Quirks of the format and strategies to address them
Vinyl has notable characteristics that cutting and mastering engineers need to be aware of when mastering for the format. The strategies below have all been time-tested and are even more useful for today’s diverse selection of music. However, thoughtfulness and nuance are key.
One such nuance is the relation between level and length of time. Simply put, the louder the signal, the bigger the groove…the bigger the groove, the more space is used, hence less total time can be fit on a side. Other instances of vinyl-isms deal with factors such as sibilance, low-end stereo imaging, music programming, etc. which we’ll explore in detail below.
Before you read any further, it’s important to remember as a music creator that creative freedom in the production process remains a top priority. The tips below serve as a guide and should not limit your workflow and production techniques. Depending on the music, any of these nuanced ‘vinyl-isms’ could behave differently and are best handled at the discretion of professional vinyl-cutting engineers. However, understanding them will help in all stages of production towards achieving a great sounding record.
What causes sibilance distortion?
Sibilance distortion happens when your playback cartridge can’t physically keep up with the rapid, complex modulations of severely sibilant grooves.
This is especially apparent because of vinyl’s RIAA EQ curve standard. Without going into its entire history, audio signals are cut into the vinyl master with a reduced low end and boosted highs. Consequently, turntables have an inverse EQ curve which results in flat frequency response on playback, like in the image below.
The RIAA curve allows for more music to fit on a vinyl record resulting in a longer runtime, among several other advantages. One downside, however, is that this boosted top end can also cause extremely fast, complex grooves that even the finest turntable can’t accurately trace. The result is a broken, distorted sound anytime the stylus plays over severely sibilant parts of the record.
How to avoid sibilance distortion
Vinyl mastering facilities rely on de-essers that are built for this particular problem. Several known outboard de-essers through the years include the Maselec MDS-2 and the Orban 536-A. But many vinyl cutters have been benefitting from the constant development and growing versatility of the plug-in world. Peter Hewitt-Dutton of The Bakery takes advantage of de-esser plug-ins particularly for half-speed vinyl cutting.
Real-time sibilance adjustments while the cutting lathe does its job keeps the session efficient.
Manual de-essing of a digital cutting source is also a preferred method for many vinyl cutters and mastering engineers. The RX De-ess and Spectral Repair modules each do an excellent job of isolating harsh sibilance with a transparency that’s suitably unobtrusive to the overall sound of the master. Remember though, there are many dos and don’ts of de-essing.
Listening example: before and after de-essing
Many records today have a prominent sibilant quality that lends itself well to the sound of modern day music. Pop, electronic, and hip-hop are just a few among multiple genres that are known for this sonic quality, and this can be a challenge when it comes to the vinyl format. Let’s listen to a vinyl audio recording of the song “Stardust” by Hark Madley without de-essing. Pay attention to how the sibilance translates on vinyl. Take note of the distortion in the “S” caused by the inability of the stylus to accurately trace the fast, complex grooves of the sibilance.
“Stardust” Before De-essing
Now let’s listen to the same vinyl recording of “Stardust” but with the de-essing treatment using Spectral Repair in RX. Instead of a broken, distorted sound caused by too much sibilance, there’s a much smoother quality now that we’ve tamed this high frequency energy, allowing the playback stylus of your turntable to accurately trace the grooves on the record.
“Stardust” After De-essing
Low frequency stereo imaging
Music with spatial effects that reach all the way to the low end of the frequency spectrum may potentially run into vinyl-cutting challenges. Although it’s more prone on genres such as electronic or hip-hop, even orchestral recordings can run into similar problems. When not given proper attention, you may end up with a record that’s prone to skipping.
The cause of low frequency stereo imaging
Grooves represent the mono/center information as lateral movement and the stereo/side component as vertical movement. If there’s an extreme amount of low-end stereo imaging on your music, it is more likely to produce out-of-phase information. This may cause the cutting stylus to cut with excessive vertical movements, alternating between deeper grooves and severe groove lifts. An out-of-phase low end may cause groove lifts with depths less than 1 mil (the minimum accepted depth of a modulating groove). It could even cause grooves to momentarily disappear.
This phenomenon is much less common and doesn’t occur as often as sibilance distortions. Different cutting engineers rely on purpose-built tools in varying amounts to address this, so don’t let this vinyl constraint prevent you from being creative in the production process.
How are severe groove lifts avoided?
