Half-Speed Mastering Explained
Miles Showel of Abbey Road Studios.
Vinyl is making a comeback, and so is the process known as half-speed mastering. Bobby Owsinski states that “This is where the playback speed of the tape and disk cutting lathe are slowed down by half to cut the lacquer master in order to improve the sound quality. This unusual process disappeared for quite a long time, but is being revived again at Abbey Road.” Miles Showel of Abbey Road Studios is one of the mastering engineers reviving this mastering technique.
If you’re unfamiliar how vinyl records are made, a lacquer disc is engraved using a cutting lathe, which is used to create a master stamp. This master stamp can be used to produce about 100,000 vinyl records. Polyvinyl chloride pellets are melted down into a biscuit shaped puck that is pressed using the master stamp. The final product is what you would recognize as a vinyl record.
The “half-speed” part of this process occurs while the lacquer disc is getting engraved. By slowing down the cutting process, less stress is placed on the lathe. Showel mentions that there’s less heat that gets generated and that the lathe has an easier time accurately cutting high-frequency content. A 10,000 Hz wave getting cut in real-time would require the lathe to oscillate 10,000 times per second. When getting cut at half-speed, a 10,000 Hz wave would require the lathe to only oscillate 5,000 times per second.
Showel says that there’s a noticeable difference in quality between records cut at half-speed and records cut in real-time. Based on his explanation, it appears as though this difference is only noticeable on mid to high-quality record players. Still, it’s interesting that this technique is being used once again to achieve records of enhanced quality. You can learn more about half-speed mastering via Bobby Owsinski’s blog, and by watching UMC’s video featuring Showel.
Charles Hoffman is a Mixing and Mastering Engineer at Black Ghost Audio. After graduating from the University of Manitoba with an English degree, Charles completed his education at Icon Collective in Los Angeles, CA.
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