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wired them "correctly" just now and did some listening. so much more focused than before.

Overall, the sound of the Heil is a bit... not sure how to describe it, maybe "grainy"? Not clean and...

2 feet.

110dB is crazy high. I am measuring at ~80-90dB. My family won't talk to me anymore and that's not just because I am wearing earplugs!

Impulse response comparison. The wires are flipped, confirmed85737!

Are you saying, since it is a symmetrical dipole, just point it backwards? :applaud:

Phase measurements, comparing the 2 units.

Here is the weird one. And I have double checked the wiring and double checked the measurement. If I wire the positive to blue, and negative to brown,...

Comparison of my 2 Heil AMT's. They are produced on the same day, consecutive serial numbers.

Note the scale. They are within 2dB of each other without large deviation in overall shape.

The...

Distortion. Looks quite good from 900Hz and probably can go down to 800Hz.
85734

Dispersion measurement. Not bad. By the time it got to 50 degrees, the microphone can no longer "see" the diaphragm directly.

85733

I have a pair of current production Heil. Let me make some comparative measurement this weekend.

I scan them without protection cap from 200Hz upwards with a 4W amp. No problem. :applaud:

I did some sim before and had planned to make a 1/2 cu ft sealed box for the 2123. I think seal box will give a faster response. Never gotten around to building it though. Too much stuff to play with...

to follow up. here is a measurement after clearing some junk around the Heil and also raised it 1 inch (dark green), and 2 inch (purple) from the top of the cabinet, measure from ~1m.

Yellow is...

Nice! Did you build that enclosure?

I have a practically brand new 2123H that have been sitting around. Time to bring out the saw table...

I am still not sure if a traditional driver will be...

Last night I cleaned up the setup. Removed all the clutter, and then putting the Heil at the front edge of the 15" cabinet, overhanging just slightly, and then raised up by 1" to give the V shaped...

The other issue is that the Heli only go down to ~1kHz. What to put in the very important ~200-1kHz range that will match its speed?

This Heil AMT has been quite enjoyable.

The character is different than a compression driver horn. On the plus side, it is quite dynamic and fast (though not as fast as compression horn). The...

True. But a bit academic as I am not wearing them as headphones. :)

Let me try that. I will also try to play around with the placement. Right now the Heil is sitting on the (not connected) JBL 2397. I will try to remove that heavy thing and measure again. That should...

Yes I did and it made little difference. Some wiggles here and there but overall shape of the response remains mostly the same.

Rob you must have an anechoic chamber at home coz I can never get measurement as smooth as your at my room.

Here are mine. They are active DSPed together so I was able to do tweak it some more...

I am driving them directly from the amp. I haven't found any impedance plots online.

I googled for Heil AMT FR plots and some of them do exhibit roll off but some don't. very strange.

I will...

I will definitely do that.

That was early last week, but I remember in my measurement the Heil drops off pretty quickly after 10kHz. Your measurements looks much better.

Also I was driving them active crossover and for the...

I was playing with the ESS Heil I got last year from the same sale. Put them with the 2216ND-1 which surprising sound not bad!

Will post pics and measurements this weekend.