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Thread: Your opinion on 4333 crossover please

  1. #16
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    Interesting... way back in something like 1980 Mark Gander suggested something similar to me. He suggested blocking off the ports and loading the enclosures up with fiberglass. If I remember correctly, Mark was the transducer engineer on the 124/2203 and 136/2231 and Greg was the systems engineer on the L300/4333.

  2. #17
    Senior Member martin2395's Avatar
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    I've seen speakers from Stage Accompany that used "15 JBL units (they introduced their own versions later, sold as SA1503/1513) and every time I saw the inside, they were well stuffed with Rockwool-like material.

  3. #18
    Senior Member audiomagnate's Avatar
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    I did the same thing to my L200's and the improvement is even more dramatic on this older design. IMO, those big empty boxes sound like...big empty boxes. Both designs are attempting to do something they just aren't suited for, produce deep bass, and in the attempt you get a lot of box noise. Relieving them of that task completely and turning it over to modern subs lets them do what they do better than almost any other speaker out there, reproducing music with very low dynamic compression. In addition to damping up the box and ports, rolling off the bass makes them sound better for the well known reason of reduced IM distortion, but you're also not exciting those nasty box resonances in the first place, so it really does clean them up amazingly well. Try it, you'll love it.

  4. #19
    Senior Member ivica's Avatar
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    Quote Originally Posted by 4313B View Post
    Interesting... way back in something like 1980 Mark Gander suggested something similar to me. He suggested blocking off the ports and loading the enclosures up with fiberglass. If I remember correctly, Mark was the transducer engineer on the 124/2203 and 136/2231 and Greg was the systems engineer on the L300/4333.
    Hi 4313B,

    Interesting, some simulation data can show, but due to Xmax, HP filter around 50Hz would be welcome.

    regards
    ivica
    Attached Images Attached Images  

  5. #20
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    Gday,

    well for those that are interested, I made the crossovers and installed them yesterday. My wife and I spent some time listening last night. There is a substantial improvement in that 'in the room' feeling with voices and instruments able to be pinpointed in the soundstage easier. I think my wife said it best when she said 'it's like I'm hearing this for the first time!' About a track we have listened to for twenty years.

    So....my verdict is that the project was a great success, though expensive. The only change I made to the Nelson pass circuit was to use the tweeter circuit from a jbl 4333 crossover that had a 1uf cap in series with a 1.5uf cap, with an inductor between the two to ground.

    Ill try try to create a document with photos etc over the coming weeks that describe the build.

    thanks
    pauly


    Quote Originally Posted by pauly View Post
    Hi all,

    I'd really appreciate some informed comment on the issue of crossovers for 4333 monitors.

    I have speakers configured (physically) as 4333 which have. 2234 woofer, 2420 mid with horn and lense, and slots. Currently they have 3110a crossovers.

    I want to build new crossovers and have purchased the components to build Nelson pass' version of the l300 crossovers.
    -however-
    I was browsing this site and saw an equivilent circuit to the 4333 genuine crossovers that didn't use the tapped inductor.

    Now I have a quandary.The speakers are used to mix music sometimes, and enjoy music ...let's say 40/60%. I use a set of questeds for critical mixing.

    So...I'd really appreciate hearing some informed comment on each of these crossovers, and recommendations on which way to go, particularly from those that have heard or built them.

    Thanks
    Pauly

  6. #21
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    G'day all,

    Here's a document running through my build of the Nelson Pass crossovers.

    Paulys Nelson Pass Crossovers.pdf

    Thanks Pauly

    Quote Originally Posted by pauly View Post
    Gday,

    <SNIP>

    Ill try try to create a document with photos etc over the coming weeks that describe the build.

    thanks
    pauly

  7. #22
    Administrator Mr. Widget's Avatar
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    Quote Originally Posted by pauly View Post
    G'day all,

    Here's a document running through my build of the Nelson Pass crossovers.

