Mastering for Vinyl
Creating a vinyl record has been described as musical alchemy, with everything from the quality of the discs to the ambient temperature of the room affecting the overall sound of the record. The attention to detail demanded of a vinyl mastering engineer is considerable, given that even so much as breathing on a newly-cut vinyl can impact its sound quality. However, most sound connoisseurs consider a 45-rpm vinyl to be worth the trouble: the dynamic, high-resolution audio which issues from a vinyl record isn't matched by the highest-quality lossless files in digital format.
The recent resurgence of interest in 45-rpm format, as opposed to 331/3-rpm LP, is due to its unmatched, dynamic sound quality. Although sales of cassettes and then CDs overtook vinyl starting in the mid-1980s, 45rpm remains peerless in terms of its audio fidelity among other mass-produced media formats.
A knowledgeable analog mastering engineer will appreciate the need for a separate vinyl master. While some argue that one master should work for both digital and analog format, the benefits and constraints of both media are such that a CD master will not showcase the high-fidelity sound prized by discerning vinyl enthusiasts.
Analog Mastering Techniques
The easiest illustration of this audio disparity is the differing bit depths of CD and vinyl formats. While digital music is generally constrained to 16-bit audio due to the need for smaller file sizes, a 45-rpm vinyl uses 24-bit audio, requiring both a higher sample rate and a more delicate master. For example, while a digital master may be loud and heavily clipped, a vinyl master will need to reduce levels and limiting in order to make best use of the greater bit depth available.
Additionally, vinyl has its own constraints which must be worked with. It’s advisable to convert the low-end below 100Hz to mono, and to narrow the stereo width below 500Hz so as to avoid an increased phase and thinner sound upon transference to vinyl. Other considerations include more rigorous de-essing as sibilance is harsher in analog, and applying both high- and low-pass filtering to minimize potential distortion.
While a mastering engineer working in analog must consider how to optimally master for the format, it is a cutting engineer who is tasked with taking this master and translating it via the cutting lathe into a finished vinyl record. The two disciplines are complementary, but a cutting engineer will be more knowledgeable about how the physical cutting process will affect an album’s final sound, as well as what last-minute changes may need to be made to an analog master to ensure that the ensuing vinyl is perfect.
Why 45-rpm Is King
Both the 45-rpm record and 331/3-rpm LP were marketed starting in the 1940s as replacements for the older 78-rpm discs which had been in use since the late 19th century. The slower speeds, finer grooves, and improved record material in the form of widespread adoption of vinyl all led to greatly increased sound quality.
However, it is important to differentiate between the two styles of records. Typically 45-rpm has been used for singles whereas 331/3-rpm was used for longer pieces of music (hence LP). Of note is that 45-rpm is also used for longer 12” records, due to its superior audio fidelity. What distinguishes a 45-rpm vinyl record from a 331/3-rpm LP is the fact that its greater groove velocity overcomes the distorting effects of increased curvature as the playback stylus reaches the center of the record.
While curvature distortion can be minimized in LP format by keeping the grooves away from the center, this isn’t always possible depending on the length of music on the disc. For this reason, releasing music on two or more 12” 45-rpm discs, rather than a single 331/3-rpm LP, is much preferred by connoisseurs seeking the best possible audio fidelity for their music. Is it fiddly? Perhaps, but you can’t achieve your best possible sound if you cut corners!