Trouble blending in subwoofer, Help!

Discussion in 'Speakers' started by MuneebM, Jun 11, 2004.

  1. MuneebM

    MuneebM Supporting Actor

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    I'm measuring in-room frequency response of my front/primary sub and trying to tweak it to the right level. I don't even want to discuss how much difficulty my rear/secondary sub integration is adding to my HT calibration woes!

    On the note of the front/primary sub (HSU STF-2) calibration, I'm having a hard time getting it well balanced with my front sound stage. I calibrated it to 87 dB using the DVE test tone (DVE test tone is +12 db hot), double-checked the AVR's test tone and it seemed to be good. I have the crossover on the STF-2 disabled and my AVR's crossover set to 80 Hz. I determined that the 180 phase selection on the STF-2 gave me a flatter freq. response as well as a higher SPL with an 80 Hz test tone. I have all my speakers set to small and my LFE/BASS OUT setting in my Yamaha set to SWFR.

    I started watching the RotK DVD and the bass seemed to blend in very well, until I got to the bass-heavy battle scenes! The bass was way too heavy, sounded much too bloated and was practically ringing in my ears! I had to turn down the SWFR speaker level on the Yamaha to -5.0 from 0.0 for it to be reasonable. Turning down the crossover from 80 Hz to 40 Hz helped a little, but I'd rather keep my crossover at 80 Hz. I hate to have to adjust the SWFR speaker level for every movie/scene, so I wanna calibrate/balance it well.

    I have a few questions that I hope the answers can help me better balance my sub:
    - Using the DVE pink noise for LFE, should I be taking into consideration the Rat Shack SPL meter compensation and actually measure the tone 3 dB lower, i.e. 84 dB instead of 87 dB?
    - Is the Avia subwoofer calibration better because it doesn't use an LFE signal but rather uses bass from the main channels?
    - If I use Avia, should I be measuring 85 dB or is the Avia sub test tone mixed too hot or cold?
    - Does my bass sound "bloated" because my crossover of 80 Hz may be too high? Or because my sub is only 10" from the wall? Or neither?

    Sorry for the long post, and I'm sure this has been discussed many times before, but this will really help me and I'm sure other folks that are in the same boat.

    http://66.46.69.23/sigserv/pl/index.pl?p=1
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  2. Wayne A. Pflughaupt

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    Muneeb,

    The problem is that you have hot spots and weak spots in your sub’s response, due to its interaction with the room. You were experiencing the hot spot during the passage of RotK you mentioned.

    This problem will not go away until you equalize your sub. The Behringer Feedback Destroyer digital parametric equalizer will correct these problems and make all frequencies from your sub linear. Here’s a “before and after” response chart that shows the improvement the BFD did for Sonnie Parker, the guy who created of the BFD Comprehensive Set-Up Guide:


    [​IMG]


    I suggest doing a search on this Forum the DIY and Advanced Projects Forum for “Behringer” and “BFD.” You’ll find enough reading material to keep you busy for days.

    Regards,
    Wayne A. Pflughaupt
     
  3. Ned

    Ned Supporting Actor

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    Wayne: The corrected curve rises 13db from 100hz to 20hz. Is that a good "house curve"? Also, do you think he added 13db of boost at 40hz to bring up the dip or was some of it recovered from lessening the adjacent peaks?
     
  4. TimMc

    TimMc Stunt Coordinator

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    Muneeb - yeah, got gotta adjust for the known lower frequency responce curve of the RS meter. Sorry, I don't have the list on this computer but if you search this forum you'll find the freq/db-adj list several places. It does matter and will get you closer.

    And Wayne hit the other point right on the head - if you do a similar graphing you'll probably find all sorts of room reinforcement (and dips). Placement & simple treatments can really do a lot up to a point - after that, if things are still way outta whack & it's bothering you then you need to get serious. A BFD can help tame the beast, and/or you can become a wizard of room treatments. I got really lucky and just had to move the sub two feet along the side wall to fix a big peak - hope your adjusted calibration does the trick for you.
     
  5. BruceD

    BruceD Screenwriter

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    Agreed as well,

    Wayne's advice is probably getting to the heart of your problem. Measuring with your SPL meter and the help of the Excel spreadsheet at the link provided will create a similiar chart for your environment.

    And that second sub placed in the back is likely going to make things worse, it's sure going to make measuring a nightmare.

    Is the second sub the same model as the first? If not, then that's going to really complicate matters as well.

    I'd say you have a bit a work ahead to smoothly integrate your bass response, but that's what this hobby is all about, learning what works for you.

    If you want to try (demo for free) a software measurement tool that also works with your SPL meter, take a peek at the ETF website
     
  6. Richard_M

    Richard_M Second Unit

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    Just to add to the already great information provided.

    My rear sub is at right angles to the front subs, I found this smoothed out the response for me.

    BTW all my subs are front firing, the front 3x face the listening position, but the rear is positioned sideways against the rear wall 1.5 metres behind the listening position firing from right to left looking at the sub.
     
  7. BruceD

    BruceD Screenwriter

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    Richard,

    You might want to talk about your experience (journey) implementing multiple subs.

    Good to hear from you!
     
  8. MuneebM

    MuneebM Supporting Actor

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    Thanks for all the responses guys. The secondary/rear sub is a modded Dayton from partsexpress that has an STF-2 driver in it. I re-calibrated my subs using Avia, as they seemed to be a little hot when calibrated with DVE. Things are better now, but I fear my secondary/rear sub is the one that sounds bloated ever since I juiced it up with the STF-2 driver, I guess the STF-2 driver is too powerful for the Dayton enclosure. The HSU STF-2 that I use up front as my primary subwoofer has blended in very well with my front soundstage... now I just gotta do something about that mutant Dayton!

    http://66.46.69.23/sigserv/pl/index.pl?p=8
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  9. Wayne A. Pflughaupt

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    Richard, is that a seat-of-the-pants evaluation, or have you done some conclusive in-room measurements?
     
  10. Richard_M

    Richard_M Second Unit

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    Bruce & Wayne...

    Sorry about the delay in responding, been very busy of late.

    Basically the problem with my subs they only have 0/180 phase switches, I tested each sub individually, and added them one at a time, using an un-calibrated Behringer ECM-8000 mic with a pre-amp and ETF5 software.

    The rear sub interacted better in room with the other subs also in operation, by being at 90deg from them, I guess the room dimensions came into play as the front 3x are along the front wall, starting in from the corner of a large L shape room, where the rear sub is at the end of one of the legs. BTW all subs are at least 500mm from corners and/or walls. The other issue that came into play was each sub is at a different distance, so delays also caused phase problems. This and the variable phase issues have been fixed since adding the Behringer DCX2496. By using parametric eq's I have managed to smooth out most to the problem freq’s.

    [​IMG]

    I have been trying to get my wife to agree on new house plans so I can get my purpose built room, We have owned the land nearly 2 years, just can't rush some people [​IMG]
     

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