Direct Metal Mastering
Encyclopedia
Direct Metal Mastering is a vinyl record manufacturing technology by TELDEC
. Records manufactured with this technology are often marked by a "DMM" logo on the outer record sleeve.
The cutting lathe
for DMM engraves the audio signal
directly onto a copper-plated master disc, instead of engraving the groove into a lacquer-coated aluminum disc. 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.
There is one drawback of this approach and that is because of the modulation arising from this cutting method, criticisms have arisen of the sound of such 'DMM' records. They are often labelled as bright or edgy.
The Direct Metal Mastering technology addresses the lacquer
mastering
technology's issue of pre-echoes during record play, caused by the cutting stylus unintentionally transferring some of the subsequent groove wall's impulse signal into the previous groove wall. In particular, a quiet passage followed by a loud sound often clearly revealed a faint pre-echo
of the loud sound occurring 1.8 seconds ahead of time (the duration of one revolution at 33 rpm). This problem could also appear as post-echo, 1.8 seconds after a peak in volume.
Another improvement is noise reduction
. The lacquer mastering method bears a higher risk of adding unwanted random noise
to the recording, caused by the enclosure of small dust particles when spraying the silvering on the lacquer master, which is the necessary first step of the electroplating
process for reproduction of the master disc. As the DMM master disc is already made of metal (copper), this step is not required, and its faults are avoided.
Teldec
The Teldec is a German record label in Hamburg, Germany. Today the label is a property of Warner Music Group.-History:...
. Records manufactured with this technology are often marked by a "DMM" logo on the outer record sleeve.
The cutting lathe
Lathe
A lathe is a machine tool which rotates the workpiece on its axis to perform various operations such as cutting, sanding, knurling, drilling, or deformation with tools that are applied to the workpiece to create an object which has symmetry about an axis of rotation.Lathes are used in woodturning,...
for DMM engraves the audio signal
Audio signal
An audio signal is an analog representation of sound, typically as an electrical voltage. Audio signals may be synthesized directly, or may originate at a transducer such as a microphone, musical instrument pickup, phonograph cartridge, or tape head. Loudspeakers or headphones convert an electrical...
directly onto a copper-plated master disc, instead of engraving the groove into a lacquer-coated aluminum disc. 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.
There is one drawback of this approach and that is because of the modulation arising from this cutting method, criticisms have arisen of the sound of such 'DMM' records. They are often labelled as bright or edgy.
The Direct Metal Mastering technology addresses the lacquer
Lacquer
In a general sense, lacquer is a somewhat imprecise term for a clear or coloured varnish that dries by solvent evaporation and often a curing process as well that produces a hard, durable finish, in any sheen level from ultra matte to high gloss and that can be further polished as required...
mastering
Audio mastering
Mastering, a form of audio post-production, is the process of preparing and transferring recorded audio from a source containing the final mix to a data storage device ; the source from which all copies will be produced...
technology's issue of pre-echoes during record play, caused by the cutting stylus unintentionally transferring some of the subsequent groove wall's impulse signal into the previous groove wall. In particular, a quiet passage followed by a loud sound often clearly revealed a faint pre-echo
Pre-echo
Pre-echo is a digital audio compression artifact where a sound is heard before it occurs . It is most noticeable in impulsive sounds from percussion instruments such as castanets or cymbals....
of the loud sound occurring 1.8 seconds ahead of time (the duration of one revolution at 33 rpm). This problem could also appear as post-echo, 1.8 seconds after a peak in volume.
Another improvement is noise reduction
Noise reduction
Noise reduction is the process of removing noise from a signal.All recording devices, both analogue or digital, have traits which make them susceptible to noise...
. The lacquer mastering method bears a higher risk of adding unwanted random noise
Noise (audio)
Noise in audio, recording, and broadcast systems refers to the residual low level sound that is heard in quiet periods of a programme....
to the recording, caused by the enclosure of small dust particles when spraying the silvering on the lacquer master, which is the necessary first step of the electroplating
Electroplating
Electroplating is a plating process in which metal ions in a solution are moved by an electric field to coat an electrode. The process uses electrical current to reduce cations of a desired material from a solution and coat a conductive object with a thin layer of the material, such as a metal...
process for reproduction of the master disc. As the DMM master disc is already made of metal (copper), this step is not required, and its faults are avoided.