Most people want their records LOUD. A brief explanation of what happens when cutting a record may be in order. The recorded groove is a spiral starting from the edge, going to the center. It's very shallow, and is required to be deep enough for the needle to stay in it. The sound is recorded by vibrating the cutting needle which causes the groove to move from side to side in a mono recording, and somewhat up and down as well in a stereo recording.
The more time recorded on the record, the more revolutions the record turns, making for a longer groove, and hence a thinner - shallower groove.
With computerized pitch, the grooves are placed right next to each other when there is little or no volume. Since the louder recordings require more vibrations, the needle deflects sideways, and possibly into the adjacent groove causing a skip. To prevent the grooves from colliding, the computer adjusts the spacing between the grooves to make sure they do not collide and cause the record to skip.
Therefore, if the recording is long, the grooves are shallower. If the recording levels are louder, there must be more space between them. I don't like to cut less than a .0025" inch groove. This is about the limit for assured tracking.
The RIAA and NAB have set forth specific physical groove vibrations to be determined as "Standard Reference Level". All mastering rooms calibrate their equipment to this level through test equipment and test recordings. Most records are cut at the following levels:
12 or 10" 33 rpm: Standard Reference Level or 0db.
7" 45rpm: +3db over Standard Reference Level.
7" 33rpm: -3db under Standard Reference Level.
The slower RPM and smaller diameter of the 7" 33rpm record causes a slower movement of the needle through the grooves, and therefore a higher risk of distortion. It is wise to cut the 7" 33-1/3 at this lower level even when the sides are short.
After much plugging away at the computer, I have come up with the following recommendations for the maximum time for different formats of records. These max times are based on relatively normal master tapes, and not cutting less than .0025" grooves:
12" at 33 rpm, max time at 0db, 20 mins.
12" at 33 rpm, max time at -3db, 24 mins.
12" at 33 rpm, max time at -6db, 28 mins.
7" at 45 rpm, max time at +3db, 4 mins.
7" at 45 rpm, max time at 0db, 5 mins.
7" at 45 rpm, max time at -3db, 6 mins.
7" at 33 rpm, max time at 0db, 6-1/2 mins. Not Suggested due to distortion potential.
7" at 33 rpm, max time at -3db, 7-1/2 mins.
7" at 33 rpm, max time at -6db, 9-1/2 mins.
If you have a 5 minute side you want cut on a 7", you can cut it at either 33 or 45. You'll notice that even though the level for such a length at 45 is less than normal for a 45, it is still louder than cutting it at 33 without distorting. Click here to get a more detailed explanation of cutting 7" records. I would even suggest cutting a 6 minute side at 45 even though the levels would be the same. The faster speed would make for a cleaner sound.
Dance club music is usually requested to be cut LOUD, even if distortion occurs. I cut dance music at 6db over standard reference level. The grooves must be deep (about .004") to keep the stylus from jumping out and skipping when cutting at these levels. Therefore, the maximum times per side are as follows:
12" at 33 rpm, max time at +6db, 12:30
12" at 45 rpm, max time at +6db, 9:15
10" at 33 rpm, max time at +6db, 9:45
10" at 45 rpm, max time at +6db, 7:15
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