"Crossover Design for New Project"

[GM]

Welcome back GM.

Is it? Maybe it will do 500Hz, but is it best?

Still, from a practical standpoint, it would be nice to hear/measure how much lower the 1.4" 511 will play than the 1" version. Or if it's better toward the low end of the range. What was the 511E made for? Better power handling? Or something else?

Thanks! Good to be back, temporary as it is.

'Best' is app dependent, but ignoring the loss of some of the 511's HF conic horn initial 'fast' expansion, shortening it and bolting on a 1.4" exit driver with its ~1.96x larger radiating area (Sd) is acoustically no different than taking a point source driver horn with a 1:1 CR throat (St) and cutting it off where it has expanded to (1.96 x St) and mounted two of its drivers, i.e. you're substituting increased driver radiating area (Sd) and greater power handling (Pe) for the longer horn's acoustic efficiency.

In theory then, it won't play any lower or at a higher SPL for a given distortion level, but in the horn's 'sweet' BW where its axial length is 1/2 WL long it has 4x (+6 dB) the power handling (dynamic headroom) or 1/4? the distortion or some mean between the two compared to the 511/802.

It seems reasonable to me then that anyone that falls into the group that considers a 511/802/500 Hz XO combo as too harsh/whatever for HIFI apps will probably feel the same about the 511/288/500 Hz XO combo.

WRT horn induced distortion, short of using an optimized WG and all of its performance trade-offs, I believe in acoustic solutions to acoustic problems, so 'giving away the farm' so to speak to solve some relatively minor real or perceived sonic shortcoming is too high a 'price' for me personally.

My SWAG is that it was cobbled together mostly to compete with the rapidly escalating power 'war' which still shows no signs of abating even at this late date.

GM

[bfish]

...long ago I worked out 'close enough' (for me anyway) polar matching XOs and came to the conclusion that dual horizontally opposed 15" drivers were a better match to a 511/500 Hz than vertically...

Based only on the DI plot for vertical 15s below, it appears the opposite to me. At 500Hz, the woofs are at 60 degrees (vertically, which becomes horizontal if you flip them)...

IOW, all else equal, going 'wide' dictates a lower XO point...
GM

I'm not getting it. Not trying to be obstinate, just trying to understand.

[bfish]

... when I measured all the horns and drivers I have, I see the 2nd harmonic shoot up fast under a certain frequency ...

Just curious why you attribute that to the horn instead of the driver?

[GM]

Understood, when I saw that plot I could see it coming round the bend........... Frankly, I think the plot is another of those many marketing errors we found/joked about some years ago, but will take another look at it when I'm not so preoccupied.

GM

[Altec Best]

Thanks, though for me, getting 'well' these days means not feeling as bad as the day before.

:thankU: GM for your advice, and I'm so glad to see you are feeling better today than yesterday !!!!!! :2thumbsup:

My problem though is space. The speakers are going in the corners.So horizontal woofer placement isn't an option, baffle (Too Large), but I can go to the ceiling though .They have to be stacked,I was thinking of building individual boxes or with the separation in the middle of one box with each woofer having it's own vent and the back corners cut off for corner placement.Thanks Again !!

Nice to see you back on the board :coffeedrinker:

[Panomaniac]

Just curious why you attribute that to the horn instead of the driver?

'cause it followed the horns and waveguides, not the drivers.
The drivers must certainly have their own limitations, but what I was seeing seemed closely linked to the size of the horn mouth - even with different drivers.

I'll try to do some more definitive testing.

[GM]

My problem though is space.

Nice to see you back on the board

You're welcome!

Thanks! Unfortunately I had to work on the truck today, so now I'm loaded to the gills with NSAIDs just to be able to sit here, so not looking forward to tomorrow.

OK, what's the widest baffle you can tolerate? I mean it's got to be at least wide enough to get enough depth for the horn. Anyway, yeah, a stackable three box MTM seems like a plan.

GM

[Altec Best]

You're welcome!

Thanks! Unfortunately I had to work on the truck today, so now I'm loaded to the gills with NSAIDs just to be able to sit here, so not looking forward to tomorrow.

OK, what's the widest baffle you can tolerate? I mean it's got to be at least wide enough to get enough depth for the horn. Anyway, yeah, a stackable three box MTM seems like a plan.

GM

Ok Front baffle can be up to 36" max would prefer 32"-34" sides 32" max can be as high as 60"-64" just the bass bins with the horns on top of that.I had to install a split-level ductless AC unit today and was 95 degrees .I'll be taking it real easy tomorrow myself.Did you get that attachment I sent you.Is that cabinet design workable with the back corners cutoff, triangular,for corner placement?? Thanks Again.Regards ~ John

[bfish]

Not the easiest build, but I'm thinking modified corner Ultraflex cabs (roughly like these);



...stacked as MTMs roughly like these (insert U-flex boxes and 511 w/baffle);

[bfish]

Understood, when I saw that plot I could see it coming round the bend........... Frankly, I think the plot is another of those many marketing errors we found/joked about some years ago, but will take another look at it when I'm not so preoccupied.

GM

Lacking a comparable, I'm inclined to agree, except for the fact that it's fairly well in line with what (little) I know of line array theory.