MUNDORF AMTU40W1.2 — AMT-Tweeter mit Frontplatte
92 dB Sensitivity (2.83 V/1 m) · 4 Ω
Technical data
- Impedance: 4 Ω
- Sensitivity: 92 dB (2.83 V/1 m)
- Application: ab 3500 Hz (12 dB/Okt.) bis 40 kHz
- Dimensions: Ø80xZ48 mm
- Magnet: Neodymium
Datasheet (PDF) · Manufacturer page
Series: AMT U · Part no.: 42A-CHS-AT-MUN-0002
Mundorf AMTU40W1.2-C: compact AMT tweeter with round faceplate, 92 dB and 4 Ω
The Mundorf AMTU40W1.2-C is the smallest member of the AMT U series in this range and ships with a round faceplate of 80 mm diameter already fitted. The C in the name stands for exactly that version: you cut a round hole in the baffle, drop the tweeter in and get a clean, closed front without any extra adapter plate. Mounting depth stays at a modest 48 mm, which keeps slim cabinets and on-wall speakers on the table.
An air motion transformer works differently from a dome. A pleated foil with printed conductor tracks sits in the magnetic gap, and the pleats squeeze together and open again. Air is pushed out of the folds faster than the foil itself moves. The result is very low moving mass, clean transient behaviour and a bandwidth that reaches 40,000 Hz on the AMTU40W1.2-C. The neodymium magnet keeps the unit small and light, and sensitivity is 92 dB (2.83 V/1 m) at 4 Ω.
Use and enclosure
The usable range starts at 3,500 Hz with a slope of at least 12 dB per octave. Treat that as the lower limit rather than the recommendation: if you plan to drive the AMT at serious levels in a domestic system, cross over higher or pick a steeper filter so the foil is not stressed near its resonance. That makes the AMTU40W1.2-C a match for a mid-woofer that stays clean well into the upper midrange, typically a smaller driver in a 2-way design, or the third way in a 3-way system with a dedicated midrange.
An AMT radiates wide horizontally and narrower vertically than a dome, because the foil is tall and narrow. On the AMTU40W1.2-C the element is compact, so vertical beaming stays moderate and listening height is not critical. The faceplate doubles as a small baffle and gives a defined transition into the cabinet front.
What to look out for
- 4 Ω impedance: account for the low load in passive crossovers and at the amplifier.
- Round faceplate, 80 mm diameter, 48 mm mounting depth: fits slim enclosures.
- 92 dB at 2.83 V: for a 4 Ω driver that is roughly 3 dB less when referenced to 1 W.
- Lower limit 3,500 Hz at 12 dB per octave: never cross lower, rather go steeper.
- Neodymium magnet: low weight and a compact motor without a large ferrite ring.
Frequently asked questions
What crossover frequency makes sense for the AMTU40W1.2-C?
The lower limit is 3,500 Hz with 12 dB per octave. If the tweeter goes into a 2-way speaker that will be played loud, crossing well above that limit or using an 18 or 24 dB per octave filter is the safer choice. The mid-woofer then has to stay clean up to that point.
Can I run the AMTU40W1.2-C from a normal hi-fi amplifier?
Yes, 4 Ω is no issue for most amplifiers. With a passive crossover you have to include the impedance in the filter design and, given the 92 dB sensitivity, you will usually need a voltage divider to match the level to the mid-woofer.
How does the AMTU40W1.2-C differ from the larger AMT U models?
The larger models carry a longer foil, offer higher sensitivity and can be crossed lower, but beam more in the vertical plane. The AMTU40W1.2-C is the choice when space is tight, the crossover sits high anyway and dispersion above and below the axis should stay relaxed.
Mundorf AMTU40W1.2-C: 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-C 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-C with datasheet PDF, all key data in the driver database. More drivers from this manufacturer: Atlas Mundorf.
Specifications
| Manufacturer | MUNDORF |
| Category | AMT Tweeter |
| Series | AMT U |
| Magnet | Neodymium |
| Impedance (Ω) | 4 |
| Sensitivity (dB) | 92 |
| Frequency from (Hz) | 3500 |
| Frequency to (Hz) | 40000 |