AMT Loudspeaker Chassis👍
The AMT (Air Motion Transformer) is a development of the German physicist Dr. Oskar Heil. It is a tweeter-midrange driver that is low in distortion and has a high efficiency. Depending on the model, the frequency range starts at about 750Hz and goes up to 32000Hz (-6dB). The high efficiency is achieved by a concertina-like membrane, which is excited in a strong magnetic field to vibrate.
The AMT was marketed on a large scale by the US company ESS, but had quality problems and is hardly used today.
Fun Facts: - Efficiency (98-100dB) - DC resistance 3.2 Ohm - resonance frequency 950 Hz - nominal impedance 4 Ohm - use only from 1000 Hz - high impulse speed - sometimes difficult configuration with bass drivers due to high AMT efficiency - the slight increase in high frequencies is often attenuated by blocking circuits
models: AMT 1 AMT 2
Diaphragm: - Kapton plastic - concertina folding - Connections (non-binding, different assignments possible):
(+) Pole: Green / Yellow / Blue (-) Pole: Black / Violet / Brown / Red
- correct polarity can be determined by noise, if polarity is correct the level is higher
Alternatively, the German company Mundorf offers a range of very high quality models.
The AMT from ESS was used e.g. in these models:
- ESS AMT 1 Tower
- ESS Connoisseur Series AMT 450
- ESS PS-81
- ESS PS-61
- Myro Concert
- Myro Grand Concert
- Myro Concert Monitor
- Myro Heaven's Gate (single speaker with 3 x AMT per box)
- Myro Floor Monitor
- Myro Pro Fidelity 3.1
AMT models from Mundorf are used here, for example: