X-AMT: The Constant Directivity Waveguide for AMT

X-AMT Waveguide for Mundorf U series

The mundorf U series is the new lineup of Mundorf AMT, reducing the maximum model range of AMT tweeters which cover all possible applications in home and studio audio application.

The waveguide is suitable for no “with faceplate” AMT version :

Unlike a planar ribbon tweeter, the AMT’s diaphragm has a bellows-like pleated shape. Using a folded sheet of polyethylene terephthalate film with metal etching, the AMT moves air sideways in a perpendicular direction.

As ribbon and AMTs can’t generally be crossed very low, so we use a relatively small waveguide chosen in function of desired crossover and mid-woofer used (typically 6.5" or 7.5/8").

Simulated in FEA, the waveguide exhibits an X-Shape-like form and incorporates a tiny fin to mitigate the throat resonances that AMTs or ribbon tweeters often experience in waveguides.

WaveGuide AMT SPL
AMT is directly mounted by the rear, using woofer hole AMT SPL

Features

Measurement of the 17.1cm version on Mundorf AMTU80W1.1

SPL on U80 17cm AMT SPL
Horizontal AMT SPL
Vertical AMT SPL

The SPL is linear, and allow a easy crowwover even in passive filtering.

There is a vertical beam due to the AMT’s throat height, which can be seen in the vertical polar, but it is well-controlled in this design, partially thanks to the tiny fin.

If needed a “hyper constant” version can be asked, the difference will be only at the end of horizontal polar :

Horizontal AMT SPL

Price and size:

All waveguides are provided with full returns and spray putty, ready to be painted. The height depends on the chosen AMT and width.

The full returns add a 25mm roundover to the top and both sides of the waveguide. The bottom remains free to allow for a close mounting of the mid-woofer.