Are Dayton AMTs Any Good?

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#2
The distortion is actually a strong point:

AMT tweeters - explored by Critofur - Techtalk Speaker Building, Audio, Video Discussion Forum

I have a pair of Pro4.

PROS: Robust, light, can cross low, decent efficiency, optionally a dipole, you can remove the frame for tighter spacing or to mount it coaxially in front of a midwoofer or horn.

CONS: Doesn't go to 20kHz. FR not as flat as a decent dome tweeter. The FR is possibly hard to measure / varies more with distance than a dome tweeter would (the further you are, the more like a point they behave?) With a longer mic distance, I measure a bit more HF extension than Critofur did, and I also recorded more of a hump around 10kHz.

PRO or CON: narrow sweet spot in one axis

Note that most of the negatives aren't a problem if you're using a mic + miniDSP or equivalent.
 
#3
hollowboy said:
The distortion is actually a strong point:

AMT tweeters - explored by Critofur - Techtalk Speaker Building, Audio, Video Discussion Forum

I have a pair of Pro4.

PROS: Robust, light, can cross low, decent efficiency, optionally a dipole, you can remove the frame for tighter spacing or to mount it coaxially in front of a midwoofer or horn.

CONS: Doesn't go to 20kHz. FR not as flat as a decent dome tweeter. The FR is possibly hard to measure / varies more with distance than a dome tweeter would (the further you are, the more like a point they behave?) With a longer mic distance, I measure a bit more HF extension than Critofur did, and I also recorded more of a hump around 10kHz.

PRO or CON: narrow sweet spot in one axis

Note that most of the negatives aren't a problem if you're using a mic + miniDSP or equivalent.
Click to expand...

Interesting.

I like loading ribbons on waveguides, but I've generally avoided it for a few years now because I always blow up the ribbons.

I know that a BG NEO 3 will work, but I've been reluctant to use my pair because they were unobtanium. (I know they're back again.)

So the AMT might be a viable option.

I've been wanting to build a Synergy Horn for my home, and I was leaning towards the RS28.
 
#4
Patrick Bateman said:
Interesting.

I've been wanting to build a Synergy Horn for my home, and I was leaning towards the RS28.
Click to expand...

RS28?

You must have a big living room, and some interesting contacts.

Where are the BG NEO 3 available (link)?
 

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#6
speakerdoctor said:
Dayton AMT's have very low power handling specs. Thus, the designer must be careful to not cross to low or be forced to use high order transfer functions to minimize distortion.
Take a look at the difference between Dayton AMT specs and Mundorf AMT specs.
Click to expand...

The AMT29CM1.1-R looks like the closest equivalent to the pro4. It has:


  • Higher efficiency. That's genuinely good, IMO. I'd rather have +6dB from a higher efficiency than from quadrupling the power used.


  • More power handling, so you can turn them up to eleven, if you have the power available.

...so about 10dB more capablity


  • Better output at 20kHz (within the sweet spot, a 5-degree window) which is possibly important for the hordes of us with the hearing for it (female or under 30), who usually listen in one chair, and who will happily spend US$1280 on a pair of tweeters 🙂

So for some applications, the Mundorf looks a lot better, possibly enough to justify paying five times as much. However:


  • Less LF output. The rolloff is about an octave higher.
...so for home use and crossing lower than 2kHz, it looks like the Dayton would be the one to use, particularly if money is a factor.

A final consideration:

For equivalent cost, you could either stack up an array of 5 of the Dayton units or use a single Mundorf unit.

The array would have great power handling, better low end, and a MUCH bigger vertical listening window - the latter being arguably the weakest point of any of unit of this type, when used singly. And it would look great!
 
#10
I have the Dayton AMTPOD4 (designed for stick on treble in a car):
AMTPOD-4 Motion Transformer Automotive Tweeter Specification Sheet

It sounds nice, but nothin' compared to my big Heil ESS AMT - truly a world class tweeter, one of the finest sounding tweeters ever made.

RS28 is a wonderful dome tweeter (is yours the A or F model?), but you should really try a small full range like SB65WBAC25 for the mid-tweet on a synergy. Skip the mid injection ports and just do bass ports letting the cone mid/tweet in a horn handle 500Hz on up.

http://www.diyaudio.com/forums/multi-way/285030-bookshelf-multi-way-point-source-horn.html

AMT's sound wonderful in a horn btw.

