"Crossover Design for New Project"

[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.

[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

[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

[Panomaniac]

I find a difference with double layer, too. To the ear and to the fingertip and knuckle. I like it. Except for the weight.

[GM]

GM BTW I need that list

Working on it, but it will be closer to the holidays.......

Yeah, my ~20 ft^3 cabs are well braced 3/4" marine ply and I calc them at around 245# and why they have casters and grab handles on the back to move them around ~like a hand truck.

WRT the extra stiffening/damping of thicker panels, maybe Brad will comment on whether he heard any cab 'color'/'tone' from mine. For sure, the thicker panels require less/no bracing, but bracing is so much lighter.

Anyway, nothing wrong with the basic concept, though might as well change the 10" depth to 10.5" to get all the Vb we can, so take some careful corner measurements and work up a more detailed construction sketch to review. If your room's corners are stiff/massive in construction these are going to be able to 'hit' hard in the mid-bass with mids efficiency up there with a flattened A5.

GM

[mah]

On the High Efficiency Speaker Forum there is a current post that, might be of general interest.

[Altec Best]

[quote=GM;1832426]

Working on it, but it will be closer to the holidays.......

Holidays ?? I'll email you we can get them before that.

Anyway, nothing wrong with the basic concept, though might as well change the 10" depth to 10.5" to get all the Vb we can, so take some careful corner measurements and work up a more detailed construction sketch to review. If your room's corners are stiff/massive in construction these are going to be able to 'hit' hard in the mid-bass with mids efficiency up there with a flattened A5.

Great ! Now I have an idea of shape & size I will get cracking on that detailed drawing.Change setback to 10.5" Corners are very stiff, walls are 7-8" thick with very hard thick plaster no sheetrock here. Thanks GM

[quote]

On the High Efficiency Speaker Forum there is a current post that, might be of general interest.

I'll check it out if I can find it you wouldn't have a link would 'ya. Thanks Marshall

[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.

[Earl K]

- Here's a frequency response graph of a GPA 288H on one of their 511E horns ( presently being sold on eBay ) .


<> cheers

[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.

I believe it. Veneered MDF is better than most furniture grade plywood these days based on what's available around here. Still, comparing a folded horn with its much greater acoustic pressure is an 'apples/oranges' comparison to a reflex cab. In its horn gain pass-band, the LaScala is making about as much acoustic pressure as almost four 416 woofers in a sealed cab, so even if made out of the best 19 mm plywood, doubling up the panels on the last third of the horn is easier for most folks than adding the amount of bracing required to keep it from 'flapping in the breeze' like loose lips.

Is the section below it a 'djk' inspired reflex chamber?

GM