RandyInCaintuck has some of the actual Heil AMT's that he has experimented with quite a bit - perhaps he will see this and chime in.

Yep ..... the Heil AMT is one amazing driver.

Back in the day (when the first ESS speakers hit the market), one of the local audio vendors carried the ESS speaker that used the "Great Heil" driver. I was among the dirt poor at the time. Those who could afford the ESS speakers bought them ..... the rest of us bought something else .....

There were certainly some issues with the ESS speakers across some of the frequency range, but the highs were extended and airy and beautiful.

There has been a lot of discussion about the "best" way to use the Heil AMT driver and there are valid observations made from a variety of sources having differing opinions.

For a fact, if the driver is driven near the low frequency limits of its range, it has to be protected ..... so using it to run "full range" requires a crossover of some sort. If done well, it can sound very good used this way.

The other camp (which I happen to be in) thinks the very best sound from the Heil AMT is obtained when it is used as an upper midrange / tweeter.

The very best I have ever heard the Heil AMT was in the flagship speaker of Parker Audio ..... the Excalibur (originally known as the Behemoth). It was a floor standing speaker that used a limited production 10" driver running full range with the Heil sitting on top of the cabinet and crossed over at a point that was kept a secret ..... but it was pretty high for sure and used nothing but a single Duelund capacitor on the AMT driver.

The speaker was 4 ohms and 95 DB efficient and it would make some crazy good music with a 2 watt Decware amplifier.
I have never heard a better speaker ..... period.

Sadly there were only a few pair ever produced, but anyone who got to hear a pair experienced a rare treat.

I built a pair of open baffles that used a Heil AMT in a WMTMW configuration ..... two Hawthorne Audio Augies (driven by their own plate amps), two Visaton B200s running full range and a Heil driver in the middle crossed over at around 13 K.



They sounded good, but I concluded that the Heil driver sounds best by far sitting on the top of a cabinet. Having it surrounded by wood on every side closed down the airiness that the driver is capable of ..... despite being open in the back.

If I ever build a pair of "ultimate" speakers for my personal use ..... they will more than likely include Heil drivers in some configuration .....

Happy listening,
Randy

Quote:


Well ..... I got to thinking about that and remembered that I already went there .....





They weren't much to look at, but sounded pretty good.
Since the Betsy driver is only down a few DB at 20K, I crossed over to the Heil driver with a single cap at around 15K.

From memory, the Heil drivers added a bit of "sparkle" and air at the top end ..... but since I am quite happy with the high frequency response from the Betsy drivers now, I guess it wasn't something I couldn't live without.

Truthfully, adding a pair of high frequency drivers that cost six times what the Betsy drivers cost probably seems a bit peculiar to a lot of folks ..... and mounting them on top of an open baffle speaker was certainly a hillbilly rigged affair .....

I hate to think about trying to work out something that would be pleasing enough to the eyes to offer to a customer ..... and shipping such a beast would be a great deal of fun .....

Even so ..... the Great Heil is a fantastic driver and well worth some experimentation for anyone with DIY skills.

Happy listening,
Randy

I was looking through some old web photos a couple of nights ago and came across something that might be of interest to readers of this thread .....

Several years ago, my audio system was quite a bit different than it is now.
The amplifiers and front end equipment are the same (or similar), but the speakers not so much .....

Here is a photo of my "old" listening room with a pair of the Parker Audio Behemoths (later to become the Excaliburs) and a pair of Decware designed SO Imperial bass horns.
The Behemoths incorporated the Great Heil AMT driver and were wonderful sounding speakers.



Larger photo here.

The two small speakers sitting on top of the Imperials were not hooked up.

It was a VERY impressive sounding system and several of the forum readers of that time period had the pleasure of hearing it when they visited my home. The SO Imperials were wired in parallel with the Behemoths and everything was powered by a Decware SE84 Select amplifier. It was hard to believe that two watts per channel could produce the SPLs that the system was capable of.

Unexpectedly, I came down with stage four cancer and the doctors were pretty sure I would be taking the dirt nap in the near future ..... so I sold off most of my audio gear to keep my wife from having to deal with it when I was gone.

Happily, it appears that Ohio doctors don't know much about boys from Caintuck and I am still here nine years later and enjoying music  .....

My current system obviously sounds a lot different from the one in the photos ..... two different ways to skin a cat. Both good .....

Happy listening,
Randy

Hi Rob,

Yep ..... I have been a regular attendee at the Hornshoppe Fest in South Carolina and have known Ed Schilling for many years .....

I also have the dubious distinction of having hosted an audio fest at my home several years ago and to my knowledge it was the only time Steve Deckert and Ed Schilling were under the same roof at one time.

I am a shameless "name dropper" .....

Best wishes,
Randy