Sub placement in corner behind rptv?

Discussion in 'Speakers & Subwoofers' started by Steve Schaffer, May 14, 2003.

  1. Steve Schaffer

    Steve Schaffer Producer

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    I have a Klipsch KSW-12 downward firing sub. I'm very happy with it except that when running low frequency sweeps on AVIA I get low spl meter readings at a couple of places as the frequency dips. I've got my receiver crossover set at 80hz, all speakers small (bookshelf Energys), and the crossover on the sub set at it's max.
    I have tried switching the phase switch on the back of the sub with no real improvement.

    I like my HT sound overall, but am contemplating experimenting with sub placement to see if I can get rid of those "dead spots."

    My HT is arranged corner to corner, with the rptv in one corner. The sub is now next to the right side of the tv takes up all the room between the tv and the wall, with it's front lined up with the front of the tv so the port in the back is at a 45 degree angle to the wall.

    Since it's downward firing, I'm wondering if it's going to be badly muffled if I try putting it in the corner behind the tv?

    I don't really have very many options as far as placing the sub.

    My last experiment with placing it ended up giving the best and flattest response with the sub in the dining area adjacent to my HT room, not a good placement.

    I do have an unused brick-lined fireplace in the right wall and have given some thought to placing the sub there, lol.
     
  2. Chris Tsutsui

    Chris Tsutsui Screenwriter

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    I've worked with a KSW-12 at a friend's house, and the best place I've found is the corner. If you put it in the corner behind the TV it shouldn't be muffled. You could also put it in the front adjacent corner. I predict it may even get louder because it is closer to the corner of the room and get some corner loading (free gain).

    What you can do is move the listening position and sub until the dips are not as noticeable or are relocated to other parts of the room.

    If you want to hear the loudest loud bass, then try standing in the opposite corner. Since it's not practical to sit in the opposite corner watching movies, you have to move around until you are happy with the bass response. My suggestion is try sitting in an area not smack dab between two walls.

    Good luck
     
  3. Bob McElfresh

    Bob McElfresh Producer

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    Corner-loading gives you the most ENHANCEMENT from the walls, but it does cause artificial peaks. Moving the sub along the wall can often smooth things out.

    One technique to find a better spot is:

    Put your sub in your central listening position.

    Disconnect all other speakers and play some bass-heavy tracks.

    Go to the corner and slowly move along the longest wall with a roll of masking tape/6-pack in your hand. By listening carefully, you should find spots along the wall where the bass is boomey/rough, and other spots where it is smoother/quieter. Mark the better positions with tape/can of beer.

    When finished, you should have several potential spots picked out. Relocate the sub to the first/best position and now do your test. If this does not test out better, try the second spot (drinking the beer from each position).

    Eventually, you will find a better position for the sub (or be so drunk, you dont care anymore. [​IMG] )

    If you still have bad peaks at some frequencies, you are a canidate for a device called the "Behring Feedback Destroyer" (BFD) for about $130. This thing is a programmable equalizer that you can basically say:

    Take frequency 44 hz and +/- 3 hz and reduce it by 8 db
    Take frequency 62 hz and +/- 5 hz and reduce it by 3 db
    ...

    This will lower the peaks.

    Search this fourm for "BFD" or "House Curve" to find lots of fellow members who have used this great unit.
     
  4. Steve Schaffer

    Steve Schaffer Producer

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    Thanks Chris and Bob, will play around with this over the weekend. If all else fails I can move everything into an unused bedroom and start over with a less problematic orientation.
     
  5. Brian L

    Brian L Cinematographer

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    IMHO, no matter where the sub is, the in room bass response will likely have some dips and bumps.

    You would be one very lucky man (of have a room that is custom designed by an acoustic engineer) to get flat bass in a room without using some sort of EQ.

    I use a Audio Control Bijoux (1/6 octave below 80Hz), and the bass in my room is far from flat, but much better than without EQ. From what I have read, with enough care and effort, the BFD can give you pool table flat in-room response.

    Had I not spent $1K on the Bijoux (and were happy with the sound), I would definitely get a BFD.

    BGL
     

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