HEIL amt & audax midrange (open baffle question)

[bytelight]

Hi there

as noticed here are some guys playing around with heil air motion transformer and/or Audax midrange drivers.

My question is,

1. is there someone aroung using an audax pr170mo as midrange in open baffle

2. what is the best crossoverpoint for the configuration of Audax and ESS AMT "1" (the big one)

3. which combinations have been made with the big amt in thiz forum.
e.g.
AMT/Peerless 12"
AMT/PHL 1120
......

please comment !
kai

[Hannibal Selector]

What's up, Southern Germany? I know zero about OB, but have read and
participated in a few threads that you might find interesting as far as midrange
choices and preferred crossover freqs. I'll send you some links, but it's going
to be a few hours before I have time to do so. Talk to ya later.

[badman]

2khz for the crossover, unless you horn load the heil, in which case it'll do 1k nicely. pr17OMO has been extensively used on OB, you'll want to cross in the several hundred hz to the woofer, and higher if you need more power handling. There are long threads on the amt so take advantage of the search feature.

[Hannibal Selector]

"There are long threads on the amt so take advantage of the search feature."
*
Badman's advice is good, there's a lot here & at audiokarma as well.
Below are some quotes from one thread (link below). The first two are from
post 70 there. Not everything in the thread will apply to your project, but I thought
these 3 points at least would interest you:
__________________________________________________ ___________
"2.) Distortion climbs dramatically as frequency goes down below 1500 Hz. I can't believe ESS originally crossed these over at 700 Hz. That probably wouldn't fly in today's world - the stereo mags would rip them to shreds."

"3.) The other interesting thing that happens below1500 Hz is that they start
behaving like a dipole. In other words, they fall off at 6db / octave as the rear wave is cancelling the front wave."

My Great Great Heil DIY Speakers - AudioKarma.org Home Audio Stereo Discussion Forums

From another commenter on the same thread:

"I'm not going to begin to try and convince someone I'm a speaker expert. Far from it. But, there happens to be one speaker I know a little bit about, and that is the 'big' or 'Great' Heil AMT. Been using one for over 20 years. Yes, they can be crossed over as low as 1000Hz, but I do not particularly care for the nasal-sounding midrage you get from them at the lower end of its response range. In a two-way setup, the best route is to use a 6 1/2" or 8" woofer (two per cab, if you like) that has decent response out to 3K or so, and cross over to the Heil at 2.2K to 2.6K."
__________________________________________________ ____________

Here's something I repost in a number of places, a gallery you might
really enjoy:

"BTW, for any AMT/ESS junkies here who haven't run into this
awesome gallery of ESS ads, here's a link I first saw posted by
Cactus Bob @ AK:

* Michael Otto's Archiv * - ESS_Lautsprecher

Clicking a thumbnail gives you a not-so-big shot of the ad, but click
again and you get full-size."
__________________________________________________ __

I'm pressed for time again, but maybe tomorrow I can dig deeper into my
bookmarks and come up with some of my favorite AMT links.
Hope this helps.