advantages? of higher speeds

[cuttercollector]

What , if any, are the theoretical and practical advantages (or disadvantages) of higher speed cutting and playback?
This is from another thread talking about using half speed mastering to extend the effective frequency response and level of a home disc cutting unit.
I had always thought that gains in maximum level and dynamic range as well as frequency response were to be gained at higher media speeds
(45 or 78 vs. 33 1/3). Now some are saying, no, the cutter has a maximum frequency limit and a maximum level no matter what speed.
Without adding in other issues like the inability of 3 mil 78 styli to trace high frequency information in a more crammed space at lower speeds or adding half speed mastering into the picture, what if anything is to be gained on the cutting side, or complete cut/play cycle with current stylus shapes, modern professional cutters and playback cartridges etc. from higher speeds?

[cd4cutter]

CC, the whole issue of increased media linear speed is much the same for analog disc recording as it is for analog tape recording. It is mostly the matter of making the recorded wavelength sufficiently long even at the highest desired signal frequencies that it can be accurately scanned by the playback stylus (in the case of records) with minimal tracing distortion. In the case of recorded tape, the width of the gap in the playback head functions in much the same way - when the gap width approaches the recorded wavelength (or more accurately half the recorded wavelength), the output signal is markedly reduced - it's "scanning loss" for tape (actually called "gap loss"). (See the other thread here on scanning loss.) There is little or no effect or contribution of the recording stylus or cutter head on this improvement. The only other effect is the nature or spectrum of the surface noise which tends to move up in frequency with increased linear groove speed.

So you will note that the use of a 0.7 mil playback stylus for 33-1/3 rpm records results in better performance (less scanning loss) than the use of a 3.0 mil stylus when operated at 78rpm at the same diameters. The ratio of 3 to .7 mil is 4.29 while the ratio of the wavelengths at the same frequency is 2.34 between 78 and 33 rpm. So the typical LP will produce significantly less scanning loss and tracing distortion with a .7 mil stylus than will the equivalent 78rpm record at the same diameter when played with a 3 mil stylus. However, if you were to play a good vinyl 78 with a .7 mil stylus you'd get WAAAYYY less scanning loss than with either of the other two configurations. Hint: How to make the highest fi? Cut at 78rpm and play with a microgroove stylus.