"Crossover Design for New Project"

[SOOTSHE]

You can/want to jam the drivers within a hair's width of each other to minimize any sonic parallax error and since you're going to run a vertically oriented board brace centered between them (notched as required to clear) to the rear that combined with some other bracing there's no need for a 1" thick baffle.

Right, we want the woofers at the extreme top to minimize the vertical distance between the horn/woofer acoustic centers. The vent will be near/at the bottom.

GM

Sounds like a plan.

[Altec Best]

You can/want to jam the drivers within a hair's width of each other to minimize any sonic parallax error and since you're going to run a vertically oriented board brace centered between them (notched as required to clear) to the rear that combined with some other bracing there's no need for a 1" thick baffle.

Right, we want the woofers at the extreme top to minimize the vertical distance between the horn/woofer acoustic centers. The vent will be near/at the bottom.

GM

Thanks GM, my concerns too are that the max baffle height can only be 60" and as discussed to get to our desired tuning of 30 Hz we had to extend the box(Internal Volume) to 70-74" With 3/4" BB coming in only 5x5 sheets the max height in any direction is going to be 60" one piece.Now the 1" BB comes in 4x8 sheets but is 5 times the cost too unfortuantely.I can get the 3/4" for $39 sheet the 1" is $190 sheet.With the woofers in the horizontal config. will that enable us to shrink the cabinet down a bit.I'm going to do a quick drawing using the paint program then a more 3 dimensional one once I reach the desired Dimensions and configuration. :thankU:

Sounds like a plan.

Yes it Does !! My new measuring equipment is arriving painfully one piece at a time but I'm getting close He-Haw

[GM]

You're welcome!

You lost me........ If the baffle height is 60" max, then how does one extend the internal volume (net Vb) to 70-74"?!

Regardless, I previously noted that since a large baffle needs bracing and cabs usually need some in-room fine tuning, best to make a separate woofer and vent baffle, so 5x5 ft panels are plenty large enough to make the cab from since the side panels need bracing that can double as multiple panel joints.

WRT net Vb, for a given height, width, then obviously the only way to increase it is by increasing depth, though again, Olson's work indicates up to 10.5" regular depth was acceptable, so the theoretical max depth will be a 10.5" o.d. front extension from the wall and the distance from the wall to the corner apex.

Note that room corners around these parts are rarely exactly 90? or perpendicular to the floor, so best to make a cardboard cutout of the ideal size to check at both the floor and at the 60"/whatever height to see what, if any adjustments must be made to the cab's design lest you not be able to slide it all the way in.

GM

[SOOTSHE]

Now the 1" BB comes in 4x8 sheets but is 5 times the cost too unfortuantely.I can get the 3/4" for $39 sheet the 1" is $190 sheet.

Have you considered using double thicknesses of 3/4 ply? I used this method with great results on my LS W bins. I used "Green Glue" between the 2 layers (noiseproofing, adhesive sealant) & it really brought the bottom end alive. This would save on your timber costs & give you a far stiffer cabinet.

[GM]

Why waste the $$$/weight penalty? Minimally braced 19 mm BB or Apple ply is more than adequate to control dual 15"s flexing only a few mm.

GM

[SOOTSHE]

Why waste the $$$/weight penalty? Minimally braced 19 mm BB or Apple ply is more than adequate to control dual 15"s flexing only a few mm.

GM

With all due respect......my experience is all I can pass on & that was that I had my cabs built by a professional cabinet maker who fully understands the design & construction of loudspeaker cabinets. He made them from 3/4 ply & braced the heck out of them.
All I can say is I heard a world of difference when I added the extra layer of 3/4 ply.

[Altec Best]

With all due respect......my experience is all I can pass on & that was that I had my cabs built by a professional cabinet maker who fully understands the design & construction of loudspeaker cabinets. He made them from 3/4 ply & braced the heck out of them.
All I can say is I heard a world of difference when I added the extra layer of 3/4 ply.

This is also one of the benefits of a triangular box as GM said, we can get by with less thickness & bracing with a triangular corner box now I have to find that post about the baffle being 70":doh:

ADDED: @ GM posts 108,103, we discuss a baffle height of 70" to try and get the box to a 30 Hz tuning.I guess the question I was asking does the cabinet have to be as high with the woofers in a horizontal position.If i can go with a height of 60" aand a width of 36" with the 10" setback and then the 24" point where the 2 sides will meet.Should be plenty of Cab.volume. should it not ?? Drawing coming to give better idea of what I'm talking about.

[Altec Best]

This is also one of the benefits of a triangular box as GM said, we can get by with less thickness & bracing with a triangular corner box now I have to find that post about the baffle being 70":doh:

ADDED: @ GM posts 108,103, we discuss a baffle height of 70" to try and get the box to a 30 Hz tuning.I guess the question I was asking does the cabinet have to be as high with the woofers in a horizontal position.If i can go with a height of 60" and a width of 36" with the 10" setback and then the 24" point where the 2 sides will meet.Should be plenty of Cab.volume. should it not ?? Drawing coming to give better idea of what I'm talking about.

Here's the new drawing, will this cab work for my app.If not I'll have to go back to the over/under config.I have ordered the rest of the test equipment so I will be able to give you the driver specs very soon.I really would like to keep it all 3/4 BB as I estimate this cabinet to be at around 225-250 Lbs maybe more. I agree with you on the 1" though I will pay a heavy penalty in weight which I would like to eliminate as much as possible.The horns will definitely have to be in another cab or on a sled to be able to adjust/align them to the woofers.Thanks !!

@ GM BTW I need that list

[GM]

All I can say is I heard a world of difference when I added the extra layer of 3/4 ply.

OK, you're sure he used 11 or 13 lam Baltic Birch, Apple or = no-void plywood? Even the no-void marine grade Pine I used for decades is no longer of sufficient quality IMO. Cabinet grade, while very nice looking, has a MOE approaching MDF plus voids (at least around here). Regardless, I'm in the same position along with numerous others who have posted the same results I've (not) heard, so I leave it to the 'gentle reader' to either make their own choice and/or experiment to find what performs best to them.

BTW, what are the cab's design details? If its bracing doesn't tie all six sides together to ensure it can't 'breathe', I can believe you heard a difference.

GM

[SOOTSHE]

OK, you're sure he used 11 or 13 lam Baltic Birch, Apple or = no-void plywood? Even the no-void marine grade Pine I used for decades is no longer of sufficient quality IMO. Cabinet grade, while very nice looking, has a MOE approaching MDF plus voids (at least around here). Regardless, I'm in the same position along with numerous others who have posted the same results I've (not) heard, so I leave it to the 'gentle reader' to either make their own choice and/or experiment to find what performs best to them.

BTW, what are the cab's design details? If its bracing doesn't tie all six sides together to ensure it can't 'breathe', I can believe you heard a difference.

GM

GM,
I used 18mm ply (furniture grade - veneered both sides) & got bad resonance even with the braces as shown. I put additional 18mm layers on the 2 sides & the back & it transformed the whole speaker.