GM-416-8B MLTL Corner Cabinet

[srivenkat]

Sri, the horn recess is there according to the dimensions GM asked for. Here is a view with everything included, I will split up the sections into details after everything is finalized. Right now, I am figuring two layers of 3/8" bending plywood, and will alter it if I am directed to do so.

VolvoHeretic,

Thanks a lot.

From Model 19, I meant after recessing horns there is opening to place the foam left, right, top & bottom. Please refer the picture in this link, Replacement foam for 2 Altec Lansing model 19 horns | eBay. May be I am missing, just to be sure.

For the vertical bracing, if we choose wooden dowel - is there a size (1"?) recommendation?


-Sri

[GM]

For the vertical bracing, if we choose wooden dowel - is there a size (1"?) recommendation?

Use to be 1.25", so a teeny tiny upgrade:

https://www.menards.com/main/doors-w...27532532607773


GM

[VolvoHeretic]

Thanks for pointing out the flaw in the horn area, here is the corrected version. I don't really like having just a 3/4" board at the top of the horn area, can we drop the horn down another 3/4" and have a 1-1/2" reveal at the top?

I also reduced the number of vertical braces and only used one layer of 3/8" bending plywood

[GM]

The woofer was set in a room mode peak, acceptable cab offset and the horn at the M19's spacing since he's using its XO, so no from a technical POV, but it's his speakers.........

Haven't gotten around to writing misc. final thoughts yet, but one is that the top plate ideally would be double thickness, whether one recessed inside or added to the top or a massive removable one such as marble, so something for him to factor in the decision.

GM

PS: great work BTW, do I dare ask how long it took?

[srivenkat]

Thanks for pointing out the flaw in the horn area, here is the corrected version. I don't really like having just a 3/4" board at the top of the horn area, can we drop the horn down another 3/4" and have a 1-1/2" reveal at the top?

I also reduced the number of vertical braces and only used one layer of 3/8" bending plywood

Thank you VolvoHeretic.

As GM suggested I will double up the top so, it will give the 1-1/2". I will look for the marble option, need to find out the cutting options to the curved or full-round shape.

Just to understand, is there any advantage in having one vs two layers of 3/8" ply?

From my little try out, I am leaning towards your curved design (with 3/4" cuts) but, I will be exploring the 3/8" ply this week to make the final call.

One other thing, there are two vents for 5"-9" per cabinet. I will go thru the brass ring option but i thought of using removable boards of different sizes with neoprene gasket.

Thanks a lot for the great drawings.

-Sri

[VolvoHeretic]

PS: great work BTW, do I dare ask how long it took?

Thanks. Well, I don't really know, I have been working on it while laying on the couch watching TV using my dandy Walmart adjustable roll around laptop stand that I modified to get just low enough to clear my fat stomach. I might have 24 hours so far, but that includes drawing the 416-8b, 802-8G, & 811B horn. I have the 416 drawn in 3D and am trying to figure out how I will draw the 811B which will include revolving the horn shape profile and then removing everything that doesn't belong, kind of like sculpting. It won't be prefect, but will look good from across the room.

When the design is pretty much set, I want to draw everything in 3D. This is a lot different than drawing I beams, but I will be ready for my corner speakers.

The key to designing is NEVER erase anything or alter anything such that you can't return to an older idea. I just copy what is usable and move over and continue on. This projects drawing space is about 100'x100'.

- - - Updated - - -

Thank you VolvoHeretic.

As GM suggested I will double up the top so, it will give the 1-1/2". I will look for the marble option, need to find out the cutting options to the curved or full-round shape.

Just to understand, is there any advantage in having one vs two layers of 3/8" ply?

From my little try out, I am leaning towards your curved design (with 3/4" cuts) but, I will be exploring the 3/8" ply this week to make the final call.

One other thing, there are two vents for 5"-9" per cabinet. I will go thru the brass ring option but i thought of using removable boards of different sizes with neoprene gasket.

Thanks a lot for the great drawings.

