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Jims 3 way speaker build

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  • jimbones
    replied
    Excited I pick up the wood tomorrow. I came up with an alternate baffle design. Keeps woofer lower in cabinet, will this work as well?
    Attached Files

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  • jimbones
    replied
    Chris Roemer see attached.
    Attached Files

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  • Wolf
    replied
    Column resonance can be a problem too, not that v bracing alleviates it. Bracing all is important.
    Wolf

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  • jimbones
    replied
    Originally posted by Wolf View Post
    The matrix bracing is the second image in the AX link. The translam is not what was intended.

    The equidistant largely rounded edges will still induce more diffraction than 2 different distances with the same edge treatment.
    I would make them same at width and different to the top, rounded or not..

    Wolf
    I was surprised that the article said the vertical bracing was more important

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  • jimbones
    replied
    Originally posted by Chris Roemer View Post
    I figure 0.4 cf taken up by your internal mid "box", and 0.1 cf for a 4" (4-1/2" od ?) x 10" port.
    Magnet would be 3.14 x rad x rad x depth (of magnets/plates "stack"). Add braces.

    Your tweeter center still SEEMs to be equidistant from THREE edges (which is the worst situation you can get). I'd shorten your height (excess baffle height above the tweeter above what you need for a smooth diffraction signature is wasted - IMO), even if you had to widen the rear of the box.
    Chris Roemer I reduced the height by 3 inches, this (1) helps reduce the internal volume which was too high. I did have to widen the front by an inch to give more room for the woofer flange (quite large) (2) addresses the equidistant dimensions.

    Note I am now reducing the volume needed for internals to 0.7 cu ft.

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  • Wolf
    replied
    The matrix bracing is the second image in the AX link. The translam is not what was intended.

    The equidistant largely rounded edges will still induce more diffraction than 2 different distances with the same edge treatment.
    I would make them same at width and different to the top, rounded or not..

    Wolf

    Leave a comment:


  • JRT
    replied
    Originally posted by Chris Roemer View Post
    I figure 0.4 cf taken up by your internal mid "box", and 0.1 cf for a 4" (4-1/2" od ?) x 10" port.
    Magnet would be 3.14 x rad x rad x depth (of magnets/plates "stack"). Add braces.

    Your tweeter center still SEEMs to be equidistant from THREE edges (which is the worst situation you can get). I'd shorten your height (excess baffle height above the tweeter above what you need for a smooth diffraction signature is wasted - IMO), even if you had to widen the rear of the box.
    The baffle is large enough to accomodate large radii at the edges, R4_inch or larger. Large radii at the edges would ameliorate the diffraction ripple above the baffle step. Offsetting the drivers on the baffle does not ameliorate the diffraction ripple, rather just steers the interference ripple problems to other axii.

    The translam matrix bracing that Ben-Wolf has suggested in this thread (in combination with some grinding with a coarse belt sander and some hand sanding) is a good means of accomodating large radii near the tweeter and midrange.

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  • Chris Roemer
    replied
    I figure 0.4 cf taken up by your internal mid "box", and 0.1 cf for a 4" (4-1/2" od ?) x 10" port.
    Magnet would be 3.14 x rad x rad x depth (of magnets/plates "stack"). Add braces.

    Your tweeter center still SEEMs to be equidistant from THREE edges (which is the worst situation you can get). I'd shorten your height (excess baffle height above the tweeter above what you need for a smooth diffraction signature is wasted - IMO), even if you had to widen the rear of the box.

    Leave a comment:


  • jimbones
    replied
    Originally posted by Wolf View Post
    Matrix bracing;
    https://audioxpress.com/article/spea...ced-vibrations

    You aren't using it.
    Wolf
    Got it, nope. If I use substantial amount of windowpane brace will that be ok?

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  • Wolf
    replied
    Matrix bracing;
    https://audioxpress.com/article/spea...ced-vibrations

    You aren't using it.
    Wolf

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  • rpb
    replied
    Originally posted by jimbones View Post
    Question: I am allowing 1.5 cu ft of internal space to be taken up by braces, crossovers, drivers, midrange enclosure, vents etc. Does that seem reasonable I did not do a super scientific estimate. Thank you for your advice
    I don't think that the woofer volume is hurt by being a bit large. If you need to reduce volume though, you can add solid filler.

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  • jimbones
    replied
    OK I'll shoot for no more than 1 cu ft if that seems reasonable. The magnet on the SB34 is huge and then I have amid enclosure of o.25 cu ft internal vol..

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  • djg
    replied
    Click image for larger version  Name:	brace #1.jpg Views:	0 Size:	716.2 KB ID:	1488782 Click image for larger version

Name:	brace#2.jpg
Views:	129
Size:	727.4 KB
ID:	1488783

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  • djg
    commented on 's reply
    Making your windowpane braces from separate pieces instead of taking a big slab and cutting out and discarding most of it is easier and uses much less material.

    1.5 cu ft seems way high to me.

  • jimbones
    replied
    Originally posted by Wolf View Post
    If you are Matrix bracing that's probably adequate, if you are not it's way way too much accounted for.

    Wolf
    I believe what I am doing is matrix bracing, its the same type that Troels uses. It ties in all 4 sides using a single piece of wood and there will be large holes drilled in the wood for air flow. Is that what a matrix is?

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