: What you may be seeing/hearing with your 55 hz spike is a quarter-wave reflection off the ceiling. The quarter-wave length of a 55 hz tone is roughly 60 inches, which, I bet is close to the height of your ceiling above the top port of your sub. You can try to reflect or absorb this by hanging something temporarily above the sub and see if the spike goes down any. This is a “quick and dirty” test only, and you may have to figure out a SAF acceptable alternative, if it proves to work out. Much better than EQ if that is your only problem.
     
  9. Zbigniew

    Zbigniew Stunt Coordinator

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    I am planning to prepare a CD with test tones.

    I will use NCH tone generator to create .wav files.

    Should I use sine, square or any other particular tone shape ?

    How long should each tone be played ?

    _zjt
     
  10. ColinM

    ColinM Cinematographer

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    Kevin -

    I have the passive 20-39 fed by an NHT SA-2, 165w into 4 ohms. Right now it's 12 feet from the corner of a 28 foot wall, with a sofa butted up next to it. Musically it seems dead on when listening to bass guitar riffs and such, so I may not need (IMO) an EQ right now. But the chase is more fun than the catch, so I am always looking for equipment to add, as long as it doesn't detract from the sound. zzsounds.com has the ART for $149, and another 30 step model for as little as $99.

    Just wondering - What are the bottom-most bands on the 30-step ISO spaced EQ?

    How difficult is it to manage a Parametric?

    - CM
     
  11. ColinM

    ColinM Cinematographer

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    And what the heck is Euchre???[​IMG]
     
  12. BryanZ

    BryanZ Screenwriter

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    Not as of yet but I may in the future.
     
  13. Brian Fellmeth

    Brian Fellmeth Supporting Actor

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    Zbig- Sine waves. 8-10 seconds each.
     
  14. BruceD

    BruceD Screenwriter

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    Colin,

    I don't think you want a 30-step ISO spaced EQ for tuning out bass modal peaks in your room.

    I think you would be better off with a parametric EQ, so you can zero in on the center frequency of the bass peak and adjust the "Q" bandwidth of the EQ to exactly match the bandwidth of this peak, thus nullifying it's effect.

    Behringer BFD 1100P parametric EQs are pretty popular on the sub channel only, and I know they have come out with an upgraded model, 1124P, that is said to list for $129 and some have bought for $89.

    BruceD
     
  15. Kevin C Brown

    Kevin C Brown Producer

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    Bruce- The 1100p listed for $200 and could be had new for $160. The newer 1124p lists for $160, and can be had for like $130.
    If you see one for $89... let me know! [​IMG]
     
  16. Wayne A. Pflughaupt

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    Bob M,
    Sorry for the confusion; I can see I was less than clear. I made a lengthy post on this topic a few minutes ago that will explain everything, hopefully very clearly. If also has the link you asked for:
    http://www.hometheaterforum.com/htfo...threadid=32850
    My third post on this thread is the one you want.
    Happy Holidays,
    Wayne A. Pflughaupt
     
  17. Chris Demaree

    Chris Demaree Stunt Coordinator

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    I am using a BFD dsp1124p with a SVS 20-39pc. The sub is in the only availible corner, aproximatly 1/2" from each wall. I was unable to get spectra+ to graph my room response (setup error on my part, i'm sure), so I am using the sub+center freq sweep on AVIA as my source and am making notes of any obvious peaks and/or nulls during the sweep (200hz to 20hz, xover is 80hz,ratshack SPL meter). It looks like my only real 'peak' is centered around 55hz and starts about 5hz in each direction. No really bad nulls, so I should consider myself lucky [​IMG] I set the first filter at 20hz and gave a 3db boost for a 5hz range (12/60ths of an octave)? The second filter is set at 55hz with a -12db cut and larger 'range'. I am still learning how to guess 'range' better, but setting it, then measuring the response seems to work reasonably well. I still have a lot of measuring to do, but am definately making progress. I'm not sure if I should use any kind of 'boost', due to possible clipping, but I read several posts suggesting that setting a bit of boost at the very bottom would sound better than 'flat' response. I will post my final results, once I figure out the which settings I like the most.
    P.S. This forum is incredibly helpful, thanks!
     
  18. Wayne A. Pflughaupt

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    Chris,
    I don’t have the AVIA disc, so help me understand what you’re doing. You mention a “sweep” (frequency sweep, I suppose). My question is, how do you know what frequency is the problem?
    This is the second time I’ve seen “Hertz range” used with the BFD for what should be bandwidth or Q. I find this puzzling, too.
    Regardig the AVIA, Kevin Brown had this to say at this link: http://www.hometheaterforum.com/htfo...threadid=30284
     

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