The One and Only Full Range AMT

[RayCtech]

Originally Posted by jkeny

Fantastic, Ray, I wasn't aware that you had built these yourself - I thought that the AMT's were a commercial driver that you had mounted into horns!
This is DIY par excellence! A viable new DIY driver based on AMT theory is not something trivial - I commend your technical prowess
Looking forward to the details of this build

PS Your complete system would appear to be as resolving as can be achieved with current technology - SDTrans192 SD card player -> Sabre DAC (to be decided) -> Balanced JFET LU1014D poweramp -> AMT speakers - Awesome !!!!!

Thanks John, and thanks to you everything will be running from LiFePo4 batteries very soon...

[feyrerm]

Originally Posted by RayCtech

The patents Oskar Heil issued are easy to find and are possibly the only help you will get...

When I was searching for someone that could manufacture my diaphragms I was amused time after time..

I got some samples of AMT diaphragms, and when I compared those with the patent papers - they was bluecopies of the drawings in the patents.

Due to my implementation of AMT´s are my own and I have used my own "head" - my AMT´s are more different then like all other implementations.
The layout of the diaphragms are so different from the patents that the manufacturer of the diaphragms was sure they could not work.

And as I am using materials that never have been used in AMT´s before, the manufacturer had to implement a new production process and both the film and the conducting materials had to be special ordered.
As my diaphragms only are 12.5 micron thick I was told time after time that a AMT could not be made, and certainly not a 560 cm2 diaphragm that was intended for playing bass. I was also told that it was not possible to use so strong magnets as the neodym N52 magnets I use either together with the thin diaphragms.
All this may be true if I had copied the patents.

But the diaphragms are the easiest part.

The holding/folding container for the diaphragms was also very difficult to find someone to manufacture.
They are made of good old "pertinax" and are 3D CNC machined by a company in Germany.

I have two other AMT´s finished as designs - a 2000 cm2 bass transducer with Xmax of 2mm, and a complementary midrange / treble AMT with a expected bandwith of 50kHz or more.

As the AMT´s I have now are extremely difficult to assemble they are not yet suitable for DIY.

Wow sounds like a lot of engineering on your part went into your design! It never ceases to amaze me the level of expertise that can be found here on this forum.

I will check out the patents. I really love to explore the DIY aspects of these things. I have done planars, ribbons, and esl's. Mostly just for fun and testing and I would really love to attempt something like this. Thanks for the input.

[jkeny]

Originally Posted by RayCtech

Thanks John, and thanks to you everything will be running from LiFePo4 batteries very soon...

I'm glad I was able to help in some small way - going off grid will hopefully prove to be another significant improvement? Let us know your findings - should be interesting in such a resolving system!

[RayCtech]

Here is a measurement i did now with XTZ room analyzer.
It is measured with one AMT in a horn cabinet designed for five AMT drivers.
The measured driver have not the latest and most linear diaphragm.

I will come back with better measurements when I get the proper measuring equipment running again, and I have prepared drivers with the final diaphragms..

[RayCtech]

I have received some questions regarding the availability of the AMTs and 8" drivers.

Both the AMTs and 8" drivers was originally designed to be commercial products.
I will now finish some of the drivers as demo units and investigate if there are some companies that will take over the concepts.

The sound quality are remarkable and those that have heard them have never heard anything close.
The "strangest" with the AMTs are how good they play bass - this was my worry, but when I solved the resonances at lower frequencies bass was suddenly the best part...
Even if they drop in level above 18kHz (due to cancelations due the size) there is no distortion and they play the highs better than AMTs that goes to 35kHz.
More detail, more soundstage, more dynamic etc..

[vuki]

[Henkjan]

now this is something to follow....

[c2cthomas]

Originally Posted by feyrerm

Wow sounds like a lot of engineering on your part went into your design! It never ceases to amaze me the level of expertise that can be found here on this forum.

I will check out the patents. I really love to explore the DIY aspects of these things. I have done planars, ribbons, and esl's. Mostly just for fun and testing and I would really love to attempt something like this. Thanks for the input.

3832499 + 6205228 + 6111970 + PAT2PDF - Free PDF copies of patents: Download and print!

"Wow sounds like a lot of engineering on your part" - This much more than that I was not sure if I would see something like this during my lifetime. This is some wonderful engineering as an art form + Inspiration + tons of trial and error + perhaps a little luck (we all need some) but most of all belief and desire to reach a seemingly unreachable goal. This is like being Sir Edmond Hillary being 1st to top Mt. Everest. Of course Sir Edmond could not have accomplished that feat without the aid and guidance of Tenzing Norgay.

However, this claim still needs independent verification and long term reliability testing in it's intended environment - and I have a great place in mind for that.

[c2cthomas]

Originally Posted by RayCtech

I will now finish some of the drivers as demo units and investigate if there are some companies that will take over the concepts.

This is more easily said than done. You will face the "not invented here" syndrome or some companies that might buy it just to kill it so that it will not be around to compete with their devices.

You seem to be very experienced in the area of design though so it is most likely that I am telling you something that you already know.

[RayCtech]

There is one aspect with the AMT that might make it even more interesting..
There are four "voicecoils" - each of 8 ohm.
The AMT can be configured as a 2 ohm, 8 ohm or 32 ohm device.
Pure resistive in all three configurations.

Four AMTs would be needed to get full level down to 20Hz.

If configured for 32 ohm and four AMTs connected in series - you then have a 128 ohm pure resistive speaker, and if you use eight AMTs in a line source you have a 256 ohm pure resistive speaker.
Connected to a valve / tube OTL amplifier able to deliver 100 - 200 Volt and you have something interesting...