BFD and Trouble with Different Seating Positions

Discussion in 'Speakers' started by aldamon, Mar 11, 2005.

  1. aldamon

    aldamon Second Unit

    Joined:
    Mar 26, 2002
    Messages:
    297
    Likes Received:
    0
    Well, I got my BFD today and my worst fears have been confirmed. I cannot resolve the tremendous sound differences between the seating positions in my room. I've taken measurements less than 36 inches apart (two different seating positions) and the peaks and dips shift wildly. I have no trouble from 20 - 40, but once I hit 45 I'm screwed. What's a peak and a dip in one spot is reversed or shifted in the other [​IMG] I'm starting to think the BFD might have been a waste of money unless the idea is to create one sweet spot at the expense of my wife's spot.

    [​IMG]

    My sub is an SVS 25-31PCi. Blue is my spot and pink is my wife's spot 3 feet to the right. Things were actually worse than this before, but I tried to average the gaps with the BFD. I haven't used any gains because it looks like the dips in one spot are caused by equal energy being displaced to the other spot. Of course, this makes sense because the SVS is flat at the factory. The energy has to go somewhere.

    [​IMG]

    Any ideas? Are room treatments inexpensive?
     
  2. EdwinK

    EdwinK Agent

    Joined:
    Oct 29, 2004
    Messages:
    38
    Likes Received:
    0
    What you show here is nothing new or dramatic, it is precisely how accoustics work in a given environment. Room-treatment might help you out, or less concern about creating 'ideal' listening conditions at two different locations.

    I would suggest either treating your room (bass-traps, etc), or eliminating annoying peaks at both locations by reducing overall level at that frequency. With careful subwoofer placement and likewise listening positions the frequency graph at both locations can be quite satisfactory.

    Don't go for +/- 2dB 20Hz-100Hz, unless you're prepared to spend a lot of time and money on room treatment. Good luck!
     
  3. Max F

    Max F Second Unit

    Joined:
    Jun 26, 2004
    Messages:
    250
    Likes Received:
    0
    If you're watching movies, don't sweat it! [​IMG]

    You won't really notice any difference between those two spots when something explodes or other room shaking effects. Accuracy is important for music however. You're going to have a sweet spot anyway when listing to stereo out of your front speakers (i.e. imaging), just set up the sub to be flat at that spot - perferably where you (the one that goes through all of the trouble to set this stuff up) are sitting.
     
  4. aldamon

    aldamon Second Unit

    Joined:
    Mar 26, 2002
    Messages:
    297
    Likes Received:
    0
    Fair enough. Am I at least on the right track with the lower frequences? I chose to align everything with 22Hz because that's where my sub really starts to roll off. The BFD really flattened the peak I had around 28 Hz.
     
  5. Phil Iturralde

    Phil Iturralde Screenwriter

    Joined:
    Oct 7, 1998
    Messages:
    1,867
    Likes Received:
    0
    EdwinK & Max F are correct!


    Not really since between the Frequency Range 16Hz to 60 Hz, ... this musical frequency area is where you sense power, and it's felt more than heard.

    Review this 1/3 Octave Frequency Chart - basic guide in the effects of equalizing those octave ranges and it also includes "Key Frequencies For Instruments"

    Now, view the fundamentals of music and voice in the following frequency music chart here. (from the PSB website)

    So, the real question is, ... how does your overall HT sound???

    You've got the sub-sonic bass foundation that can be felt and speakers that are virtually flat between 100 Hz to 10 kHz, ... so based on these charts and your room, just enjoy the full Cinema Theater impact and sound once you're done playing with your BFD!!!

    Phil
     
  6. Brian Fellmeth

    Brian Fellmeth Supporting Actor

    Joined:
    Jul 30, 2000
    Messages:
    789
    Likes Received:
    0


    This is just cruel reality as has been stated. You can only get it perfect in one location. Not only will it be very different 36 inches away (up, down sideways, front back) but a movement of the sub or even the mains (in the tradeoff band) a couple of feet will have a surprizingly large impact on the curve. Even moving a large piece of furnature will change it measureably.
     
  7. aldamon

    aldamon Second Unit

    Joined:
    Mar 26, 2002
    Messages:
    297
    Likes Received:
    0


    Oh, I'm enjoying the SVS. I just don't know if I'm enjoying the BFD [​IMG] Unless flattening out a 5db peak at 28Hz was worth $100. I'm starting to have my doubts.
     
  8. Max F

    Max F Second Unit

    Joined:
    Jun 26, 2004
    Messages:
    250
    Likes Received:
    0
    I would say that if you are just watching movies, then yes the BFD is probably not worth it.

    However, if you like tight bass and not slow or delayed or fat bass for music, then its a wonderful devise especially for these ported subs that seem to have pretty big peaks in room response. Excluding group delay (which i think is not audible) you can have a ported sub, with its extra spl and extension, play as well with music as a sealed sub, IMHO.

    Basically for me, the BFD made a kick drum sound tight and fast like a kick drum should sound. Explosions, i could care less. My previous peaks in room response shook the walls pretty well for movies.
     
  9. EdwinK

    EdwinK Agent

    Joined:
    Oct 29, 2004
    Messages:
    38
    Likes Received:
    0
    It might depend on how many particular adjustments have to be made, but I for one am extremely happy with such a tool - with both music and movies. Listen to a frequency sweep to hear if the difference between having one and having to do without is big enough for you.
     

Share This Page