AMT3 definitely the best ESS did with the Heil. anyone who didn't think so probably had very different listening tastes. i was surprised at the time that the "Rock Monitor" was good for all types of music, not just rock. i couldn't afford one though but used to listen to it for extended periods at the audio stores from time to time. i agree somewhat that the Tower was not a great speaker but build quality was not much of an issue. I was disappointed after ESS had bowled me over with the Transatic and Translinears before that (ESS was definitely near the top of the state of the art in the early 70's). I always wondered why they didn't mount a Heil on top of the Translinear, though a salesman said the KEF drivers became cost prohibitive for ESS..
I agree on the AMT3. IMHO the stock unit sounds very good.
And like many high end speakers, they have a tendency to be picky with their driving equipment. This really makes a huge difference in the bass/mid-bass response when dealing with the stock woofers in particular. Personally I have found H/K amplification works very well.
With the exception of the front baffle (which is easily remedied by a simple brace) the cabinet is solid over 1 1/2 thick walls and basically resonate free. Very heavy.
But it's easy to hear and see, if your willing to throw some useless bias/opinions aside, and think beyond the box. It provides the basic building blocks for the ultimate Heil speaker.
Higher crossover points, maximizing the Heils best frequency range, a 3 way design that aids in the transition between the (larger) woofer and the Heil by using a transition driver and dual , smaller paper cone woofers/transition drivers that blend well tonally with the Heil and have better then average transient response.
The ESS AMT3 crossovers where actually pretty good, fairly large gauge air coil inductors-nice thick PC board, but used electrolytic capacitors like many speakers of the day.
Lower ESR modern caps (and even larger gauge low ESR 'super inductors') make a audible improvement, and help improve efficiency (all good things).
The tighter tolerance components do have a audible improvement in imaging (which is already excellent IMHO stock) in really stabilizing things.
Driver technology has improved over the years-but the Heil still presents a challenge in matching drivers in a number of ways, efficiency, distortion, flat frequency response, transient response, and just as important tonal character. It easily points out those drivers not up to the task.
IMHO there is a lot of misunderstanding, particularly of the Great Heil, and really how to use-minimizing it's weakness, and accentuating it's positives. This is a bit puzzling, because there is really a wealth of beneficial information available, especially @ AK. Like most manufacturers of the time, and current, some of the ESS AMT speakers were compromises, especially the 2-way designs-but many find them satisfactory. And in my experience, I can image some of it was merely misidentified equipment mismatch.
I used to love Stereo Review-but their "theme" if you will, that you should simply able to (more or less) plug in components that had compatible stats on paper, and get satisfactory performance, gave audio novices of the time misinformation, and probably added to a lot of wasted/needless purchases.
I have spent some time trying to come up with the right driver combination-but finally have it narrowed down to a few currently/readily available drivers.
Sure you can pick at the negatives of what ESS did-but what good does that really do? Or you can look at the positive things they did, for example with the AMT3, and move on.
