Passive Radiator distance to boundary

Discussion in 'Archived Threads 2001-2004' started by Gil D, Feb 28, 2002.

  1. Gil D

    Gil D Supporting Actor

    Joined:
    Mar 15, 1999
    Messages:
    577
    Likes Received:
    0
    Trophy Points:
    0
    I am interested in a monitor speaker (SF Electa Amator II) that utilizes a passive radiator in the rear but am reluctant to try it since I need to place this speaker 1-2ft from the back wall. The speakers actually need to be set up in a corner of the room and the back of the speaker would be angled towards the rear wall about 5-6 feet from the corner. A sonusub occupies the corner of course.

    I was wondering what the experience of the speaker/sub builder's with using passive radiators and boundary position. Do you think a foot or two distance is just going to result in a boomy and unlistenable speaker?

    Thanks,

    Gil
     
  2. Greg Monfort

    Greg Monfort Supporting Actor

    Joined:
    May 30, 2000
    Messages:
    884
    Likes Received:
    0
    Trophy Points:
    0
    It depends on the cab's tuning. If it's a bit boomy, you can always add some mass to the PR to lower it.

    GM
     
  3. Gil D

    Gil D Supporting Actor

    Joined:
    Mar 15, 1999
    Messages:
    577
    Likes Received:
    0
    Trophy Points:
    0
    Greg,

    I have no idea on the cabinet's tuning. I could probably take a guess at internal volume and try to find out what the PR is to try to get the parameters. But what would I do then?

    Also, how could I add mass to the PR w/out defacing or deforming it? It sounds like a good idea. I have stuffed the ports on some B&W speakers in the past to tone down the bass boom with success.

    Gil
     
  4. Greg Monfort

    Greg Monfort Supporting Actor

    Joined:
    May 30, 2000
    Messages:
    884
    Likes Received:
    0
    Trophy Points:
    0
    Doesn't matter. Either it sounds boomy or not. I'm not familiar with this speaker, but every PR I've seen was made such that weight could be added to the rear of it, so assuming you don't know the parameters then you may have to remove/install it several times until you get the added mass right. Of course measure the amounts as you go so you'll know how much to add to the others.

    Screwing on weight if the PR is a wood disc or gluing on flattened lead fishing weights (or whatever) if a drone cone, etc., just be sure to spread the weight around evenly so it won't 'cock' at high excursions.

    Also, be forewarned that if you should wind up having to tune it appreciably lower it may bottom out if fed a high power low signal.

    GM
     
  5. Greg_R

    Greg_R Screenwriter

    Joined:
    Apr 9, 2000
    Messages:
    1,996
    Likes Received:
    0
    Trophy Points:
    0
    Location:
    Portland, OR
    Real Name:
    Greg
    ALL speakers are going to have a problem being that close to the front wall. I've always considered 3ft minimum distance (unless it's a subwoofer). You have two issues here: the room acoustics (& placement) and the design of the speaker. Consider absorbtion material on the front wall behind the speaker...
     

Share This Page