Do you like AMT tweeters?

[JohnnyAudio]

What do you mean by edge?

I wish I could give a better technical answer, the ESS seem to have a non flat response.

 

[ThatSoundsGood]

Dear SoundsGood,

Are the Mundorf AMT's much better/ different than the ESS AMT's? I have 6 ESS and like them but there is an edge to them that I wish was better.

I haven't use the ESS stuff so I can't comment on the difference. I know that the Mundorf's measure really well and mine is my favorite tweeter I have ever used.

 

[ThatSoundsGood]

I wish I could give a better technical answer, the ESS seem to have a non flat response.

A non-flat response is easy to measure. My Mundorfs are +/- 1db from 2Khz to 14Khz in my design which is a very simple 2nd order crossover. Off-axis is the real key because the vertical dispersion is limited and not needed.

 

[ThatSoundsGood]

As is so often the case, there are far too many generalizations here.
There are good and bad dome tweeters, and there are bad and excellent AMT tweeters.
In both cases, the problem lies not with the principle, but with the technical implementation.
An AMT has great potential for technical excellence, but in some implementations it fails due to a lack of experience and technical implementation.
The diaphragm, which is the heart of the AMT, must be folded and installed very carefully.
Unfortunately, this results in very large variations in quality at some companies.
I have not yet encountered any outliers at Mundorf, but I have at other companies.

Agree 100%

 

[Ktacos]

distortion is only a problem with AMTs which are too small or the crossover freq is overly low. If sized and driven properly, they can be exceptionally clean.

Seems like most still have higher distortion than the little guy in the micca mb42x, regardless of xover freq.

 

[dfuller]

Seems like most still have higher distortion than the little guy in the micca mb42x, regardless of xover freq.

You'd think the way higher radiating area would help that, but no.

 

[Sjkrabbe]

to my ears AMTs are so easy to listen to and easy to work with mixing all day without listening fatique. I haven´t ever cross checked with other treble transducers, but I never seem to miss the details at all with AMTs - mostly heard in them ADAM speakers and lately in Radiant Acoustics Clarity speakers

 

[ThatSoundsGood]

The distortion on Mundorf AMT's measures a bit higher than some domes, but low enough to not really be much of a problem if crossed over correctly and used in a situation where the dispersion characteristics are helpful. If you're looking for the lowest distortion tweeter then a beryllium or TPCD would be the way to go. And I can only speak for the Mundorf AMT that I used. It's really flat with an easy crossover; better than any dome I've used including stuff in waveguides. So I like the trade of near perfect flat response with a bit more distortion vs lower distortion and a bit more frequency variation. Maybe they're not worth the money to some people and that's totally understandable, but they are definitely my favorite tweeter that I have used and they are in my living room speakers where we mostly watch movies. I use beryllium tweeter domes for mixing because they are lower distortion. So again, it's design dependent and ultimately it's what you're going for and how it will work in the room.

 

[Arindal]

If you're looking for the lowest distortion tweeter then a beryllium or TPCD would be the way to go.

Had a similar impression that many beryllium tweeters tend to show exceptional behavior regarding transparency and clarity. As most of these are either very flat dome tweeters or inverted domes, they also show a pretty broad dispersion pattern at lower frequencies, which makes them sound very different to AMTs, particularly the taller Mundorf units. So I don't really see the point in a comparison as the two are made for different applications IMHO.

For studio purpose, this broad radiation is fine, for home application, it seems to be pretty difficult to match it with a midrange and narrow down directivity, have never met a speaker which successfully combined Beryllium dome and waveguide/horn. Closest approximation being maybe TAD R1 and its compact derivative, but their dome is bigger and the midrange of the coaxial pretty unique.

Seems like most still have higher distortion than the little guy in the micca mb42x, regardless of xover freq.

Higher distortion on paper or audible distortion?

 

[ThatSoundsGood]

Had a similar impression that many beryllium tweeters tend to show exceptional behavior regarding transparency and clarity. As most of these are either very flat dome tweeters or inverted domes, they also show a pretty broad dispersion pattern at lower frequencies, which makes them sound very different to AMTs, particularly the taller Mundorf units. So I don't really see the point in a comparison as the two are made for different applications IMHO.

Totally agree. I mix on speakers with beryllium tweeters and my TV/Movie system in the living room has a tall Mundorf tweeter because I don't need any vertical dispersion there. I can't hear the distortion in the Mundorf compared to the beryllium tweeter though.

For studio purpose, this broad radiation is fine, for home application, it seems to be pretty difficult to match it with a midrange and narrow down directivity, have never met a speaker which successfully combined Beryllium dome and waveguide/horn. Closest approximation being maybe TAD R1 and its compact derivative, but their dome is bigger and the midrange of the coaxial pretty unique.

Lots of DIY stuff with this tweeter can achieve it pretty well:

Satori TW29BNWG-4 Beryllium Dome Tweeter with Waveguide

Satori TW29BNWG-4 Beryllium Dome Tweeter with Waveguide

www.madisoundspeakerstore.com

Higher distortion on paper or audible distortion?

