A little more info.
While looking for more info on Direct Metal Masters, I came across the following
here:
Lacquer Master
this is an aluminium disc which has been given a laquer coating. The diameter of the Lacquer disc is always larger than the finished record. For example a 12" single or album would be on a 14" Lacquer, where as a 7" single would be cut on either a 14", 12" or 10" Lacquer. If you are making a picture or shaped disc, this must be on a 14" blank, with no test cuts. This is the master disc, it should not be played or touched. It is very fragile and the grooves can be easily damaged. The metalwork is made by a process called electroplating. Space is needed to clip on the electrode. If the master disc were the correct size, the clip would damage the grooves. Do not put cut laquers near a heat source, in a hot room, or where the sun shining through the window will heat them. If you need to store your Lacquers for a long time, keep them in the fridge. This should be no cooler than 5 degrees Centigrade. The idea is to chill, not freeze. Also make sure the box is sealed to keep out moisture and prevent condensation.
An Acetate
An Acetate is basically the same as a Lacquer, but it is the correct size. This is particularly important for 12" records, as few record players can have a 14" disc fitted on them. The main purpose of an acetate is for you to play it at home to make sure you are really happy with the cut, before you pay for the metalwork to be made. The record factory will send you one or two test pressings (TP's or white labels) before they press the rest of your records. Use the Acetate and the test pressing to compare the quality of the finished project. If they do not sound pretty much the same then there may be a problem. One word of warning, every time you play an Acetate you damage it. In the same way that you would damage a Lacquer. Try to resist playing it to your friends or in a club until you have given the test pressings the OK. (heavy stylus weights, back cueing and scratching will all ruin the Acetate very quickly). Once you have OK'd the test pressing (TP) do not play it, or the acetate, any more just in case the production run is faulty. You can use them to prove that the main run is not as good as the TP which you approved. Acetates, were also used by record companies as promotional devices for radio. They could rush an acetate over to a radio station to get air play, while the proper records were being manufactured. Recordable CD's (CDR) are almost exclusively used for this job now.
Direct To Metal
For a Direct to Metal Master a copper blank is used instead of Lacquer, the disc comes in one 14" size. DMM has several advantages. A DMM cut means you can bypass some of the stages of the metal work process. This results in the noise of the record (without music) being less; each stage of metalwork adds a little more noise The advantages of cutting DMM are, that it will handle the top end better (treble) and is more forgiving with sibilance. Also, because of the way the system works, should you need to cut long sides, a higher level can be achieved The disadvantage is, that because a DMM cut gets noisier the deeper the stylus digs into the copper, the depth of the groove is kept to a minimum. This means if you are cutting say dance music, with a lot of low bass, it is possible, on rare occasions to encounter a problem where a small percentage of finished records jump. It is not possible to get a DMM version of an acetate.
Still no insights into technical specs of the various media, but interesting nonetheless. My question would be, "Why copper?". If it's a maleability/machinability/conductivity issue, there are a thousand alloys out there that would stand-up much better.
Any thoughts?
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