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Thread: Pieceing together a JBL 4350 build in Australia

  1. #61
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    So I'm back at it hoping to have these speakers up and running in a week or two. Before I go drilling holes I just want to make sure I am on the right path orientating the cabinets 90 degrees and vertically aligning the compression driver and tweeter above the mid-bass. The factory centre points show the mid-bass about 13" from the compression driver, with my lay out it's about 12". Is 1" going to make a difference at all. The tweeter/compression driver spacing is the same as factory.

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  2. #62
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    One other question, is a bad idea to use the mid-bass dog box to support the compression driver? It's going to sit about 10mm above it and I was thinking of packing sorbothane or something underneath to help support the driver. Unsure if the dogbox resonates significantly but could this pose a problem?

    Update:

    May have hit a permanent roadblock to mounting the drivers vertically. These cabinets are 1" thick and the horn is designed to mount up to a 3/4" baffle, as it stands the horn will be 1/4" behind the baffle unable to flush mount. There is a bit of room to work inside the woofer opening but no way could you complete a 360 degree revolution with a router to recess it, the dog box is in the road. I may just have to run them as factory?

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  3. #63
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    No reason to avoid using the mid bass back box to support the horn driver assuming the box is solidly mounted to the enclosure. A 45* chamfer around the front of the horn mounting hole would continue the horn flare with negligible effect on the response, simply enlarging the mouth area.

  4. #64
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    Closer is better from a phase coherence perspective. The change might very make a tiny change in response at some listening angles from a stock cabinet that might be offset with minuscule changes in a passive crossover but itís pretty small potatoís

  5. #65
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    Quote Originally Posted by Riley Casey View Post
    No reason to avoid using the mid bass back box to support the horn driver assuming the box is solidly mounted to the enclosure. A 45* chamfer around the front of the horn mounting hole would continue the horn flare with negligible effect on the response, simply enlarging the mouth area.
    That is a fantastic idea, I will chamfer baffle to throat.

    Another drama with the thicker baffle, the tweeter is flush with the baffle now, is this a massive issue? This is turning into a headache.

  6. #66
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    This 1" baffle is baffling me. Just looking at photos and all the 4343b's seem to have the tweeter flush mounted? Surely that would make a difference?


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  7. #67
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    Quote Originally Posted by kelossus View Post
    That is a fantastic idea, I will chamfer baffle to throat.

    Another drama with the thicker baffle, the tweeter is flush with the baffle now, is this a massive issue? This is turning into a headache.

    If you chamfer the baffle to the throat, the lens is going to leave a notable gap at the top and bottom, though I don't know if you would hear a difference. Is there a way to router down the inside of the cabinet 1/4" where the horn mounts flush?

    Obviously, this can be/is done.


  8. #68
    Senior Member Ian Mackenzie's Avatar
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    I would use the dog box to support the driver. Itís just to take some stress off the baffle.

    The difference in spacing is not a major issue. What you will find is that the vertical orientation might need your listening height will need some working out.

    Same with the slot.

    The slot and the horn have really narrow vertical dispersion at the crossover point. I would suggest you sit as far back as practical to minimise the angle between the slot and the horn.

    With the baffle thickness try rounding off the 1/4 inch with a smooth file until you get a smooth continuation of the horn mouth. Even a flat bevel is unlikely to be a problem.

    You can measure the horn up with REW and look at that.

  9. #69
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    Quote Originally Posted by toddalin View Post
    If you chamfer the baffle to the throat, the lens is going to leave a notable gap at the top and bottom, though I don't know if you would hear a difference. Is there a way to router down the inside of the cabinet 1/4" where the horn mounts flush?

    Obviously, this can be/is done.
    Yeah it will leave a gap, that is a bit annoying but I can't see a way around it. With the dog box so close you couldn't get a router in to do the bottom portion of the recess.

  10. #70
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    Quote Originally Posted by Ian Mackenzie View Post
    I would use the dog box to support the driver. Itís just to take some stress off the baffle.

    The difference in spacing is not a major issue. What you will find is that the vertical orientation might need your listening height will need some working out.

    Same with the slot.

    The slot and the horn have really narrow vertical dispersion at the crossover point. I would suggest you sit as far back as practical to minimise the angle between the slot and the horn.

    With the baffle thickness try rounding off the 1/4 inch with a smooth file until you get a smooth continuation of the horn mouth. Even a flat bevel is unlikely to be a problem.

    You can measure the horn up with REW and look at that.
    I just measured the listening height, ear height will be roughly between the tweeter and horn. I usually sit around 3 to 3.5m from the speakers. My room isn't overly wide so I can't sit much further back than that.

  11. #71
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    So driver cut outs are complete and a dry fit done. All good. I ended up using a round-over bit for the horn. I can always file it down to a chamfer if need be. Unsure if I should paint the routed section blue or black? I thought at first black might help conceal it as I am using a H91 rather than a 2311.

    Pre paint completed with all dents and holes filled, I should be able to sand and get a coat of paint on tomorrow.
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  12. #72
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    Refoamed 4x of my NOS 2235H's today. Easiest refoam job I have had to do, the old foam pretty much fell off. A quick scrape and clean with a solvent and it was good to go. Maybe 2 hours in total, if that?

    Baffles are painted with what I believe to be an extremely close colour match. The ubiquitous RAL5007 is nothing close to the original colour, at least not what they mix here in Australia. That being said whenever I have browsed photos of the RAL5007 on baffles it never looks close either.

    All that's left is to cut and paint backing plates for the unused horn and tweeter cut outs and wire in the crossovers.

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  13. #73
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  14. #74
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    HOOWHAAA!!

    Barry.
    If we knew what the hell we were doing, we wouldn't call it research would we.

  15. #75
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    Congratulations!

    Dang those are massive... they look even bigger on their sides!
    How do they sound? I imagine the low end will be different, perhaps even better.


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