DMM technology and manufacturing process
Direct Metal Mastering (DMM) is the name of a process used in the manufacturing of analog fine-grooved records. The DMM technique was developed as a better alternative to the traditional process of preparing matrices used for vinyl record pressing.
In the traditional vinyl record manufacturing process, during the first stage, a lacquer disc is cut which is used for making more metal copies. Subsequent generations are called the “father” (negative), the “mother” (positive), and at the end we have matrices (negative) used directly for record pressing.
In the Direct Metal Mastering technique, the whole process is shortened. A properly adjusted head cuts a groove in a copper disc. The copper disc plays the role of the mother and is used for making manufacturing matrices. Cutting in copper helps to reduce noise and improve the precision of transferring information at higher frequencies, and to reduce mutual reactions of neighbouring grooves.
Once a matrix is made, on the next stage a mixture is prepared. Matrices are placed in a press and the groove pattern is pressed in a heated mixture. Before a piece of material is entered and pressed with the matrix, a label with description is pressed into the centre of the record. Records pressed in this way are immediately cooled down and sent to the final manufacturing stage where excess material is trimmed. A record is cooled down