Results 1 to 2 of 2

Thread: Knocked His Block Off

  1. #1
    Senior Member
    Join Date
    Jul 2003
    Location
    Orange County, CA
    Posts
    3,597

    Knocked His Block Off

    The Mermans do females great, but there is a suck-out at 250 Hz, with a dip below and peaks above and below the dip that affects male voices. I attribute most of this to the cabinets that are made of plywood, have little bracing, and no insulation. I can move the cabinets about the room and the suck-out (measured in the near field) persists.

    I can rap on the box and see this same resonant pattern on the RTA with the mic held against the cabinet. And, the L300s don't have this suck-out, so it is not the room.

    So, I am improving the boxes. The first step is to get rid of the handles. These are thin aluminum and "ring" when rapped. Contrary, to the logo, they are not JBL.

    I designed block-off plates in CAD and cut them out of 5mm smoked acrylic on a laser cutter. This just fills the handle's recess.

    I haven't done any testing yet, and will probably back the acrylic panels with acoustic foam when I do the insides.


  2. #2
    Senior Member
    Join Date
    Jul 2003
    Location
    Orange County, CA
    Posts
    3,597
    No real noticable difference on the RTA. (Maybe 1 dBA reduction between the suck-out and peak.)


    But the increased cabinet volume, though small, would help and there is the possiblility/probability/reality that the handles produced some ringing that can heard rather than measured with an RTA. Other measurement techniques may account for ringing.

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Similar Threads

  1. Be the first on the block to own this
    By DavidF in forum General Audio Discussion
    Replies: 2
    Last Post: 01-24-2010, 06:42 PM
  2. Block ports
    By leif in forum Lansing Product General Information
    Replies: 11
    Last Post: 07-16-2007, 11:17 AM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •