Not all lathes can operate at 16rpm. Certainly speed stability is a much greater issue at the lower speed!
I don't buy the 40Hz thing. Our cutter seems to go down much lower than just 20Hz, as do our electronics.
Seems to me it was Decca in the UK that first started using 1/2 speed mastering as part of their method of controlling cutterhead resonance. Essentially, this put the resonance in the upper part of the last octave, which is beneficial due to the RIAA pre-emphasis (boost at high frequencies); IOW it meant that less amplifier power was needed.
There are indeed tradeoffs!
I don't buy the 40Hz thing. Our cutter seems to go down much lower than just 20Hz, as do our electronics.
Seems to me it was Decca in the UK that first started using 1/2 speed mastering as part of their method of controlling cutterhead resonance. Essentially, this put the resonance in the upper part of the last octave, which is beneficial due to the RIAA pre-emphasis (boost at high frequencies); IOW it meant that less amplifier power was needed.
There are indeed tradeoffs!