More often than not, applying a steep high pass filter around the 20 Hz range is enough to prevent severe groove lifts from happening. But if absolutely necessary, vinyl cutting facilities rely on tools such as the low frequency crossover (LFX)—also known as EE (elliptical equalizer), “blend,” “mono-maker,” “wuss box,” etc. Simply put, it takes low-frequency stereo information and sums it to a mono signal, thus preventing excessive vertical modulations on the grooves. Before the digital revolution, LFX was built into a cutting facility’s mastering console. Nowadays, engineers have access to more digital options when mastering for vinyl.
Before the digital revolution, LFX was built into a cutting facility’s mastering console. Nowadays, engineers have access to more digital options when mastering for vinyl. Ozone Imager offers this capability. Its split-band function allows you to isolate the low end, narrowing its stereo width independently from the rest of your production This allows you to tame any unnecessary out-of-phase build-up in the low end that could compromise the quality of your music when cut into vinyl. LFX typically has crossover settings from 20 Hz all the way to 700 Hz. Setting LFX to 100 Hz is already considered excessive by many vinyl cutters. Discretion is a must!
Please take note that there needs to be absolute care when applying LFX. It can significantly alter the sound when not used properly. In fact, it’s best to leave this step in the capable hands of the vinyl experts (cutters & mastering engineers). However, it helps to be aware of this phenomenon especially if you know from the get go that you’re releasing your music on vinyl. The Vectorscope in Ozone Imager is a helpful visual aide to ensure that you’re not compromising your production with too much unnecessary out-of-phase information in the low end.
Music programming (length & track order)
Even the duration and order of songs can greatly influence your record’s sound quality. Both of these factors come into play in the inner diameter of the record, where sound quality starts to deteriorate. The farther in you are, the more brittle the highs sound. The overall sound becomes less pronounced at the top end compared to other parts of the disc.
Longer music content takes up more groove space, bringing you farther inside the disc causing the deterioration to become more noticeable. These sonic characteristics are also more apparent depending on the music. Music with a lot of energy and pronounced highs (e.g. fast upbeat songs, loud rock tracks, etc.) are more prone to these issues.
What causes sound deterioration on the innermost grooves?
Sound deterioration on the innermost grooves is caused by the slower groove speed as the stylus moves towards the center of the record. Keeping a constant revolution (either 33 ⅓ RPM or 45 RPM), the length of the groove for one revolution varies in relation to where it is on the disc. At 33 ⅓ RPMs, the outermost groove has a groove speed of 20 inches per second while the innermost diameter runs at a mere 8.3 inches per second.
This slow groove speed causes both cutting losses and tracking losses. The cutting stylus ends up having to fit much more sonic information in a shorter, smaller amount of groove space, causing more complex and rapid groove modulations. Because the playback stylus struggles to accurately trace these grooves, you end up compromising the fidelity of your top end.
How can you avoid this noticeable deterioration?
The nature of the format means you can never completely eliminate this deterioration. You can, however, lessen its impact. By keeping the running time per side at an optimal length, you can avoid the innermost diameter. Although it will ultimately depend on the musical content, keeping the length of each side of your record to 20 minutes or less would usually provide the best results. You can get away with having a longer side, especially if the musical content is dynamic and not loud throughout.
Another strategy to prevent the noticeable deterioration on the innermost diameter is by making sure that the last track on each side is less intense with a more mellow high-frequency range (e.g. a ballad, a laid-back instrumental track, acoustic song, etc.).
Optimizing the length of your music per side and keeping an eye on the optimal frequency makeup of your music is possible with tools like Tonal Balance Control. Knowing that the low end frequency range takes up significantly more room on a vinyl disc, Tonal Balance Control allows you to keep an eye on subharmonic low end build-up that could cause your music to take up more space than necessary on a vinyl record.
Addressing vinyl constraints with level reduction
Ultimately, a quick and easy way to deal with these quirks in the vinyl format is to reduce the level from the cutting master. But it comes with major caveats if not done responsibly.
Reducing the cutting level lessens the risk of sibilance distortion. Less amplitude means less stress on the playback stylus, giving it a better chance of tracing grooves more accurately and avoiding distortion. You can also avoid the undesirable characteristics of the innermost diameter. Reducing the cutting level decreases the overall groove width, requiring less space to cut, thus avoiding the inner surface of your record. You also reap the same benefits when dealing with music that has a lot of low-end vertical information. There’s less risk of severe groove lifts when cutting your vinyl master at a lower level, or in a similar vein, applying a steep high pass filter at the low end to lessen the cutting level of the bass frequencies.
Despite all these advantages, significantly lowering the cutting level can potentially bring down your record’s signal-to-noise ratio to unacceptable levels. The surface noise could increase dramatically, therefore compromising the overall fidelity of your music.
