Since this is about the AMT I reckon I might as well help you guys learn a few things. I will have to reference my favorite speaker as example but the concept can be used in many other designs.
First, I need to say I am “buddies” with Rico (“Ricky”) CEO of ESS and I have OEM status. I do not sell The Great Heil but can use and sell them in my designs ( I'm not restricted to just my favorite speaker) .
You do not have to take my word for anything but if you do the research you will see I am correct in my statements, if not, by all means call me on it. Before you do you'd better have read the patents and done the research on 1st order series xover and how they are unlike any other slope or type.
The thing is, in order to take advantage of how they can benefit a DIY guy you must know they require drivers that can cover several octaves.....as like a full range speaker/driver. A pretty much full range driver and a Heil can be a perfect match. The 1st order series xover will insure both divers will have the exact same xover point. Change the impedance on either driver and the xover point shifts for both drivers. Same with the values, if not “perfect” the xover will just shift a little for BOTH drivers.
This is why I use The Great Heil mated to my favorite speaker. The 126 can be xovered anywhere and the GH can be safely xovered at above 1.5K or so with a 6db. Below that 12db for safety and at 800Hz you better have 18db. The sensitivity of both drivers is within a couple db of each other. This combo is ideal for the series xover and benefits greatly from it as would any design that could properly use it, IMO. I can move the xover from 1.5 to 10K if I want. The point I use is “classified”. ESS designs and almost all DIY do not take this approach and can not benefit from the series xover. I do things differently. The total moving mass of my system is 5 grams and is 97db efficient in corners as they should be.
The addition turns my favorite speaker into a true 2-way. It is not an “add on tweeter”. It is a SOTA 2-way that properly placed in corners has response to ~50Hz. Which was the design goal. A sub or 4 is always best for the bottom octaves IMO but most of my guys do not use them.....they put them in proper corners, as designed. I have a sub.
So do the research on the series xover and see if it will work for you....it will insure perfect slope for both drivers regardless of their impedance's or not exact values for the inductor or cap, even if not on perfect target so far as freq.. Xovers are seldom perfect but 1st order series insures the point is the same for both drivers regardless. It's special if you can use it. DO NOT USE WITH DIGITAL AMPS!
Now, this may upset some folks but here it goes.......In order to be able to discuss the Great Heil with any understanding of it YOU MUST READ THE PATENTS!!!!!!!!!
If you don't you may say something easily disproved by them, so here goes and I'm not going to do the work for you, I'm just gonna lay out the facts.
No other “AMT” can possibly sound like them. When the patents expired all kinds sprang up. They are easily outperformed by the highest quality soft domes such as the DynAudio D-28 and it's various types. I sure wish they still sold them DIY. Yea, being me I can snag a pair but only for personal use. No point in that!
So here is the deal.....ALL, I repeat ALL “AMT's “ operate with a pleated diaphragm. And that is where the similarity to the GH ends. The dispersion of them ALL is no better than any other driver and maybe not as good as the best soft domes with a proper xover.
So here is the thing few are aware of....the GH have increasing dispersion with rising frequency. They beam less as freq. goes up. No other driver does this I am aware of. Check out the patents....you'll understand why they look like they do and no others are it's equal.
So, there you go, don't fart around with imitators, design a speaker that can use the GH. I've given more than enough hints. This post is mainly for the DIY but everyone interested in the AMT type drivers should read the Heil patents. Knowledge is power!
Hope this helps.
ps...I kind of got dragged back to AC, I'll leave you guys alone now. Thanks for cleaning up a mess.