Good question, because I can't hear the distortion in either.

 

[a4eaudio]

...Higher distortion on paper or audible distortion?

Good question.
I have been working with some AMTs lately and a lot of the designers I know prefer a ribbon, AMT or planar tweeter over domes. I was hoping this thread would show some good objective reasons why. There was a recent thread on Ascend Acoustics where the owner was explaining objective reasons why 90% (?) of his customers choose the RAAL over Seas DXT in blind listening. After seeing the post about higher distortion I was curious about that too.

But it turns out there is hardly anything objective in the 170 posts of this thread. (To be fair, the thread is titled "Do you like AMT tweeters" which is kind of like asking do you like chocolate bars.) Post #34 shows very low distortion for the Beyma TPL-150H. Post #103 links to an Audioxpress article that shows low distortion for the Beyma TPL 200. Post #118 links to several Adam Studio Monitors that seem a little hit-or-miss. I would also point out that hificompass.com tests several AMTs and almost all have quite low distortion. I don't see anything objective in this thread to suggest that AMTs are higher distortion and especially not AUDIBLY higher distortion. But I also don't think lower distortion is the reason so many people prefer them. What else is it, less energy storage, less compression?? I would think some people on ASR would have some constructive objective hypotheses on why so many people prefer AMTs (or ribbons).

 

[Salt]

Good question.
I have been working with some AMTs lately and a lot of the designers I know prefer a ribbon, AMT or planar tweeter over domes. I was hoping this thread would show some good objective reasons why. There was a recent thread on Ascend Acoustics where the owner was explaining objective reasons why 90% (?) of his customers choose the RAAL over Seas DXT in blind listening. After seeing the post about higher distortion I was curious about that too.

But it turns out there is hardly anything objective in the 170 posts of this thread. (To be fair, the thread is titled "Do you like AMT tweeters" which is kind of like asking do you like chocolate bars.) Post #34 shows very low distortion for the Beyma TPL-150H. Post #103 links to an Audioxpress article that shows low distortion for the Beyma TPL 200. Post #118 links to several Adam Studio Monitors that seem a little hit-or-miss. I would also point out that hificompass.com tests several AMTs and almost all have quite low distortion. I don't see anything objective in this thread to suggest that AMTs are higher distortion and especially not AUDIBLY higher distortion. But I also don't think lower distortion is the reason so many people prefer them. What else is it, less energy storage, less compression?? I would think some people on ASR would have some constructive objective hypotheses on why so many people prefer AMTs (or ribbons).

"Do you like AMT tweeters"
That's what this thread's about.
For more depth into technical interesting details and discussion don't hesitate to start an new thread.

 

[a4eaudio]

"Do you like AMT tweeters"
That's what this thread's about.
For more depth into technical interesting details and discussion don't hesitate to start an new thread.

...To be fair, the thread is titled "Do you like AMT tweeters

LOL, yeah I covered that in my post.
People are saying why they like and don't like them, discussing their directivity, their distortion, etc. They just aren't actually presenting supporting evidence. (Which is why I called attention to a few that actually did post real evidence about distortion - which tended to support low distortion, not high distortion.)
Pretty sure if I started a new thread about "why technically you like AMTs" it would get merged into this one by the mods.

 

[Salt]

LOL, yeah I covered that in my post.
People are saying why they like and don't like them, discussing their directivity, their distortion, etc. They just aren't actually presenting supporting evidence. (Which is why I called attention to a few that actually did post real evidence about distortion - which tended to support low distortion, not high distortion.)
Pretty sure if I started a new thread about "why technically you like AMTs" it would get merged into this one by the mods.

I would expect, that a new thread, that is about technical concerns about AMTs, would not be refused by Mods or anyone else.

 

[dfuller]

Since we want objective evidence:

AMTs typically sized for use as tweeters start to beam between 6-8k depending on its size. A typical 1" class hard dome doesn't tend to beam til up above 10khz somewhere, and a soft dome is somewhere between 8-10khz depending on when it starts behaving as a ring radiator. This is all flat baffle behavior; things change somewhat if they start to be waveguide loaded, but they still tend to beam fairly low compared to a typical dome just because their diaphragm dimensions tend to be a bit bigger to enable enough low end extension. We have spins on spinorama.org for probably a dozen AMT equipped speaker systems, and they almost all show exactly this behavior.

Now of course the problem here is that AMTs in typical tweeter sizes are usually not particularly happy crossing as low as a typical dome, which is a problem on 2-way speakers. Even on a flat baffle, a 1.7-2khz cross with 4th order filters is far from unheard of for a dome tweeter (I've seen flat baffles cross as low as 1.2khz, which I wouldn't personally advise, but I've seen it done). AMTs tend to be more in the range of 2.5-3khz which leads to more problems with directivity error, especially vertically.

So in essence we have a tweeter type that:
- beams lower than a dome, making toe-in tweakier
- also can't cross as low as a dome, making directivity harder to match

So what does this design solve for over a conventional dome? I just don't see it.

