AMT tweeters - explored by Critofur

[critofur]

Here are photos of the AMT3-4 and AMTPro-4 tweeters with their faceplates off:

Flickr photo gallery



More to come...

VERY strong magnets of course, and on the AMT4-Pro they are exposed - I experienced the clamping onto my AMT3-4 accidently, had to pull pretty hard to separate them.

More measurements going here (can only attach up to five per post)

AMT3-4, unprotected, no faceplate, no baffle (on top of .5 cu ft speaker, 1 inch back from edge, mic centered on tweeter .5 meters away) FR + Distortions:

[critofur]

Measurement Post - updated again

AMTPro-4 (RED) and AMT3-4 (GREEN), unprotected, no faceplate, no baffle (on top of .5 cu ft speaker, 1 inch back from edge, mic centered on tweeter .5 meters away) FR:



AMTPro-4, unprotected, no faceplate, no baffle (on top of .5 cu ft speaker, 1 inch back from edge, mic centered on tweeter .5 meters away) FR + Distortions:



AMTPro-4(Red) and AMT3-4(Blue) + Distortions w/10uf in series:



AMTPro-4 FR + Distortions w/10uf in series:



----------- All measurements above this line without faceplates on the tweeters ------------

Measurement:


AMTPro-4 = Blue AMT3-4 = Green

Notes:

The faceplate on the Pro-4 is slightly thinner than the 3-4 and, so far, with all the units I've seen they come with a slight bend which I will try to carefully undo, though I'm sure if you order some and get them that way PE will gladly exchange them for you for un-bent ones.

The 3-4 faceplates do not seem to have the same problem (did not arrive bent).

As you can see in the photos, the Pro-4 comes with two pieces of felt stuck in the rear cavity. These are held in merely by friction (tight fit) and come out easily. Also as you can see in the photo the front comes covered with a thin nylon screen - this is not shown in Parts Express photos on their page for this tweeter.

[dlneubec]

Re: AMT tweeters - explored by Critofur

These are the Dayton units?

[Squidspeak]

Re: AMT tweeters - explored by Critofur

Here are photos of the AMT3-4 and AMTPro-4 tweeters with their faceplates off:

Flickr photo gallery

[ATTACH=CONFIG]39984[/ATTACH][ATTACH=CONFIG]39985[/ATTACH]

More to come...

VERY strong magnets of course, and on the AMT4-Pro they are exposed - I experienced the clamping onto my AMT3-4 accidently, had to pull pretty hard to separate them.

Very,
very interested in these units. Hope you can provide measurements

[critofur]

Re: AMT tweeters - explored by Critofur

These are the Dayton units?

That's correct. Dayton AMT3-4 and AMTPro-4

Very,
very interested in these units. Hope you can provide measurements

Yes, I will definitely do at least some type of measurements on each of these units. As to whether or not I will get them in a BAFFLE, I'm not sure yet...

So, who knows how large of a "safety" capacitor I can can get away with, assuming I need one to measure at reasonable levels?

[donradick]

Re: AMT tweeters - explored by Critofur

Thanks! I've been looking at those units. Looking forward to FR and distortion.

[Jeff B.]

Re: AMT tweeters - explored by Critofur

Thanks! I've been looking at those units. Looking forward to FR and distortion.

I hope these measure well. I have refrained from posting on AMT's so far, but I will say a couple of things here. I have been sent three different samples of AMT drivers to test for the purpose of designing some speakers with them. Unfortunatley, none of them measured well enough to inspire me to really move forward much on it. I was disappointed with the really peaky top octave of a couple of models, but the distortion was especially troubling. This led me to wonder why these were showing up in so many commercial speaker designs these days. I think I have a couple samples coming from a different manufacturer and I am hoping they look better. I am interested to see what these look like when Chris measures them too. I did find one model that I could work well with and designed a two way using it that has very flat response, we'll see how all of that turns out.

Jeff

[Squidspeak]

Re: AMT tweeters - explored by Critofur

I hope these measure well. I have refrained from posting on AMT's so far, but I will say a couple of things here. I have been sent three different samples of AMT drivers to test for the purpose of designing some speakers with them. Unfortunatley, none of them measured well enough to inspire me to really move forward much on it. I was disappointed with the really peaky top octave of a couple of models, but the distortion was especially troubling. This led me to wonder why these were showing up in so many commercial speaker designs these days. I think I have a couple samples coming from a different manufacturer and I am hoping they look better. I am interested to see what these look like when Chris measures them too. I did find one model that I could work well with and designed a two way using it that has very flat response, we'll see how all of that turns out.

Jeff

I had planned on using The Airborne RT4001 in a 3-way but after Roman
measured them for me (4units) I am looking for a replacement and really hoping Chris
has some good things to show from the AMT3-4 it should be able to cross easier than
the Airbornes to my mid (Hi-Vi M5a)

[donradick]

Re: AMT tweeters - explored by Critofur

I hope these measure well. I have refrained from posting on AMT's so far, but I will say a couple of things here. I have been sent three different samples of AMT drivers to test for the purpose of designing some speakers with them. Unfortunatley, none of them measured well enough to inspire me to really move forward much on it. I was disappointed with the really peaky top octave of a couple of models, but the distortion was especially troubling. This led me to wonder why these were showing up in so many commercial speaker designs these days. I think I have a couple samples coming from a different manufacturer and I am hoping they look better. I am interested to see what these look like when Chris measures them too. I did find one model that I could work well with and designed a two way using it that has very flat response, we'll see how all of that turns out.

