+ Reply to Thread
Results 1 to 2 of 2

Thread: help! Advice for D131/075 system needed

  1. #1
    Junior Member
    Join Date
    Jul 2003
    Posts
    4

    help! Advice for D131/075 system needed

    I'm trying to match an old pair of JBL D131 woofers with a new MR/TW section. The woofers put out nearly 106db at 2.83V. Because of that I think I will be forced to use a horn for MR and TW for efficiency matching reasons.
    The system right now is a D131 with JBL 075 bullet TW and a very old unmarked simple crossover/LPAD.

    Why the change?

    The system's tonal balance not bad; however, the MR lacks clarity and the higher frequencies are irregular.

    Measured in baffle, the 075 produces 94db at 2k, 105/2.5k, peaking at 114/5k, and then dropping: 109/8k, 106/10k, 100/12.5k, 95/16K. Even with an Lpad in the original crossover, you can not achieve a balanced sounding high end. Either the lower treble sounds right and symbols don't or vice versa (you can hear true sounding symbols and the lower treble is too hot).

    Taking both problems together (MR clarity and treble irregularities), it seemed that replacing the 075 with a wide range compression driver might solve two issues at once.

    Any thoughts on this?

    If that's the way to go, is it realistic to assume some of the drivers that claim response 500hz to 20khz really work well over such a wide range? Can I actually achieve the MR clarity and treble performance I'm looking for?

    Advice and driver recommendations are much appreciated!

  2. #2
    Administrator Mr. Widget's Avatar
    Join Date
    Apr 2003
    Location
    San Francisco
    Posts
    8,497
    "... is it realistic to assume some of the drivers that claim response 500hz to 20khz really work well over such a wide range? Can I actually achieve the MR clarity and treble performance I'm looking for? "

    Without some form of active or passive equalization none of the compression drivers that I have tested from Altec, JBL, or Meyer will do 500Hz to 20KHz in a very linear fashion. They won't do 1KHz to 20KHz either.

    Of course with equalization as in the Altec model 19 or the JBL 4430 you can get pretty good response out of them.

    Probably the most linear driver over the range you are interested in is the TAD 4001. I have heard them, but I have not used them in any of my systems. Everyone who has has reported unanimous approval of this driver. The down side is the cost.. they list for about $3,000 a pair.

    The least expensive best alternative is probably using a pair of JBL 2421s which are LE85s with the current diamond surround aluminum diaphragm. You can find beat looking 2420s on eBay and replace the diaphragms with the newer 2421 diaphragms for a fairly economical way to do this.

    The next big thing then is which horn to use... the horn makes a huge difference in the sound quality of the driver. The 2344 is a very nice horn but due to it's constant directivity design it will require EQ. The common JBL exponential horns with the slant plate lens are fairly linear but especially at frequencies below 1200Hz sound like a megaphone to me. They are very affordable though and certainly would be an improvement over your current set up. I would recommend the longer version H92/2312 with an 800Hz crossover. My personal favorite JBL horn is the wooden 2397. It is really designed for a 2" driver though and when I paired them with the LE85 with appropriate adapters I was disappointed in the sound. Now this horn with the TAD would come close to your goal, but we are back to thousands of dollars instead of hundreds.

+ Reply to Thread

Thread Information

Users Browsing this Thread

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

Similar Threads

  1. Electro Voice speaks advice needed asap!
    By whitese in forum General Audio Discussion
    Replies: 7
    Last Post: 06-05-2009, 09:50 AM
  2. List of JBL info
    By Donald in forum Lansing Product General Information
    Replies: 3
    Last Post: 10-27-2004, 05:17 AM
  3. Advice Needed!
    By jsperber in forum Lansing Product General Information
    Replies: 25
    Last Post: 07-16-2004, 07:47 AM
  4. Should I? Advice needed.......
    By Reconer in forum Lansing Product General Information
    Replies: 12
    Last Post: 01-23-2004, 01:06 PM
  5. DIY enclosures - your advice is needed
    By MLVA123 in forum Lansing Product DIY Forum
    Replies: 1
    Last Post: 05-16-2003, 09:16 PM

Posting Permissions

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