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cab setup in doorway == mondo virtual enclosure??

Discussion in 'Amps and Cabs [BG]' started by craigb, Mar 26, 2001.


  1. craigb

    craigb Supporting Member

    I'm polling the collective wisdom of the board. Here's the question (with background):

    This weekend we played a party. This was my first gig with my new head/cab setup (instead of my 1x12 combo) and I was looking forward to cranking up the head and seeing how it and the 15 sounded with some watts going (instead of the turned-way-down level necessary for practice). Because of the threat of rain we set our gear up in a couple of doorways leading out to the back yard instead of on the porch/deck. My cab was in a double doorway with one of the guitarist's Marshall 4x12 and the two cabs basically filled the width of the doorway.

    Now instead of getting to turn up I actually had to turn down a little. However the sound was awesome. Deep, rich and great. Much better than it had sounded in the practice room. I was in bass heaven.

    Now I can think of a couple of factors that might have affected things:
    1) it was outside so no room reflections and plenty of space to play into
    2) being in the doorway I had no walls behind the speaker at all - no proximity effect from that (for practice the cab is right against a wall, next to a PA speaker, kind of in a corner)

    or last, and most speculatively (I have no knowledge of the possible physics involved here):

    3) being setup in the doorway made the room act as a "virtual box" for the speaker - massive volume, great frequency response, etc.

    So any comments/info on this type of setup?
     
  2. MikeyD

    MikeyD

    Sep 9, 2000
    The rear volume isn't a factor as far as I can see. If there is a rear-facing port, I could see some effect on the sound in front, though. I think what you have is primarily an "infinite baffle" approximation. You get nice, coherent, quarter-space wavefront development with the sound essentially coming from "the wall". It seems like there would be little in the way of anomalous interference (caused by phase problems from reflections) that you sometimes get when playing near a corner, for example. And you're right - it's propagating into a nice, nearly anechoic environment so you don't get all kinds of silly standing waves that make the response uneven. It probably sounds better (louder) than a cabinet sitting in the middle of an outdoor stage because the wall is helping to confine the sound forward.
    - Mike
     
  3. craigb

    craigb Supporting Member

    Thanks for the info Mike

    It's a front-ported cab (SWR WM-15T). I've been meaning to get some speaker building/design books to better understand how these things operate and go together (and maybe build some for fun).
     
  4. MikeyD

    MikeyD

    Sep 9, 2000
    You're welcome! Yeah - it's really interesting stuff. There are lots of books - and web sites, too.
    - Mike