Motor position

[davecooper]

Nanook, can you explain a bit more? I would be interested in the source of these lateral vibrations and how these have a different effect depending on motor position. Is it a case that 7 7:30 is optimum but 9 o clock would be better than 11 etc?

[Jacques Merde]

Nanook,

I have to admit to having not given that much thought. My initial reaction is that it would be a bigger issue for some design directions than for others. For example, a light suspended subchassis design might be particularly sensitive. Noisy motors, like the commonly available steppers and (most) PMBDC types would also be prone to issues.

Doesn't seem like it would be too hard to take some meaningful measurements, though. Hmmm...

[Nanook]

if assuming that the vibrations are random and distributed evenly.

if at the "11 o'clock" position, any vibration will almost always create a much larger vibration (based on vector analysis) in the lateral direction (where it the cantilever and arm can very easily be moved) compared to the dorsal direction (in-line to the tonearm), assuming the arm pivot is firmly located.

If at the "7:00 o'clock" position , assuming the pivot is firmly mounted, then the dorsal movement will be very minimal as the angle will be much smaller, therefore the magnitude of the vibration acting on the cantilever will be reduced.

to me it seems intuitive. Someplace I did all the math, but lost it all in "the crash of summer 2010"