XO between an AMT / Planar and a Cone

[Zodiac]

How would one go about best designing a crossover between a AMT and a cone driver.

In my winter dipole project I am currently thinking about using a 6.5" cone driver on a minimal baffle matched to a Beyma AMT with a low XO point of around 1300Hz.

However I am wondering if I am going to have power response issues since although horizontal dispersion will approximately match up there is a difference in the vertical dispersion of a tall AMT compared to the cone.

What are people's thoughts? I have been considering if a MTM design could be used to restrict vertical dispersion all the way up from the XO between the woofer and the MTM array, thus providing a smoother handoff to the AMT.

[audioandmusic]

Hi,
I havn`t posted here before, but as I´m pretty interested in AMTs and open baffle, too, I´ll give it a try:
As far as I understand, you´ll always have lobing problems once the driver distance goes past about half of wavelength at the chosen crossover point. The resulting diffraction pattern depends on the chosen crossover type.
I´m thinking of building a three-way box design or a four way OB thing with a small AMT according to the principles of the Horbach-Keele-crossover (FIR based) - not built for ultimate dynamics, but for high resolution and perfect diffractional integration. If you don´t like digital crossovers you´ll have to make other compromises...
Greetz!

[mige0]

@Zodiac
Don't let those issues keep you from trying an AMT, provided you have the funds.

Yes, a "big" AMT will always have different vertical and horizontal dispersion, but, who cares (literally !) ? - those speakers sound great, no matter how.
The main disadvantage of AMT is their price.
Mating the TPL with a 6.5" should do pretty. There's been an analogue project in German DIY audio magazine with very good data shown - though its been a boxed speaker there.


@audioandmusic
Lobing problems from two chassis is not related to diffraction (as such), its a simple time of flight problem with subsequent issues in constructive and destructive interference,

Whatever you do - audio is all about compromises - meaning, give it a try and have a look how much it counts for YOU, instead of considering a looooot of theories for " The Ultimate Solution" and never get started.


Michael

[StigErik]

The TPL150 is a bit problematic in dipole operation, as my measurement below shows. Because of its size, the polar pattern is rather ugly as well. This is why I ditched the TPL and use a much smaller Mundorf AMT.

[audioandmusic]

@Michael Thanks for explaining, your right. Everybody is tolerant to other degradations of quality and there´s no better way of learning than personal experimentation. Fortunately or not, I´m rather quite busy actively making music...

[wolf_teeth]

Originally Posted by StigErik

and use a much smaller Mundorf AMT.

What do you think of the Mundorf? In comparison to a RAAL for instance. I'm thinking the Airborne AMT's look decent as well, especially for the price.

Later,
Wolf

[theAnonymous1]

A 2-way AMT/6.5" has been on my to-do list for some time now. I already have the drivers.

I have four 6.5" drivers and haven't decided on whether to do MTM's or bi-poles.

I've already played around with the drivers using an "on the fly" digital crossover. I would close my eyes and move the crossover point around until I liked the sound; which would be right around 1.8kHz. Anything lower than 1.8kHz made the AMTs sound "shouty".

[StigErik]

Originally Posted by wolf_teeth

What do you think of the Mundorf? In comparison to a RAAL for instance. I'm thinking the Airborne AMT's look decent as well, especially for the price.

Later,
Wolf

Mundorf make great AMT's, my favourite tweeters so far. Never tested the RAAL ribbon, and probably will not since they are not dipole.

[mige0]

Originally Posted by StigErik

Never tested the RAAL ribbon, and probably will not since they are not dipole.

Aleksander also found out that dipole sounds nice too - after all
But this dipole tweeter is not available yet AFAIK.

My hope is he will make loooots of funds with it as to proceed to AMT finally - its just such a small step for a man of his profession and expertise - but he might be "mind blocked" and may need some more some time....


Michael