GM-416-8B MLTL Corner Cabinet

[srivenkat]

My latest version of the front baffle.

My idea of using flat rings of brass for the bass speaker and the 5"-9" dia. adjustable port grill cloth frames hit a snag. I have figured out that you could cut both rings out of the same piece of flat plate so you would need two for both speaker. A quick search found a place selling 24"x24"x1/8" 260 brass sheets, except the price is $400, so $800 total. They also sell 2'x2'x3/16 3003 aluminum for $30, I suppose it could be painted with a bronze finish.

VolvoHeretic,

Great diagram, thank you. Interesting thought on brass rings, or, I thought of using removable port boards.

Also, for the curved back, I spent more time today trying (smaller boards and logs) on the cuts to make the joints. It is getting simpler, I initially took that as semi-circle and counted the number of boards (# 8) but the 22.5 degree cut (on the edges) didn't align to get the depth (26-1/2) and width. So, each piece edge requires different angle cut to align for this measurement. Not sure whether the CAD diagram can suggest the required angle for each board on both edges.
Now, I am planning to cut different angle edges (15, 22.5, 30 and other sizes) to try to get the right shape. Once I figure out the right angles, things can get better.

Thank you,
Sri

[VolvoHeretic]

VolvoHeretic,

Great diagram, thank you. Interesting thought on brass rings, or, I thought of using removable port boards.

Also, for the curved back, I spent more time today trying (smaller boards and logs) on the cuts to make the joints. It is getting simpler, I initially took that as semi-circle and counted the number of boards (# 8) but the 22.5 degree cut (on the edges) didn't align to get the depth (26-1/2) and width. So, each piece edge requires different angle cut to align for this measurement. Not sure whether the CAD diagram can suggest the required angle for each board on both edges.
Now, I am planning to cut different angle edges (15, 22.5, 30 and other sizes) to try to get the right shape. Once I figure out the right angles, things can get better.

Thank you,
Sri

Sri, the boards are angled 30 deg. from one to the next, so the miter angle for each board edge is half of that or 15 deg.

[srivenkat]

Sri, the boards are angled 30 deg. from one to the next, so the miter angle for each board edge is half of that or 15 deg.

VolvoHertic, Thank you, I will try out today. I will start with the same angle for the parallel boards (6-1/2") ends as well. Also, one thing to note for the cabinet diagram based on GM

"don't forget that the 811 ideally needs to be set back in a recess along with its foam inserts same as the M19's to use its XO, which I didn't see shown"

the M-19 front of the horn has foam around two sides for about ~6-3/8" wide each and ~2" depth (not exact measurement) I couldn't attach the M-19 cabinet plan (it exceeds my current limit). I wonder whether that is something can be considered.

Thank you,
Sri

[srivenkat]

Sri, the boards are angled 30 deg. from one to the next, so the miter angle for each board edge is half of that or 15 deg.

Attaching a sample cut that I tried today, getting there!! Feel comfortable take up the curved design, thanks a lot for helping out.
CurvedSample.jpg start and end (6-1/2") boards didn't align well with 15 deg so I had it with 5 degree but 10 should be fine.

-Sri

[VolvoHeretic]

...didn't align to get the depth (26-1/2) and width. Sri

Sorry Sri, I missed that part of your message, the important measurement you need for the depth is 20", half of the width and the distance from the back of the cabinet to the front most mitered angle. The first panel to the front baffle and perpendicular to it is variable and can be adjusted for Bv volume.

[srivenkat]

Sorry Sri, I missed that part of your message, the important measurement you need for the depth is 20", half of the width and the distance from the back of the cabinet to the front most mitered angle. The first panel to the front baffle and perpendicular to it is variable and can be adjusted for Bv volume.

VolvlHeretic, Thanks a lot. I will try another sample cut with right measurement. -Sri

[Phil-G]

VolvlHeretic, Thanks a lot. I will try another sample cut with right measurement. -Sri

have you considered laminating a panel?

[srivenkat]

have you considered laminating a panel?

Phil-G,

I like to laminate and sure it will look really nice. I'm new to the woodworking and learning the angle cuts now, getting prepared for the actual build once GM finalizes the design/internal details.

Thank you,
Sri

[Phil-G]

it would look nice, but it would also be very strong.

[GM]

have you considered laminating a panel?

Took the words right out of my mouth. All this angle design is good experience, but folks, remember when I noted that with [ML]TLs the primary acoustic pressure was along its axis? This reduces the need for massive walls per se as long as its braced.


Now what is the most rigid, efficient shape? A cylinder. Combine the two and with some bracing along its axis, the wall can be as little as an 1/8" thick if you use a section out of sheet metal, bending wood, an appropriately large diameter cardboard concrete forming/structural tube such as 'Sonotube' or just laminating cardboard sheet over a form.


Anyway, there's myriad ways to do this and don't require fancy tools, etc., so let your imagination/needs decide how you want to do this; leaving bracing as the 'final frontier' and while all this [multiple] angle stuff would seem to be needed if octogon/whatever multiple flat panel construction is desired, the reality is that the easy/lazy/cheap way now that powerful, cheap, thick, adhesives to fill large voids are available in caulk tubes, using dowels or similar of the appropriate diameter for the intended app [closet rod for large cabs is my choice] are the 'no-brainer' way to brace, tie together any angle cylindrical, stepped, slatted, cubic/whatever construction.


GM