I am making a new transient perfect 3-way with the RS28F:
http://www.diyaudio.com/forums/multi-way/297171-rs28f-rs180p-b80-hole-filler-3-way.html
 
#11
I own a pair of AMTPro-4 and compared it to the Beyma TPL-150. The Dayton was measured without faceplate and with a damped back chamber. The driver was equalized coarsely for the non-linear distortion measurement. The Beyma was measured without the horn.

As you can see distortion is very low and on the same level as the Beyma. Vertical directivity is as expected for such a long driver. This is no special behaviour of this model. Every driver with this dimensions produces the same narrow dispersion.

Decay is very good on both drivers.

Amplitude response is a bit weird, but with an DSP controlled crossover this is no show-stopper. In fact AMTPro-4's performance is very good for that price. Please keep in mind that the TPL-150 costs about three times as much!
 
#12
xrk971 said:
I have the Dayton AMTPOD4 (designed for stick on treble in a car):
AMTPOD-4 Motion Transformer Automotive Tweeter Specification Sheet

It sounds nice, but nothin' compared to my big Heil ESS AMT - truly a world class tweeter, one of the finest sounding tweeters ever made.

RS28 is a wonderful dome tweeter (is yours the A or F model?), but you should really try a small full range like SB65WBAC25 for the mid-tweet on a synergy. Skip the mid injection ports and just do bass ports letting the cone mid/tweet in a horn handle 500Hz on up.

http://www.diyaudio.com/forums/multi-way/285030-bookshelf-multi-way-point-source-horn.html

AMT's sound wonderful in a horn btw.

I am making a new transient perfect 3-way with the RS28F:
http://www.diyaudio.com/forums/multi-way/297171-rs28f-rs180p-b80-hole-filler-3-way.html
Click to expand...

qfQtTR7.jpg

Here's the frequency response and distortion of an RS28 on a waveguide I cobbled together out of plywood. There's 1uf cap in series to keep the tweeter from blowing up.

I haven't finished the project yet, but I think I like the sound better than the SB Acoustics on a WG. Due to the high excursion of the RS28, you can get away with an acoustic high pass in the range of 1000-1500hz, and that works pretty well on a Synergy Horn. Although the SB65 can go lower, it's efficiency is much lower. When I tried it, it lacked in dynamics IMHO, and when played at moderate levels it sounded like I was pushing the driver too hard. It wasn't distorting outright, it just didn't have the dynamics I've come to love.

I've tinkered with a ton of different tweeters on Synergy Horns, and at the moment I think that the 3/4" dome from SB and the RS28 are my favs. To my ears, most compression drivers sound a little grungey in the top two octaves. There are exceptions to the rule, like the BMS 4540nd, but it can't be crossed over low enough to meet up with most midranges on a Synergy Horn. I've tried ribbons on Synergy Horns, and they sounded great, and then they exploded. (Literally, into shards of aluminum.)

So... That's what got me wondering about the AMTs.
 
#14
ernperkins said:
Did you really use a 1 uF cap for protection? Try a 25 uF cap instead, I think you'll see a large difference in frequency response.
Click to expand...

A loudspeaker on a waveguide has a rising response in the lower octaves.
This is because the energy of the loudspeaker is constrained into a smaller angle.

By setting an electrical high pass at 20,000hz, you get flattish response due to the combination of the electrical filter and the rising response of the waveguide.
 
#15
Patrick Bateman said:
I've tried ribbons on Synergy Horns, and they sounded great, and then they exploded. (Literally, into shards of aluminum.)
Click to expand...

O.M.G, it's obvious bad use, not covered by legal guarantee...😀

https://www.youtube.com/watch?v=A3sHFBCXR3I

Btw, horn loading should help better power handling, in my book, but yours is so weird that i suspect you might easily get the opposite effect...
 
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#16
I have the AMT pro 4 and the mini. Distortion measurements on the pro 4 are better than most (any?) cone, dome drivers with a similar bandwidth.

They dont handle as much power as a Beyma TPL150 but those were designed for PA use and cost 6 x as much

Good unit to unit consistency between the pro 4 but not so with the mini - at least with my 2 samples

If you like the "AMT sound" they are great value and compete with the expensive units for hifi use
 
#19
From my experience you can use pretty much anything for ambience tweeters. Room and placement are the overiding factors. Better option is to use an appropriate tweeter on the front so you dont need to use an ambience tweeter. Or go dipole
 
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