-Sri

Thanks for that information Sri, I think you mean between faceted and curved round back. As I understand it, an arc is always stronger than a flat surface, so you might be able to get away with 3/8" although that bending plywood sure looks limp. I would still always use 3/4" plywood bracing to help ensure a straight brace, it will be crucial to build these things square and true with NO racking or it will turn into a disaster quick.

I will try an figure out a build sequence later, but I am leaning towards a removable secondary baffle attached to the base and top and work back from both sides. Once everything goes well, it can be removed to finish the interior of the cabinet, and then permanently attached. Over that would go the finished baffle board.

I am hoping that the speaker front will be a nice veneer of wood and not just an ugly giant grill cloth stretched over everything.

We could make the detachable port board rectangular to match the horn, we just need some attractive seam cover to hide the joints. I suppose the entire front baffle could be detachable and could be attache to the speaker around the edges, but we would need to make sure nothing rattles at the sound decibels you will be able to achieve.

Since these speakers a designed to be rotatable, we should come up with a turntable for both linked together with belts and pulleys such that they will both always be in unison and aimed at the center of the room. Otherwise you will have to have permanent lasers installed to help with aiming.

[srivenkat]

Thanks for that information Sri, I think you mean between faceted and curved round back. As I understand it, an arc is always stronger than a flat surface, so you might be able to get away with 3/8" although that bending plywood sure looks limp. I would still always use 3/4" plywood bracing to help ensure a straight brace, it will be crucial to build these things square and true with NO racking or it will turn into a disaster quick.

I am hoping that the speaker front will be a nice veneer of wood and not just an ugly giant grill cloth stretched over everything.

We could make the detachable port board rectangular to match the horn, we just need some attractive seam cover to hide the joints. I suppose the entire front baffle could be detachable and could be attache to the speaker around the edges, but we would need to make sure nothing rattles at the sound decibels you will be able to achieve.

Since these speakers a designed to be rotatable, we should come up with a turntable for both linked together with belts and pulleys such that they will both always be in unison and aimed at the center of the room. Otherwise you will have to have permanent lasers installed to help with aiming.

VolvoHeretic,

Yes, I meant the faceted (Octagon) shaped one, your drawings helped me immensely. I am leaning towards the Octagon than the bending ply option.

For the Octagon shaped, for vertical braces (7 of them) I am thinking of using either the 2" pine or 1.25" wooden dowel. I am planning to finish with nice veneer front and if possible all sides.

From GM's suggestion, I like to have the entire front baffle removable also, the port removable (nice idea to have an attractive seam). This front baffle removable enables me to use this cabinet for dual 416 drivers in the future, where the bigger horn (511B) will be used on top of the cabinet and with different crossover or a 604.

I love your idea of the turntable

Thank you,
Sri

[jocelys1]

Greg, could you please help understand whether lining up the acoustic centre matters here.

[GM]

???? This is an M19 system, which is aligned.

GM

[srivenkat]

Thanks Sri, with 26.5" depth, I get exactly 24.39 cu ft. I just need to know what the volume of the 811B is.

GM/VolvoHeretic,

I made up my mind to go with Octagon design unless you all think otherwise. Early next week I will have an opportunity to get some ply so, I will start on that part - lumber mart caries only 5X5 sheets but I can get 4X8 from HD or Lowe's. I can get 1-5/16" dowel for bracing miter joints and go for the right bracing/insulation inside once GM finalizes.

Glue choice - PL400/Titebond Wood Glue. Silicone Sealant?

Gasket - Neoprene - any particular size? For keeping front baffle removable, should I have this on both front baffle and the inside frame?

I assume any wooden screws will do fine.

The top/bottom board

From VolvoHertic - "The top and bottom panels if made with just a single sheet of plywood should have a 1/4"x3/4" rabbet routed in so that the side panels have something to lean against. You could also make the base and cap out of two layers with the outer most being full dimension and the second being 3/4" smaller and that could be made out of mdf."

Is it required to have either rabbet round or the additional 3/4" smaller board inside? Anyways the top/bottom board will be screwed/glued on the side panels. If required, I think additional 3/4" smaller board inside sounds like a good option.

I can get started on these initial steps.

Thank you,
Sri