Jims 3 way speaker build

[jimbones]

Not everyone will share this same view but personally, for a cabinet this size I would be using 25mm all round and I usually go 36mm for the baffle. Not sure what your bracing plan is but I also go for plenty of bracing.

If you are using Baltic birch for the aesthetics consider getting just a 12mm sheet with a sheet of 12mm MDF and layering them together for all the panels. (MDF on the inside obviously).

Should be a lot cheaper than 25mm slabs of birch ply.

I plan to use bracing as opposed to sheer mass. I have a bad back (surgeries) and am not a spring chicken ( how old is a spring chicken anyway?) Therefore I do not plan on using MDF. I agree that the layering would be cheaper, but would also require additional man hours. So if I did do 25mm all around then it would ber a lot less operations and more expensive. May be worth it.
Thank you for your advice I will consider 25mmagainst more bracing.

[jimbones]

Ok so a n adjustment and cabinet dimensions. The 12 inch driver is huge, the flange is 13 1/2 inches so a 14 inch baffle does not leave enough meat on the side. I am increasing the front width 2 inches but leaving the rear dimensions unchanged. Than means I have to reduce the height. More to come

[jimbones]

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

[Wolf]

If you are Matrix bracing that's probably adequate, if you are not it's way way too much accounted for.

Wolf

[jimbones]

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?

[djg]

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.

[djg]

[jimbones]

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..

[rpb]

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.

[Wolf]

Matrix bracing;

https://audioxpress.com/article/speaker-design-driver-induced-vibrations

You aren't using it.
Wolf

[jimbones]

Matrix bracing;

https://audioxpress.com/article/speaker-design-driver-induced-vibrations

You aren't using it.
Wolf

Got it, nope. If I use substantial amount of windowpane brace will that be ok?

[Chris Roemer]

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.

[JRT]

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.

[Wolf]

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

[jimbones]

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.

[jimbones]

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