Direct metal mastering

Direct metal mastering (DMM) is an analog audio disc mastering technique jointly developed by two German companies, Telefunken-Decca (Teldec) and Georg Neumann GmbH, toward the end of the 20th century after having seen the same technology used by RCA Princeton Labs for its SelectaVision videodiscs in the late 1970s.

This preserves the original modulation details in the groove walls much better, especially those involved with sudden fast attacks (transients).

Examination of early DMM discs revealed what appeared to be a high frequency modulation in the groove, thought to be caused by the use of an ultrasonic carrier tone.

In fact, there was no carrier tone and the modulation was simply caused by the vibration (squeal) of the cutter head as it was dragged through the copper disc.

Rather than having to electroform a master (or "father"), mother and then stampers (the traditional "three-step process"), the DMM copper disc serves as the 'mother".

The lack of obvious contour in the groove area on the face of the record closely replicates the original disc surface and reduces playback errors.

As of 2009 there are seven publicly-usable DMM cutting facilities left in the world, all located in Germany, Netherlands, or Czech Republic.

[2] The US lost its last DMM cutting facility in 2005 with the demise of New York City-based record manufacturer Europadisk LLC.

Although Neumann produced, demonstrated and promoted a successful prototype CD Mastering unit for DMM, it never went into commercial production.

With the groove being cut straight into a metal foil, DMM therefore reduces the number of plating stages in the manufacturing process.