 

[ThatSoundsGood]

So what does this design solve for over a conventional dome? I just don't see it.

Decreased vertical directivity, which minimizes floor and ceiling reflections in designs that can be limited in vertical dispersion. This is particularly useful in 3 way floor standing speakers where the tweeter is head height when you're sitting on the couch or 3 way monitor designs when listening near field and you want to minimize desk reflections. This is a minor nuance, but true in specific situations.

 

[Audionaut]

have never met a speaker which successfully combined Beryllium dome and waveguide/horn

SATORI TW29BNWG-8 / Beryllium - Sbacoustics

Beryllium dome for non-resonant high frequency extension, dual balanced compression chambers for improved dynamics, solid aluminium waveguide.

sbacoustics.com

You don't like it?

 

[Arindal]

Now of course the problem here is that AMTs in typical tweeter sizes are usually not particularly happy crossing as low as a typical dome, which is a problem on 2-way speakers. Even on a flat baffle, a 1.7-2khz cross with 4th order filters is far from unheard of for a dome tweeter (I've seen flat baffles cross as low as 1.2khz, which I wouldn't personally advise, but I've seen it done). AMTs tend to be more in the range of 2.5-3khz which leads to more problems with directivity error, especially vertically.

Agreed to the higher x-over freq part, although we should remark that there are some taller AMTs which allow a pretty low crossover.

While some domes allow much lower crossover points, hence reducing the amount of vertical lobing, that is not necessarily an advantage in terms of directivity error. In contrary, I would argue that upper midrange and transitional (hence lobing maximum) band 1-2.5K offering pretty inconsistent directivity pattern, combined with a very low d.i. between 3-6K (that is what most domes w/o waveguide deliver) poses a big risk for imbalanced off-axis behavior. A waveguide can on paper solve this issue, at the cost of increasing the distance between midrange and tweeter, plus tending towards a continuously increasing directivity index.

An AMT, on the other hand, might give the speaker designer more of a headache when it comes to lobing around 3K and overly narrow dispersion above 7K, but offers a less steeply increasing directivity horiontally/vertically thanks to taller and slimmer diaphragm geometry. If combined with the right strategy of controlling lobing and midrange directivity (such as d´Apollito-style arrangements, midrange dipoles, line sources), the result can be superior in theory.

In the end it is a question of the overall speaker concept and the best compromise a speaker designer is willing to accept. For low-d.i. concepts such as nearfield or studio monitors, I would agree that an AMT does not offer any advantage over an excellent dome.

- beams lower than a dome, making toe-in tweakier

´Beams lower´ I would associate mainly with vertical beaming. Horizontally, a slim AMT can easily rival a 1" dome, if it is not broader than the latter.

Decreased vertical directivity, which minimizes floor and ceiling reflections in designs that can be limited in vertical dispersion. This is particularly useful in 3 way floor standing speakers where the tweeter is head height when you're sitting on the couch or 3 way monitor designs when listening near field and you want to minimize desk reflections.

Fully agree to the potential advantage of vertical beaming in theory, but I would render that useful only in cases it can be achieved over a wide frequency band. Limiting the treble beaming, like taller AMTs do, while keeping midrange directivity very low, does not sound like a promising concept to me.

You don't like it?

Don´t have enough of listening experience with that one to judge. It seems to be a more spherical dome, slightly bigger than 1", on paper showing some pretty steep increase in directivity above 5K, which I am not sure about how it will play out in terms of sound quality in a room. Which commercially available loudspeaker employing this tweeter+waveguide, would you recommend?

 

[Audionaut]

Hello Arindal,
I only know about this project from a friend who is a loudspeaker developer. I haven't heard them myself, but I trust his abilities and judgment.

Kaimana – edler 2 Wege Lautsprecher

Gelegenheiten muss man, einer alten Redewendung zufolge, beim Schopf packen. So ergab es sich, dass zwei Paare edler Lautsprecherchassis den Weg in meine Regale fanden. Dass die beiden Chassis wunderbar zueinander passen und die Grundlage für ein tolles Konzept bieten, war auf den ersten Blick...

www.donhighend.de

 

[Arindal]

Hello Arindal,
I only know about this project from a friend who is a loudspeaker developer. I haven't heard them myself, but I trust his abilities and judgment.

Kaimana – edler 2 Wege Lautsprecher

Gelegenheiten muss man, einer alten Redewendung zufolge, beim Schopf packen. So ergab es sich, dass zwei Paare edler Lautsprecherchassis den Weg in meine Regale fanden. Dass die beiden Chassis wunderbar zueinander passen und die Grundlage für ein tolles Konzept bieten, war auf den ersten Blick...

www.donhighend.de

Havent´t listened to such concept so I cannot comment on the sound.

Measurements indicate the directivity behavior I was describing and which I found to be taking away lots of the subjective transparency and qualities of such a Beryllium dome in similar concepts. While the overall directivity index between transitional band and its neighboring higher octave is remarkably even, this comes at the price of pronounced vertical lobing plus horizontal widening, and a steeply narrowing dispersion pattern above 4K. Don't really see the advantage here.