DMM (Direct Metal Mastering) became popular during the 80’s but was soon less favourable as more cutting engineers went back to lacquer. It was co-developed by Neumann and Teldec, and instead of engraving the groove into a soft metal lacquer-coated aluminum disc, a DMM lathe engraves the audio signal directly onto a hard metal copper-plated master disc.
The difference between a DMM cut and a lacquer cut is that the DMM is more precise, with sharper transients and better image “edge definition,” while the lacquer cut is smoother, warmer and more pleasing on the ears.
DMM (Direct Metal Mastering) cuts always appeared to have a brighter and more defined top-end. Upon early inspection of DMM discs, this appeared to be due to a higher frequency modulation in the groove, caused by an ultra-sonic carrier tone. However there is no carrier tone on DMM cuts and the modulation is simply caused by the vibration of the cutter head.
Many critics often describe a DMM cut as too bright or too ‘edgy’. Often the reason for playing a vinyl record is to have the warm and analogue sound that is often not present in a DMM cut.
DMM did though eliminate the problem of pre-echo sometimes audible on a lacquer. Pre-echo is caused by the cutting stylus unintentionally transferring some of audio signal into the previous groove wall, causing a faint audio signal, a pre-echo.
Another argument for the use of DMM is that it removes the need for one stage of the galvanic process. Since the DMM (Direct Metal Mastering) is cut onto copper the first stage of electroplating is bypassed, resulting in cleaner processing with less surface noise and less chance of error during processing.
Although the warmer sound of lacquer could arguably be put down to the cuts not sounding as bright as DMM, the fuller sound of lacquer could be credited to the depth of the grooves on a lacquer. Lacquers can be cut much much deeper than DMM which is essential for music with a prominent low-end signal. As well as giving the fuller sound, a deeper groove is needed to avoid jumps and skips on a turntable. And even though DMM has much brighter more defined frequency response in the top end, this certainly isn’t the case with the bass frequencies, evident in most of today’s electronic music.