Excerpted from our new guide The Musician’s Guide To Vinyl, this post digs into post-production audio mastering for vinyl records.
Mastering is the final step in the recording process, which takes place after the mixing process (post-production) to optimize and add the final sonic touches to your recordings. When you send your master to a professional mastering studio like The SoundLab at Disc Makers for audio mastering for vinyl records, your overall program level is set, as well as the song-to-song (AKA relative) levels.
EQ, compression, and other digital processing is also used to make your recorded material sound as good as possible when played in the various listening environments of the customers who buy the end product. When that end product is a vinyl record, certain specific considerations (many already mentioned) need to be accounted for.
Sibilance and bass
If the music program is sibilant overall, the audio can be cut at a lower amplitude, which can help with the distortion caused by the high frequency information. The result, though, is a vinyl record that’s at a lower level, and the surface noise will be more prominent – not to mention, it’s not going to be comparable to other vinyl albums. Just like CDs, you’ll want to compare your vinyl album to others in your genre. The more compromises you make compressing your program or lowering amplitude to compensate for anomalies in the mix, the more you’ll notice a difference when compared to other vinyl releases in your genre.
Sibilance issues with a vocalist can be addressed, to some degree, in mastering, though it poses challenges. By the time a project reaches the mastering stage, the vocals are mixed among various other instruments and sounds, making it difficult (or impossible) to pick out the vocals exclusively. De-essing in the mixing stage can be very important for vocals when pressing for vinyl, particularly with a vocalist who’s prone to sibilance. Microphone selection and a good pop filter can also go a long way toward avoiding these issues.
Just like with sibilance, proper handling of your bass frequencies is best done in the mix. There are things that can be tackled in the mastering process: one approach is to take everything below 100 Hz and center it. This process and standard of centering bass frequencies can be listed among the major differences between audio mastering for CD and other digital formats versus audio mastering for vinyl.
Program order and inner groove distortion
Inner groove distortion refers to how tracks closer to the label and spindle hole on a record can sound audibly different that those on the outer edges. (This is an issue that can be affected by the quality of a turntable and needle on a listener’s record player.)
A record is spinning at a fixed speed: it takes the needle the same amount of time to travel from point A back to A in one rotation, whether it’s on an outside groove or the closest groove to the spindle hole. At the beginning of the LP, on those outer grooves, the signal is cut across a relatively long section of vinyl. And just as with analog tape, the longer a signal is spread out across the medium, the higher the quality.
When you get to those shorter grooves near the spindle hole, your signal is transferred to a much shorter section – the same amount of audio information is recorded onto that shorter segment. The audio information, in the form of ridges and valleys, is closer together, and the more dramatic curve of the groove can affect the needle’s ability to track and read the information accurately.
Let’s continue with the tape speed analogy
Consider the outer grooves as equivalent to 30 inches-per-second of analog tape (more or less), and the inner grooves more like 7/12 inches-per-second. To avoid issues stemming from the limitations of those inner tracks, the recommendation for any vinyl project is to keep your louder, bass-heavy tracks at the front end of either side, and your softer, less dynamic tracks for the end of the programs.
This could represent a notable difference in the programs between your CD and vinyl LP release, if you are doing both. With a CD, you can arrange songs purely for continuity and pacing, while with vinyl, factors such as song length and dynamic content may change the order of your songs and which songs appear on one side or the other.
Get more information on recording, mastering, and preparing your release on vinyl in our new guide, The Musician’s Guide To Vinyl: Everything you need to know know about how to make a record.
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