Half speed master

Half-speed" mastering refers to slowing the cutting lathe to half-speed while cutting the album stamper. This resulted in a more accurate and deeply etched groove that improved bass response and produced more dynamic sonics.

Here is a link to more info:

http://www.audioinvest.no/tt_vinyl/suprdisc/omr_sd.htm

I believe that the primary advantage to 1/2 speed mastering is to make it easier to accurately cut HIGH frequency modulations. If the cutter is suppose to be cutting an 18,000 Hz signal, at half speed it is cutting only a 9,000 Hz signal.

It seems if you read this from the link I provided...

MFSL's exclusive "half-speed mastering" also allows us to use only one-fourth the power that real time cutting takes. So we never have to push our cutting head amplifiers to their limits. This gives us much more head room for far superior dynamic range, top-end and overall frequency response, along with better stereo separation. And we don't use transformers or employ limiting in our cutting process."

...that we are both correct.

Thanks for the great explanation.