Heil AMT (Air Motion Transformer) Tweeter

Heil AMT Tweeter

There are different models of AMT (Air Motion Transformer) tweeters by Heil. The one featured here was used in the ESS Performance Series PS-920 and PS-820 loudspeakers. According to Heil’s brochure, this tweeter was crossed at 2kHz. All the measurements below were made without any crossover unless otherwise stated.  

Heil AMT in a 7 Liters Box (Baffle Width = 6.75″)

Fig 1 – Black plot = RAW. Red plot = 2.6kHz (24dB/oct).
Mic 1 meter, on axis. Impulse Window=5msec. No Smoothing applied.

RAW Heil AMT Cumulative Spectral Decay (Baffle Width = 6.75″)

Fig 2 – Rise Time = 0.1ms, Window = 1.3ms ( 769Hz ), Time Range = 1.0ms.

RAW Heil AMT Toneburst Energy Storage (Baffle Width = 6.75″)

Fig 3 – Heil AMT Toneburst Energy Storage.

RAW Heil AMT Spectrogram (Baffle Width = 6.75″)

Fig 4 – Heil AMT Spectrogram

RAW Heil AMT Step Response

Fig 5 – Step Response (No Crossover)

Heil AMT Impedance

Fig 6 – Heil AMT Impedance Sweep