There have been AMTs...like the Hawthorne Audio "Rainier" (no longer made--to my knowledge). This dipole loudspeaker crossed from its horn-loaded AMT at nominally 350-450 Hz.
Several years ago, I tried to make contact with the gentleman that made the horn-loaded AMTs for that loudspeaker, to no avail (apparently the gentleman that made them either retired or passed away).
My own experience with ESS AMT-1 drivers is that they easily cross at 610 Hz, but they need either wing extensions and/or to be stacked two or three tall to get the kind of polar support they need to work well. Currently I use two-high stacks of ESS AMT-1s (keep reading on page 3) on top of Belle bass bins (bi-amped and dialed in) as my surrounds in a 5.2 setup. They sound much better than any horn-loaded tweeter/midrange horns that I've tried on them before.
Chris
Several years ago, I tried to make contact with the gentleman that made the horn-loaded AMTs for that loudspeaker, to no avail (apparently the gentleman that made them either retired or passed away).
My own experience with ESS AMT-1 drivers is that they easily cross at 610 Hz, but they need either wing extensions and/or to be stacked two or three tall to get the kind of polar support they need to work well. Currently I use two-high stacks of ESS AMT-1s (keep reading on page 3) on top of Belle bass bins (bi-amped and dialed in) as my surrounds in a 5.2 setup. They sound much better than any horn-loaded tweeter/midrange horns that I've tried on them before.
Chris
Dayton Audio AMTPRO-4 is very close, suggested lower point is 800 Hz, if used on moderate SPL level, with steep filter, then distortion is probably acceptable.
Also B&G Neo8 and his clones can handle 500 Hz.
Also B&G Neo8 and his clones can handle 500 Hz.
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GRS has a 10" and 8" Planers.
Impedance as usual, is pretty flat.
What would be considered resonance
is around 250 to 330 Hz
GRS PT5010-8 ohm 10"
GRS PT6825-8 ohm 8"
GRS PT6816-8ohm 8"
The bigger PT5010 could go down to 500 Hz
I played around with it in sim with 4th order crossover.
Response looks little roller coaster and has rising top end.
I got it flat in sim with passive crossover.
About 91 dB
Looks about like this
And quick sim with live sound 12" woofer got it to this
Ironically about 500 Hz crossover. likely add another
ribbon at 3k or 4k. Shown on bandpass I never added
a tweet, was just playing around with it.
Impedance as usual, is pretty flat.
What would be considered resonance
is around 250 to 330 Hz
GRS PT5010-8 ohm 10"
GRS PT6825-8 ohm 8"
GRS PT6816-8ohm 8"
The bigger PT5010 could go down to 500 Hz
I played around with it in sim with 4th order crossover.
Response looks little roller coaster and has rising top end.
I got it flat in sim with passive crossover.
About 91 dB
Looks about like this
And quick sim with live sound 12" woofer got it to this
Ironically about 500 Hz crossover. likely add another
ribbon at 3k or 4k. Shown on bandpass I never added
a tweet, was just playing around with it.
Yes exactly.
Same thing I was thinking using affordable more common Dayton or GRS planars
And using very steep filters.
I was pretty surprised by how low the GRS PT-6816 goes:
https://www.parts-express.com/pedocs/specs/272-128--grs-pt6816-8-spec-sheet.pdf
The aforementioned planar runs out of steam at 15khz. I haven't tried it yet, but I'll bet three of it's smaller siblings can likely give it a run for the money, since the additional surface area raises low frequency output and power handling:
https://www.parts-express.com/pedocs/specs/272-122--grs-pt2522-4-spec-sheet.pdf
Plus, they're on sale.
I tried one of the Airborne AMTs but wasn't thrilled with the low frequency output. The back chamber is basically non-existent, which limits low frequency output.
With all of these, I wouldn't bother using them without a waveguide.
https://www.parts-express.com/pedocs/specs/272-128--grs-pt6816-8-spec-sheet.pdf
The aforementioned planar runs out of steam at 15khz. I haven't tried it yet, but I'll bet three of it's smaller siblings can likely give it a run for the money, since the additional surface area raises low frequency output and power handling:
https://www.parts-express.com/pedocs/specs/272-122--grs-pt2522-4-spec-sheet.pdf
Plus, they're on sale.
I tried one of the Airborne AMTs but wasn't thrilled with the low frequency output. The back chamber is basically non-existent, which limits low frequency output.
With all of these, I wouldn't bother using them without a waveguide.
With GRS I've seen some pretty ****-poor QC, which isn't surprising since they scrape the barrel on pricing. I'd be skeptical of using anything from them without buying twice as many as you need and rejecting half the samples. That's not inherently problematic, rejection rates are high for many precision fabrication industries, but I'd rather have something I know will be at least on-spec to start from, as for matching, Someone could get lucky with their first pair, or need 20 to get within +/- 1 dB matching.