Direct Metal Mastering (DMM) is the name for a technology in record production that was introduced in the early 1980s by the record company Teldec. With DMM, the stamper is made from a metal-coated stainless steel plate. The cutting stylus cuts directly into the metal surface – hence the name Direct Metal Mastering.
How does direct metal mastering differ from classic lacquer cutting?
First the similarities: Records are pressed into hot vinyl according to the waffle iron principle. For this purpose, negatives of the sound grooves of the A and B sides are clamped into the press as “punches”.
To create these so-called press dies or press stamps, one first needs a positive image of the respective side of the plate. This so-called “nut” is cut into a blank by a special cutting machine. In the process, a cutting stylus is set in vibration by electromagnetic signals, similar to the movement of a loudspeaker membrane. In this way, it cuts the image of the audio signal into the surface of the blank.
Here come the differences: with classic lacquer cutting, the cut is made into a lacquer foil, while with direct metal mastering, a very hard diamond stylus cuts into a hard metal blank with a copper or cadmium surface.
In this way, Direct Metal Mastering creates a metal master from which the press matrices can be generated, without any further intermediate steps such as “father” or “mother”.
What are the advantages and disadvantages of the DMM process?
DMM pressings, such as the Beatles reissues from the 1990s, usually have less background noise and less crackling and popping, so-called “impulsive noise”. In addition, the high frequencies are usually reproduced more brilliantly and with less measurable distortion. Furthermore, the DMM process allows for longer running times of a record side. Further advantages can be seen in lower pre- and post-echoes, which result from springback deformations during cutting.
Since the DMM cutting process uses much harder foil material than classical lacquer cutting, much greater force must be applied. As a result, DMM pressings often have a somewhat weaker bass effect, as the low frequencies in particular require large excursions in the grooves. The brilliant highs and weaker bass can result in a sound image that many listeners find harsh. However, experienced cutting technicians also create excellent sounding records using the DMM process.