MUNDORF AMTU40W1.2

Mundorf AMTU40W1.2: small AMT with 4 Ω, 92 dB, usable from 3,500 Hz up to 40 kHz

An AMT in a 55 x 55 x 45 mm format: the Mundorf AMTU40W1.2 is the most compact model in the AMT U series and by design a pure tweeter. The figures: 4 Ω impedance, 92 dB sensitivity at 2.83 V and 1 m, working range from 3,500 Hz with 12 dB/oct., response up to 40 kHz, neodymium magnet. The upper limit well beyond the audible range makes it interesting for high-resolution sources and for use as a super tweeter.

The short, almost square foil has one consequence worth knowing: it hardly narrows vertical dispersion and radiates wide in both planes, unlike the tall AMTs in the series. In return its area is small, which sets the lower limit at 3,500 Hz. The air-motion drive itself works as in the large models, with a pleated foil and conductor tracks in the magnetic field, and delivers the typical AMT qualities: low moving mass, clean decay and little distortion in the upper treble.

Use and enclosure

The AMTU40W1.2 belongs in three-way systems above a midrange dome or a small cone midrange that works cleanly up to 3,500 Hz and beyond, or in two-way boxes with small mid-woofers that do not yet beam that high. Use as a super tweeter above a full-range driver or a horn-loaded system that rolls off at the very top is equally plausible. The crossover must not sit below 3,500 Hz, and the high-pass needs at least 12 dB/oct.; 24 dB/oct. is the safe choice with a diaphragm this size.

The 4 Ω rating matters for crossover design and amplifier choice: 2.83 V into 4 Ω is 2 W, so the amplifier must be able to drive the load continuously. The small cut-out fits almost anywhere, even close to the midrange, which helps the transition at 3,500 Hz because the centre-to-centre spacing stays short. At 42.audio you get the datasheet PDF and the driver database with the larger U-series models, in case you want to cross lower after all.

What to look out for

• 4 Ω impedance: 4 Ω stable amplifier, calculate the crossover with 4 Ω.
• 92 dB at 2.83 V/1 m: matches hi-fi midranges without a large voltage divider.
• Crossover no lower than 3,500 Hz, high-pass at least 12 dB/oct.
• 55 x 55 x 45 mm: small cut-out, short distance to the midrange possible.
• Response up to 40 kHz, suitable as a super tweeter.

Frequently asked questions

Mundorf AMTU40W1.2: manufacturer, spellings and classification

Mundorf is Mundorf EB GmbH of Cologne, Germany, known for crossover components and the air motion transformer tweeters of the AMTU series. The AMTU40W1.2 is an air motion transformer (AMT) tweeter from the AMT U series, available from 42.audio, Mundorf dealer in Germany, with datasheet and full specifications in the driver database.

At 42.audio you get the MUNDORF AMTU40W1.2 with datasheet PDF, all key data in the driver database. More drivers from this manufacturer: Atlas Mundorf.