Jeff

That's what I was concerned about. From a marketing perspective, it's very rare to perform like the high priced units and
price at 50% less. We'll see what Chris meaures.

[Audiotorium]

Re: AMT tweeters - explored by Critofur

I hope these measure well. I have refrained from posting on AMT's so far, but I will say a couple of things here. I have been sent three different samples of AMT drivers to test for the purpose of designing some speakers with them. Unfortunatley, none of them measured well enough to inspire me to really move forward much on it. I was disappointed with the really peaky top octave of a couple of models, but the distortion was especially troubling. This led me to wonder why these were showing up in so many commercial speaker designs these days. I think I have a couple samples coming from a different manufacturer and I am hoping they look better. I am interested to see what these look like when Chris measures them too. I did find one model that I could work well with and designed a two way using it that has very flat response, we'll see how all of that turns out.

Jeff

This is pretty much the opposite of what you posted here.
I have used the Airborne RT4001 myself and I think it is a super nice tweeter.
Or maybe you are refering to the new Dayton's specifically(?).

[Paul W]

Re: AMT tweeters - explored by Critofur

If you would, run a tone sweep with a spectrum analyzer & look for sub-harmonics. The plain kapton diaphragm I measured was a great sub-harmonic generator! (AC diaphragms are coated with a slightly sticky substance and didn't exhibit the problem.)

[Jeff B.]

Re: AMT tweeters - explored by Critofur

This is pretty much the opposite of what you posted here.
I have used the Airborne RT4001 myself and I think it is a super nice tweeter.
Or maybe you are refering to the new Dayton's specifically(?).

There's been quite a bit posted in the two years since that thread. That's the problem with people going back and grabbing old posts and threads at times. Since then there was the thread where I received my second sample and it measured much more like Dennis' and Paul's samples, showing some concerning inconsistencies from driver to driver. This is the same thing that Roman posted on too. And although I posted that distortion was relatively decent, it is still nowhere near what we would expect from a good dome tweeter. Ultimately the RT4001 was the driver I ended up using in a design, and samples of other models were much less usable in my opinion. The thing now is that my name ends up on these designs. As a result I have become very picky about where my name ends up. I simply won't associate it with a speaker I feel is not a good reflection on me as a designer, so sometimes some drivers just get rejected as good design candidates. However, because people make a living selling these things I often refrain from saying negative things about drivers that I personally don't like out of respect for some people in the business. On the other hand I never mind promoting drivers that I believe are really excellent.

[Audiotorium]

Re: AMT tweeters - explored by Critofur

There's been quite a bit posted in the two years since that thread. That's the problem with people going back and grabbing old posts and threads at times. Since then there was the thread where I received my second sample and it measured much more like Dennis' and Paul's samples, showing some concerning inconsistencies from driver to driver. This is the same thing that Roman posted on too. And although I posted that distortion was relatively decent, it is still nowhere near what we would expect from a good dome tweeter. Ultimately the RT4001 was the driver I ended up using in a design, and samples of other models were much less usable in my opinion. The thing now is that my name ends up on these designs. As a result I have become very picky about where my name ends up. I simply won't associate it with a speaker I feel is not a good reflection on me as a designer, so sometimes some drivers just get rejected as good design candidates. However, because people make a living selling these things I often refrain from saying negative things about drivers that I personally don't like out of respect for some people in the business. On the other hand I never mind promoting drivers that I believe are really excellent.

Understood (I didn't see your follow-up thread).
I agree with you that when designing with very inconsistent drivers, it is better to not share/publish them and thus avoid a lot of frustration.
Thanks for your input on this Jeff.

[r-carpenter]

Re: AMT tweeters - explored by Critofur

I actually don't agree with not publishing data if the driver isn't performing well.
There are reasons to be careful so one does not needlessly tarnish the reputation of driver manufacturer. Myself, I would always check every part of the system. If the measured data looks bad, I'd throw a known driver on the baffle to make sure there are no missed issues. Only then I'll post the data.
Problem with not posting the info is this: Squid purchased 4 units of Airborn. He's out of $300 or so. Airborn declares frequency response that's entirely different from what it actually does. So, who's money is going to who's pocket for what reason? I picked up a pair of Visaton KE tweeters based on the manufacturer's description. Also out of $300 for the intended purpose. So, the list goes on and I am pretty sure other DIYers made same mistakes based on provided and inaccurate data. In case of Airborne the consistency of measured units appears to be an issue also, all tho the over all ragged and upped top octave looks similar on all independent tests.
I think one of the advantages of our community is DIYers is sharing of information. No reason to hide potential problems with driver units.

[craigk]

Re: AMT tweeters - explored by Critofur

well said. Visaton can handle not getting 300.00 of some ones hard earned money better than you or I can handle giving it to them for some they misrepresented to start with. I do understand your view Jeff. another website published info and opinions on morel drivers. I have read and heard numerous people state that they would never buy morel products because of this, and morel makes some great drivers that sound very good, despite distortion numbers.