Results 1 to 6 of 6

Thread: Speakers, Crossovers and Measurement for Integration

  1. #1
    Senior Member 1audiohack's Avatar
    Join Date
    Jul 2007
    Location
    Las Vegas Nevada
    Posts
    3,092

    Speakers, Crossovers and Measurement for Integration

    Some years ago I had the good fortune to attend a sound systems, acoustics and measurement class instructed by a very knowledgeable guy by the name of Blair McNair. Blair was the national face of TEF when Crown Audio owned it. Gerald Stanley was the genius at Crown that took the two tables worth of components assembled in Richard Heyser’s basement lab, the original “Nyquist” analyzer and made it a portable measurement system. Whenever the new TEF machine would misbehave in public Blair would carry it into Gerald’s office by the power cord and recite to him how “his child" had embarrassed him in public or simply tell him, "Your child is dead." Blair is a very fun guy.

    One of the projects of our multi day class was loudspeaker measurement, analysis and tuning. Blair had a pair of what he called the world’s most highly modified (......?) monitors as they had a myriad of switches in the back that could bypass any of the passive crossover components and switch the polarity of the two drivers. The system used was a BSS Sound Webb and a Small Crown amp with audio files from a computer.

    One of the exercises was to sweep the drivers individually (without taking them out of course) and then sweep the complete speaker as it was delivered from the factory and determine the crossover slopes and driver polarity, native wide band response etc. He then went on to bypass all the passive parts and created a bi-amp crossover, delay, EQ routine using the BSS Sound Web (forgot the model number). The crossover slopes, splits and EQ was not anything I would have called text book at that point in my studies but this was quite a revelation in what is possible with the right equipment and more than a little knowledge. The difference was stunning; this was unanimously agreed upon by the class via direct comparison of the identical unit beside it.

    It's amazing what is now available in the way of electronic crossovers and system controllers. The instructions elaborate how to use the box and all the things you can do with their magic box but what is equally amazing (at least to me) is the apparent lack of information, at least easily found in depth information on how to really do it. I guess that's not quite true, that would be well beyond the scope of the user manual of such a box. What is really required is a knowledge spanning several disciplines, of measurement systems and methods, transducers and emissions, acoustics and filters.

    The reason I bring all this up is, on Pro Sound Web there is an article, actually the beginning of a promising series that speaks of and for those whose minds respond to the visual, shows how the above subject is accomplished, or at the very least, it is a good primer. The article is in its second part and I would guess should have a couple more parts to come to cover the subject in reasonable detail.

    I know I have much to learn and hope this spurs some conversation.

    All the best.

    http://www.prosoundweb.com/article//...dspeakers_dsp/

    http://www.prosoundweb.com/article//...al_processing/
    If we knew what the hell we were doing, we wouldn't call it research would we.

  2. #2
    Administrator Mr. Widget's Avatar
    Join Date
    Apr 2003
    Location
    San Francisco
    Posts
    9,715
    Interesting but odd... I quickly looked over the article and didn't thoroughly read it, so my question might be answered, but why are they using such "old school" test gear? I realize you used the old TEF gear years ago, but today most would use Smaart in the field or MLSSA, CLIO, or LEAP in more of a Lab setting.


    Widget

  3. #3
    Senior Member grumpy's Avatar
    Join Date
    Oct 2003
    Location
    SoCal
    Posts
    5,739
    I had a warm nostalgic feeling seeing those HP analyzer plots
    Always thought they'd be fun to use for audio. Thanks for the post.

  4. #4
    Senior Member
    Join Date
    Feb 2004
    Location
    Central Coast California
    Posts
    9,042
    Well, grumpy's an initiate in the SoundWeb 4-way quad-amp catechism. I can attest to the dramatic changes that can be made, for good or for ill.
    Out.

  5. #5
    Senior Member 1audiohack's Avatar
    Join Date
    Jul 2007
    Location
    Las Vegas Nevada
    Posts
    3,092
    [QUOTE=Mr. Widget;329317]Interesting but odd... I quickly looked over the article and didn't thoroughly read it, so my question might be answered, but why are they using such "old school" test gear? [QUOTE]

    Quick Thought On FFT Analyzers
    Speed. Yeah baby, that’s it. When you have to wait while an analyzer acquires a trace and then examine it in relation to other traces, the process is slow and tiresome.
    Conversely, when you can move the measurement mic up, down, left and right to your heart’s content, and see the results in virtually real time, you have a tool that allows you to accurately characterize what the loudspeaker is really doing – both on and off axis.
    Speed is everything. It allows you to try numerous changes to your crossovers and related filters, and then view the results immediately. What used to take days with chart recorders or other “static” means of displaying response curves, can now be compressed into hours or even minutes.
    Quote Originally Posted by Mr. Widget View Post
    I realize you used the old TEF gear years ago, but today most would use Smaart in the field or MLSSA, CLIO, or LEAP in more of a Lab setting.
    Widget
    I have LEAP and I use LMS for driver parameter aquisition only, it's painfully slow, the LX500 looks promising but is WAY behind delivery schedule, Iv'e had no exposure to CLIO, a little to MLSSA and SMAART. TEF is MLS capable as well, a great format for post processinig.

    The current hardware generation of TEF, the one I have, is not so old, introduced in 2006 or 2007 I think. A purpose built USB preamp that is PC controlled and it's quite fast. With the ability to run two channels at once while doing this type of exploration I place one mic on axis and one X° off axis and aquire both channels of magnitude and phase at once and on the same screen.

    One of the things I like about the article is the fact that it is not done in a lab, its more like how I would have to do it. Crossover and integration has been my focus of study for some time now, and probably will be for a good while. What a consuming hobby this is!
    Attached Images Attached Images   
    If we knew what the hell we were doing, we wouldn't call it research would we.

  6. #6
    Obsolete
    Join Date
    Apr 2003
    Location
    NLA
    Posts
    12,193
    One of the things I like about the article is the fact that it is not done in a lab, its more like how I would have to do it.
    True.

Thread Information

Users Browsing this Thread

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

Similar Threads

  1. The King of speakers measurement.
    By ginetto61 in forum General Audio Discussion
    Replies: 7
    Last Post: 09-17-2011, 01:36 PM
  2. Subwoofwer Integration
    By Robh3606 in forum Lansing Product Technical Help
    Replies: 7
    Last Post: 09-29-2003, 10:01 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
  •