Half speed master

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.

My understanding is that half-speed mastering was used to cut discrete 4 channel disc in the early 70s. It was developed so they could accurately cut 40kHz+ signals to the vinyl. It was thought that when used on normal stereo recordings that greater fidelity would be achieved, but there is some controversy over that claim. As a process it has stood the test of time, but in and of itself half-speed mastering doesn't guarantee better quality anymore than any other "remastered" claim.

Half-speed mastering is done to move the resonant frequency of the cutterhead up one octave. This makes it a lot easier to deal with. Decca developed this technique in the 1950s; many Londons and Deccas are 1/2 speed mastered.

The first answer was the right one:

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.