    Paulys Nelson Pass Crossovers.pdf

    Thanks Pauly
    Thanks for the write up. I'm not suggesting you do do this, but it would be a very interesting exercise to build a charge coupled version of Nelson's network using more affordable components and compare the two versions.


    Widget

  8. #23
    Senior Member tjm001's Avatar
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    Outstanding documentation! Thank you.

    Just what I needed for my L300-like project. Thanks again.

    Tom

  9. #24
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    Gday tom
    great , I hope it helps. Looking forward to seeing your results.

    pauly,

    Quote Originally Posted by tjm001 View Post
    Just what I needed for my L300-like project. Thanks again.

    Tom

  10. #25
    Senior Member tjm001's Avatar
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    Question about tweeter circuit in the document.

    Quote Originally Posted by pauly View Post
    G'day all,

    Here's a document running through my build of the Nelson Pass crossovers.

    Paulys Nelson Pass Crossovers.pdf

    Thanks Pauly
    Greetings again Pauly. I was reviewing your modified tweeter circuit and saw a possible typo in the text next to Figure 2. In the text you stated you added a 1.8 mh inductor between the capacitors, but Figure 2 shows a .16 mh inductor. Just wondering which one you used. Thanks.

    Tom

  11. #26
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    Thanks for the great write up.

    My own interpretation is that optimising the phase response in the crossover response is the key to getting the best out of this type of two way system.

    Obtaining correct phase response in the crossover region is more important than designing for flatness of response alone without checking the phase response.

    The phase response in this context includes the physical driver offset of the actual acoustic centres and the electrical phase of both the low and high pass filters.

    A test of the correctness of the phase response is to reverse the normal orientation of the woofer and the horn which should yield a steep notch in the acoustic crossover point at the desired listening position.

    When the physical locations of the drivers are fixed subtle adjustment by spreading the crossover points can accomplish this.

    As Nelson points out sometimes compromises need to be made in a commercial design to protect warranty for high power applications but if this is not a key requirement then some refinement can be considered.

    I have always considered the L300 to be one of my favourite JBLs.

    Enjoy.

  12. #27
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    Gday tom,
    Yes I noticed a couple of typos and that's one of them! I actually used a 0.2 mh inductor there as that was the closest I could get.

    thanks
    pauly


    Quote Originally Posted by tjm001 View Post
    Greetings again Pauly. I was reviewing your modified tweeter circuit and saw a possible typo in the text next to Figure 2. In the text you stated you added a 1.8 mh inductor between the capacitors, but Figure 2 shows a .16 mh inductor. Just wondering which one you used. Thanks.

    Tom

  13. #28
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    Gday ian,
    Yes I agree. There's only so much you can do when then horn is sitting back there!
    A long time ago, I experimented with a long throw jbl horn and jbl 12 in low mids, with subs in separate boxes. I put the 12 inch speakers voice coil at the same plane of the horn driver (they lined up vertically), and built a horn box around them, with a 2405 in a phase plug in front of the 12 inch speaker. They sounded sensational. I attributed that to the physical phase coherence of the low mid and horn driver. No need to run out of phase :-)

    thanks
    Pauly


    Quote Originally Posted by Ian Mackenzie View Post
    Thanks for the great write up.

    My own interpretation is that optimising the phase response in the crossover response is the key to getting the best out of this type of two way system.

    Obtaining correct phase response in the crossover region is more important than designing for flatness of response alone without checking the phase response.

    The phase response in this context includes the physical driver offset of the actual acoustic centres and the electrical phase of both the low and high pass filters.

    A test of the correctness of the phase response is to reverse the normal orientation of the woofer and the horn which should yield a steep notch in the acoustic crossover point at the desired listening position.

    When the physical locations of the drivers are fixed subtle adjustment by spreading the crossover points can accomplish this.

    As Nelson points out sometimes compromises need to be made in a commercial design to protect warranty for high power applications but if this is not a key requirement then some refinement can be considered.

    I have always considered the L300 to be one of my favourite JBLs.

    Enjoy.

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