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Waterfalls: gating and other parameters

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  • Waterfalls: gating and other parameters

    How does everyone set this up? I would like to measure some speakers and was playing around with this yesterday without much in the way of consistency!
    This plot is a design I just started working on, but the waterfall plot of my room does not look much different (I didn't save one of just the quiet room, but the bloom from 1.2k up and out is there and fairly similar):

    Click image for larger version

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    Just trying to find out if most of that is my room, my mic is out of whack (I still need to send it in as it is an alphanumeric one) or if I am doing something wrong?


  • #2
    Re: Waterfalls: gating and other parameters

    Before anybody can tell you if you set it up proper, we need to know a little more about the room. What is the approximate size, what kinds of surfaces do you have (EG bare walls, carpet, glass). If your room seems overly live and reflective, you probably did it right.


    • #3
      Re: Waterfalls: gating and other parameters

      Thanks for responding!
      I did move the mic around a bit a few days ago and found that when moved away from the wall (24" or more) the forward sweep that begins just over 1k seems much less severe with ambient noise than with the mic @ 12" from the wall (rough ear distance). I also tried propping a pillow up on the top of the sofa, and right behind the mic...this also made a large difference in both ambient and test tone measurement (I didn't save anything though).
      Room is 12'6" x 12'6" and ceiling is 8'3". Floor is hardwood with Oriental rug that covers @ 80%.
      Two good size cloth sofas forming an "L" along rear and left walls (remaining open space on left wall is a door opening to another room and no door).
      Left wall has a few small pictures at random places.
      Right side wall has 2 windows with Roman shades and cast iron radiators below each. 2' x 2' framed picture between windows, and sub on floor roughly centered.
      Rear wall has 1 - 2' x 3' picture centered above sofa and PJ hanging roughly centered @ 12 below ceiling
      Front wall is a 104" screen with open doorway to "front hall" (just a 3' x 3' area)

      No wall, ceiling or corner treatment and "clap test" yields a slight echo.

      At this point I am leaning toward mic placement and room issues causing what I saw in my original sweeps. My goal was to measure "in room" response with mic at roughly where my head is at listening position. I am going to make some absorption panels and try different placements to see what the effect will be. I suspect this will help a bit based on my "pillow testing"!


      • #4
        Re: Waterfalls: gating and other parameters

        Just got around to trying this in a really live room -- hardwood and plaster and not much else. FWIW.
        Attached Files


        • #5
          Re: Waterfalls: gating and other parameters

          The gate depends on what you want to measure.
          Measure the speaker as such:
          rise the speaker to 4 feet and have it at least 4 feet from backwall and side wall. Put the mic about 3 feet in front of the speaker and measure. The sound from the speaker will reach the mic in about 3 ms and reflections comes from various surfaces comes after 8ms or so. So in in those about 5 ms you have a reflection free room to measure the loudspeaker. How severe the reflections later on is depends on the surfaces reflectiveness of that particular frequency.

          If you want to have the measurement of what you have at listening positions, then you will have to have speakers and room set up as regular and measure. But this really then reflect the speaker/room system not the intrinsic waterfall performance of the speakers.