Producing for Vinyl
5 December 2004
Stereo information is written into the vinyl by laying in each channel on the banks of a V shaped groove. One channel is laid in with the phase reversed. Thus in-phase signals result in the needle moving horizontally, and out-of-phase signals result in vertical movement. Stereo signals are by definition not in phase with each other (not exactly identical).
Devices like choruses, delays, vocoders or pitch shifters often create deliberately out of phase information to throw a large stereo image. Bass frequencies utilise vastly more energy to be reproduced. Large out of phase stereo bass signal can quite easily throw the stylus right out of the groove. Cutting records with this kind of signal is difficult or impossible. So Bass frequencies should be nearly or completely mono. You should not put different bass lines or kick-drums panned in opposite channels. Watch out for problematic stereo effects of all kinds. It may be pressable, but it will reduce the level that it can be pressed at.
Also watch that some of the above mentioned signal processors don't create out of phase information that when added back into mono will completely disappear ! They sound great at home, then when you spin them out on a big mono system, it disappears ! I have seen this happen, we all just sat there wondering what happened.
You can get 17 minutes on a side at LP quality. If you really don't care, you can get 23 minutes. I have a John Cage record with 30 minutes (yes, there is music on it - prepared piano). The hotter the level, the better the sound quality, the shorter the time.
At "8dB over RCA standard" you can get 13 min at 33rpm and .5 min at 45rpm. Subtract 30 seconds for every track (the space in between eats up tracks). This is nice and hot.
Bass plays better and louder at 33, high end is cleaner at 45.
High squawky noises can cause problems transferring to vinyl.
see also Acetates
see also Duplate & Mastering Berlin's helpful FAQ :
http://www.dubplates-mastering.com/faq.html
