D'appolito - MTM and MMT's

[Bent]

Two questions
are all speakers in a MTM config considered D'appoplito types, and if not, would the MTM design offer the same vertical dipersion characteristics as a D'Apppolito?

I understand the concept of how a MT can/will result in "lobing", and why a D'appolito type doesn't.

[ThomasW]

By definition D'Appolito = MTM

All speakers have a lobing patterns (dispersion characteristics). Different driver configurations have different lobing patterns.

[cjd]

I believe the original concept called for 3rd order butterworth crossover slopes... Not sure if this is part of what is required for it to truly be D'Appolito.

C

[Bent]

IIRC, a higher order d'appolito had different lobing than a lower order...

I realize I used the term lobing in the wrong context now, d'appolitos lobing is always constant, and the lobes don't change with frequency - but a MT's lobing would chenge with frequency.

(or something like that).

[ThomasW]

Let the battle begin.....

http://www.birotechnology.com/articles/VSTWLA.html

[BobEllis]

The D'Appolito original concept was third order Butterworth and exhibited a fairly uniform vertical distribution in the crossover region when the drivers were within a wavelength. I have heard that Joe himself uses fourth order filters these days, which show a relatively narrow vertical dispersion pattern in the crossover region.

There will be some lobing outside the crossover region as designed by the driver geometry. Every system has off axis response that varies with frequency, even "full range" single driver speakers. The advantage of the D'Appolito arrangement is the pattern does not tilt with frequency as an MT does.

Not that I have the credentials of the author of the article Thomas linked to.

[Bent]

that's sum gud readin'

[ThomasW]

that's sum gud readin'

Yep and there's a test in 2 hours...... :B