ESS AMT Heil Driver ID

[witoman]

Hi, can anyone ID the ESS AMT Heil driver from these links?

ESS AMT Heil driver, front

ESS AMT Heil driver, rear

The driver and mounting in the photos measure 7" x 7" x 3.5" deep.

Thanks, Bill

[porschedpm]

I don't believe JBL ever used the Heil Air Motion Transformer for any of their speakers. You should probably send an email to ESS to see if they can identify it. For what it's worth, and I'm no expert, but this definitely doesn't look like their top of the line AMT. And it looks bigger than the entry level AMTs I've seen.

[witoman]

You're right, I don't believe that JBL ever used the ESS Heil driver in their speakers. That's why I cautiously posted my query in the Off Topic forum. Sadly, I have now emailed ESS twice with no response. I posted here simply because the Lansing forums have the most knowledgeable folks about vintage speakers. Thanks.

[tomt]

have you heard those tweeters?

[Steve Schell]

I haven't seen this model before, but they look as though they could have been manufactured by ESS. They made many versions of Dr. Heil's air motion transformer driver over the years. The driver in the AMT-1 series was a dipole, i.e. radiated equally to the front and rear. Other models were flush mounted to box speakers, and their rear wave was absorbed with damping material. I can't quite tell from the pictures how these were supposed to be used, but look like they could be set up for dipole operation.

The AMT-1 drivers in particular are excellent performers, fairly efficient with really good attack and dynamics. These look like they might use the same diaphragm, and may sound just as good.

[witoman]

have you heard those tweeters?

Yes, I have them running off of an external electronic crossover at 7KHz. I have pseudo JBL L200B's running below 7KHz. These Heil's sound very good, but I've got some 2405's on order that I will compare them to. The Heil's definately improve the "airiness" of the L200B running by itself.