.Dr. Oskar Heil, noted physisist and inventor of the Field Effect Transistor, began his research into loudspeaker design, not with abstract theory of how a loudspeaker should work, but with a study of the peculiarities of the human listening aparatus. The result of this intensive year-long research program led to his discovery of the principle on which the Oskar Air Velocity Transformer is based. By applying this principle to the design of a loudspeaker diaphragm, he was able to achieve a revolutionary breakthrough in solving the fundamental problems of diaphragm mass, inertia and self resonance. In the following, we describe the results of Dr. Heils research and how it led to the development of the Heil Air Motion Transformer speaker. 

Details and description

Test Reports

Prices in SFR in Switzerland

 Oskar A.V.T. ( AMT) Kithara Loudspeaker.
The bass unit is mounted facing upwards to ensure the best phase relaitionship with the high frequency OSKAR A.V.T. ( AMT)


Heil Kithara Heil A.M.T. ®

Kithara Floor plate

measurement 50 x 50 x 4 cm
Possibilitiy for 8mm Spikes or wheels

Speaker elements: 1 A.M.T. mid range - tweeter 650 - 23000 Hz

Heil Kithara with floor plate

Floor plate is Optional

  1 25 cm bass unit 28-700 Hz.
Frequency response: 28-23000 Hz +- 5 dB
Sensitivity: 94 dB 1 W 1 meter
Impedance: 4 ohm minimum
Cabinet finish: oiled walnut, cherry, or black, Maple wood veneer
Dimension: 40 x 40 x 110 cm including A.M.T.

Weight: Kithara

Wight Floor plate

ca. 35 Kg.

ca 7 Kg.


The Oskar AVT / Heil A.M.T. ® Aulos Bookshelf speaker

An intensive study of the different woods has made it possible to achieve the acoustic details in the Bass-region and to match the game-partner Heil A.M.T.
The Heil A.M.T. works from 1050 Hz to 23 kHz with its almost mass less membrane.
The positioning of the speaker is easy, since the phase correct dispersion has this large advantage over other speakers in the market.
The Aulos Bookshelf has the advantage of an uncritical load-behaviour as well as a high efficiency.
The low Mass of the Heil A.M.T. drivers guarantees a balanced sound-picture also with rather low levels.
The Heil A.M.T. moves the air 5 x faster than conventional electrostatic-, Magnetostat - or dynamic loudspeakers,

Technische Daten: Heil A.M.T. Air-Motion-Tranformer Aulos Lautsprecher
Principe 2 way, Bass reflex
Mid-high frequency Heil A.M.T.® 1050 - 23000 Hz
Woofer 160 mm Ø 45-1050 Hz
Frequency 45-23000 Hz
Cross over point 1050 Hz
Efficiency 91 dB 1 W 1 Meter
Impedance: Minimum 4 Ohm
wood veneer Maple, cherry, walnut and black ash, Grill Black
measurements W x D x H 205 x 275 x 392 mm
Weight 9.9 Kg.



dark oak





The Oskar AVT / Heil A.M.T. ® Subwoofer for Aulos Bookshelf speaker
In place of a speaker stand you can improve the bass
of the Aulos with the specially designed subwoofer.
The Aulos is simply fitted on the top of it, and is then
connected to with the two speaker wires.
The best result was achieved with a down firing bass
in a closed box and slightly compressed in a well calculatedcabinet .
Internal we use the resonators as with all other models.
WxDxH:210 x 275 x 565 mm
Feet: 225 x 290
Weight app. 13.-- Kg.
SW- Cherry bookshelf
SW - Maple bookshelf
SW - Oak bookshelf



The Heil A.M.T.® Syrinx is based on the experiences made with the Heil A.M.T.® Kithara and Aulos, which are successfully on the market for over 10 Years. The extensive studies of wood combinations and other acoustical factors have delayed the launching of this speaker for more than one Year. Its modern exterior design comes from TELOS of Berlin, whereas the acoustical refinements to match the sound impressions of the other two models have been made by Precide SA, with the great help of Mieko Dürrenmatt, (my wife) As the other speakers, the Syrinx uses the Heil A.M.T. Made by Precide, which covers the important frequency range from 1000 Hz on up to 23 KHz. The bass driver is a paper cone unit with an inverted dust cap and is working as a bass reflex. The alignment between the bass and the Heil is very phase coherent, as a matter of fact; one could say that it is a point source speaker. The Bass unit faces app. 45° upwards and the Heil driver is located in such a way, that the two units match perfectly. The X over is completely electrically separated, so that bi-wire or bi-amplification does not present any problem at all. The unit comes with pin points and specially made plates, so that the floor will not be damaged. The available wood veneers are: Cherry, Maple and back ash. Warranty is 5 Years and instructions are in four languages, English, German, Italian and French.

1 A.M.T. mid range tweeter 1000 - 23000 Hz
  1 15 cm bass unit 40 - 1000 Hz
Frequency response: 40 - 23000 Hz
Sensitivity: 90 dB 1 W 1 meter
Impedance: 4 ohm minimum
Cabinet finish: black maple and cherry
including grill:
W x D x H 270 front 105 back x 270 x 910 mm
Weight: 14 Kg.

Oskar A.V.T. ( AMT) Aulos
The bass unit is mounted in a 45° angle to ensure the best phase relaitionship with the high frequency OSKAR A.V.T. ( AMT)

1 A.M.T. mid range tweeter 1000 - 23000 Hz
  1 15 cm bass unit 40 - 1500 Hz
Frequency response: 45 - 23000 Hz
Sensitivity: 89 dB 1 W 1 meter
Impedance: 4 ohm minimum
Cabinet finish: Oiled cherry, maple, or black veneer
including grill:
23 w x 30 d x 50 h cm
Weight: 8.7 Kg.

the - signal the + signal open and close and how it works
Membranen Details

Precide SA
via V. Vela 33

CH 6834 Morbio Inf.

Tel. 091 6831734 - 35

FAX 091 6836679

E-mail info@precide.ch