<s>
The	O
Air	B-Device
Motion	I-Device
Transformer	I-Device
(	O
AMT	O
)	O
is	O
a	O
type	O
of	O
electroacoustic	O
transducer	B-Algorithm
.	O
</s>
<s>
Invented	O
by	O
Oskar	O
Heil	O
(	O
1908	O
–	O
1994	O
)	O
,	O
it	O
operates	O
on	O
a	O
different	O
transduction	B-Algorithm
principle	I-Algorithm
from	O
other	O
loudspeaker	O
designs	O
,	O
such	O
as	O
moving	O
coil	O
,	O
planar	O
magnetic	O
or	O
electrostatically-driven	O
loudspeakers	O
,	O
and	O
should	O
not	O
be	O
confused	O
with	O
planar	O
or	O
true	O
ribbon	O
loudspeakers	O
.	O
</s>
<s>
In	O
contrast	O
to	O
a	O
planar	O
ribbon	O
loudspeaker	O
,	O
the	O
diaphragm	O
of	O
the	O
AMT	O
is	O
of	O
pleated	O
shape	O
similar	O
to	O
a	O
bellows	B-Algorithm
.	O
</s>
<s>
The	O
air	B-Device
motion	I-Device
transformer	I-Device
with	O
its	O
sheet	O
film	O
equally	O
exposed	O
at	O
180°	O
behaves	O
as	O
a	O
dipole	O
speaker	O
,	O
exciting	O
front	O
and	O
rear	O
sonic	O
waves	O
simultaneously	O
.	O
</s>
<s>
The	O
speed	O
of	O
the	O
air	O
as	O
it	O
leaves	O
the	O
diaphragm	O
is	O
approximately	O
five	O
times	O
faster	O
than	O
the	O
speed	O
of	O
the	O
actual	O
driver	O
structure	O
,	O
hence	O
the	O
name	O
Air	B-Device
Motion	I-Device
Transformer	I-Device
.	O
</s>
<s>
Consequently	O
,	O
the	O
most	O
common	O
use	O
for	O
the	O
AMT	O
driver	O
in	O
consumer	O
electronics	O
today	O
is	O
as	O
a	O
midrange-tweeter	O
or	O
tweeter	B-Device
in	O
high-end	O
multi-driver	O
speakers	O
,	O
sometimes	O
paired	O
with	O
horns	O
,	O
or	O
in	O
the	O
case	O
of	O
Precide	O
's	O
speaker	O
products	O
,	O
with	O
an	O
upward-firing	O
woofer	O
driver	O
.	O
</s>
<s>
In	O
the	O
tweeter	B-Device
market	O
,	O
the	O
AMT	O
competes	O
against	O
electrostatic	O
,	O
ribbon	O
and	O
electrodynamic	O
tweeters	B-Device
.	O
</s>
<s>
While	O
apparently	O
very	O
good	O
as	O
a	O
mid-tweeter	O
or	O
full	O
tweeter	B-Device
,	O
the	O
AMT	O
is	O
not	O
commonly	O
employed	O
in	O
lower	O
frequency	O
speakers	O
.	O
</s>
<s>
Appearing	O
as	O
a	O
short	O
lopped	O
pyramid	O
,	O
the	O
system	O
combined	O
the	O
AMT	O
transducer	B-Algorithm
with	O
a	O
10-inch	O
ported	O
woofer	O
.	O
</s>
<s>
From	O
2006	O
to	O
2008	O
,	O
air	B-Device
motion	I-Device
transformers	I-Device
were	O
made	O
available	O
directly	O
to	O
the	O
European	O
consumer	O
as	O
the	O
company	O
closed	O
its	O
doors	O
in	O
California	O
and	O
relocated	O
to	O
Germany	O
.	O
</s>
