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Thread: 3-way JBL inspired build - 123A - 2420/2307 - supertweeter - DSP crossover

  1. #1
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    3-way JBL inspired build - 123A - 2420/2307 - supertweeter - DSP crossover

    Hello all

    I'll be logging my new project here.
    Parts used will be the JBL 123A - JBL 2420 compression driver and 2307 horn, combined with a supertweeter. Possibly not JBL but a Visaton TL 16H. In which case I'd be crossing over at 1200hz and 7500hz through a DSP.
    Still drawing out the cabinet.. Any tips or input are of course appreciated.

    Best

    Tim

  2. #2
    Administrator Mr. Widget's Avatar
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    Investigate woofer/box tuning. I think if you use a box that is a bit larger than the L100 it would likely be an improvement over the stock L100. I would also bump the tweeter crossover up to 10KHz.


    Widget

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    Quote Originally Posted by Mr. Widget View Post
    Investigate woofer/box tuning. I think if you use a box that is a bit larger than the L100 it would likely be an improvement over the stock L100. I would also bump the tweeter crossover up to 10KHz.


    Widget

    I figured as much. Still drawing things out, but my idea at the moment for cabinet, is a 50% (approximately) downscaled version of the 4343B model which should yield a volume of around 75l. I'm aiming for 65l~ net volume. Still have to model the driver with regards to tuning.

    I'll definitely expirment with the crossovers as well. Since it's all DSP controlled it won't take long at all.

    Best

    Tim

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    So, I've simulated the 123A-1 in a 70l cabinet tuned to 40hz and sealed. I'm doubting the numbers, but if they are correct, that is a 5db bump centered around 60hz and I'm inclined to go sealed here. These will be placed relatively close to a backwall as well. Thoughts?


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  5. #5
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    Was able to source another pair of 2420/2307 in combination with a pair of 2405 tweeters .. So the Visaton tweeters are out and we're going full JBL



    Oh.. And the mint 123A-1 pair I was able to get ..


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    Hello all

    I'm currently cutting the panels for this project.
    For the tweeter and horn cutouts: I'm finding conflicting info. Sizes range from 3 1/16" to 3 3/16" for the tweeter and 4" to 4 1/4" for the 2307 horn.. My question is if someone has the definite answer? I'd like to get it right the first time.

    Best

    Tim

  7. #7
    Senior Member Ian Mackenzie's Avatar
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    Quote Originally Posted by TimVG View Post
    Hello all

    I'm currently cutting the panels for this project.
    For the tweeter and horn cutouts: I'm finding conflicting info. Sizes range from 3 1/16" to 3 3/16" for the tweeter and 4" to 4 1/4" for the 2307 horn.. My question is if someone has the definite answer? I'd like to get it right the first time.

    Best

    Tim
    http://www.audioheritage.org/vbullet...2-Bolt-Pattern

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    I've found certain JBL parts, with the same part numbers, can vary in dimensions. You'd be better off measuring your actual parts and cutting accordingly.

  9. #9
    Senior Member Ian Mackenzie's Avatar
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    I think you will find the template accurate.

    The hole needs to be slightly larger than the diameter of the mouth.

    More important are the location of the holes in the mounting flange

    http://www.audioheritage.org/vbullet...ll=1#post19608

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    Thanks for all the feedback!

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    Got some assembling done.






    Next up is the baffle and back panels, sanding, making sure the whole thing is airtight.. TBC

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    I patinated the plywood enclosures with a mix of vinegar and steel wool.



    Afterwards I put on a grey wash with a brush, and sanded in three steps from coarse to fine with the grey wash still semi wet. This gives a nicer overall look than just using a brush.



    After letting the cabinets sit to dry out completely I once again did some sanding, to bring out the grain.


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    To finish off the cabinets, I'm gonna apply some varnish.

    This gives a nice protective layer, and brings out the contrast between the wood and greywash.


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    Baffles finished in RAL 8019






    Test fit


  15. #15
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    So far so good..


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