AMT vs. Ribbon

[Cyan]

Hi, i'd like to know what you think about the differences between ribbons and amt tweeters.
I want to know about the specific differences, and if you think wich one of the 2 is overall better (if it's possible to say that).

[ackcheng]

I remember when I search for AMT vs RAAL before on thus forum. Many prefer RAAL saying that it is more neutral.

[Borat]

AMT is a very clever way of packaging the magnetic field around the diaphragm. a ribbon should theoretically be better but require a much more powerful magnetic circuit as well as a transformer.

so i would say that AMT for price/performance and ribbon for cost no object ultimate high end.

but this is just theoretically. i don't have any listening experience here.

[Variac]

The open backed AMT's are bipoles whereas an open backed ribbon would be a dipole.
AMT's are in phase front and back I think, unlike most drivers, including ribbons.

[Cyan]

Originally Posted by Borat

AMT is a very clever way of packaging the magnetic field around the diaphragm. a ribbon should theoretically be better but require a much more powerful magnetic circuit as well as a transformer.

so i would say that AMT for price/performance and ribbon for cost no object ultimate high end.

but this is just theoretically. i don't have any listening experience here.

Ok, but i find the cheapest amt at 300$. While you the fountek neocd 3.0 can be found for 90$ (it should be an "average" ribbon).

[Cyan]

Originally Posted by ackcheng

I remember when I search for AMT vs RAAL before on thus forum. Many prefer RAAL saying that it is more neutral.

I found them in very top end systems. Are them maybe the best ribbons out there?

[Keith Taylor]

Originally Posted by Variac

The open backed AMT's are bipoles whereas an open backed ribbon would be a dipole.
AMT's are in phase front and back I think, unlike most drivers, including ribbons.

This subject has been covered on this forum before. On one audio half cycle the pleats are compressing air on one side of the diaphragm and rarifying it on the other. For the other half cycle (drive voltage sign reversal) the oposite applies. Thus the AMT is no different to a cone etc, making it a dipole when unenclosed.

AMT's and ribbons share one characteristic in that they are acoustically large in the vertical dimension and small in the horizontal dimension. This means they are going to have broader directivity horizontally than vertically. As an AMT can displace more air than a ribbon for the same motion it can be crossed over at a lower frequency for a given SPL. These are theroretical differences, but like most things in audio the final arbiter is the "earometer"
Keith

[cuibono]

Agreed with the above. AMT's also have a higher max power handling and SPL (at least the Beyma TPL-150). AMTs are much less fragile than ribbons. I would note that being able to cross them lower (sometimes much lower) can be very useful if you're concerned about lobing at the crossover and power response.

[Variac]

Thanks for straightening me out Keith

[tinitus]

Two things puzzles me with AMT

One is the front grille
If it was mounted on a dome tweeter or any other kind of driver, noone would buy it
And there would be good arguments why not

The other is less obvious
Its the folding of the diaphragm
Im sure theres lots of things going on in such a folded design
Phase issues maybe, or other nasty things

But it seems the avantages of the AMT are enough to keep in front

Technically, planars with edged coils on the diaphragm should be superiour
But fore whatever reason its not
But maybe it will be, in time