Great thread and nice responses!
A quick clarification of the stylus motion in a grove: The left/right signal is encoded in +-45 angle plane. Vertical or horizontal motion are additions/subtractions of L and R signal. A good picture of cutting motion is found here:
Stereo disc recording
Therefore vertical or horizontal motion alone do not contain any "stereo" information. Only the combination does. Stated correctly the +45 degree plane contains one channel and -45 degree plane contains the other. Also, check out wikipedia's description:
Also, its a good exercise to look at a cartridge. The cartridge coils reflect the encoding in the 45 degree plane as well
Sketch of stereo cartridge
I hope this helps picturing vinyl cutting and playback somewhat.
Enjoy!
Rene
A quick clarification of the stylus motion in a grove: The left/right signal is encoded in +-45 angle plane. Vertical or horizontal motion are additions/subtractions of L and R signal. A good picture of cutting motion is found here:
Stereo disc recording
Therefore vertical or horizontal motion alone do not contain any "stereo" information. Only the combination does. Stated correctly the +45 degree plane contains one channel and -45 degree plane contains the other. Also, check out wikipedia's description:
In the Westrex system, each channel drives the cutting head at a 45 degree angle to the vertical. During playback the combined signal is sensed by a left channel coil mounted diagonally opposite the inner side of the groove, and a right channel coil mounted diagonally opposite the outer side of the groove.
It is helpful to think of the combined stylus motion in terms of the vector sum and difference of the two stereo channels. Effectively, all horizontal stylus motion conveys the L+R sum signal, and vertical stylus motion carries the L-R difference.
Also, its a good exercise to look at a cartridge. The cartridge coils reflect the encoding in the 45 degree plane as well
Sketch of stereo cartridge
I hope this helps picturing vinyl cutting and playback somewhat.
Enjoy!
Rene