THE VINYL MASTERING
Written by Fred Woff - sound engineer - www.fredwoff.com
I - PLACEMENT OF TRACKS ON THE RECORD:
Place the most dynamic, strongest, and most "loaded" tracks at the beginning of the side rather than at the end of the side. Indeed, it is important to take into account the fact that the sound quality of the vinyl progressively diminishes as the groove approaches the center of the disc.
Why does the quality decrease as the groove approaches the center of the disc?
A record spins at a constant speed, regardless of which part of the disc the needle reads (33 1/3 revolutions per minute). However, due to the spiral engraving, the circumference of the grooves decreases as the spiral unfolds towards the center. The length of one revolution (one turn = circumference) of a 33rpm record is 93 cm at the beginning but only 38 cm at the very end! Therefore, the scrolling speed of the material at the tip varies by a ratio of about 3 to 1, that is to say, from 93 cm / second at the beginning of the side, down to 38 cm / s. at the end of the side. Sound quality is therefore reduced by approximately 3 times at the very end of the side. This is what we call audio losses. They are anything but negligible (see paragraph below).
II - SIDE LENGTHS:
There are several rules to consider:
1°) The longer a side is, the more the recording sound level must be reduced (thus increasing the risk of perceiving the natural background noise of the vinyl).
2°) Low frequencies take up more space on the disc than high frequencies. Masters with an excessive presence of low frequencies are prohibited (grooves too wide). The opposite is also prohibited (grooves too narrow).
3°) It is necessary to distribute your tracks well according to their duration, and avoid, for example, putting 12 minutes on side A and 24 minutes on side B. The more intelligently the durations are distributed, the more homogeneous the quality will be from one side to the other. The engraving level is determined by the longest side.
Here are the expected times per side for a nominal level (0 dB) engraving, considering that the mastering has been done according to the rules of the art (adequate dynamic ranges, among others):
Rock, Reggae, Classical, Pop, etc. music:
12’’ - 33 rpm: 19 min
12’’ - 45 rpm (maxi 45t): 12 min
Electronic music such as Rap, Electro, etc.:
12’’ - 33 rpm: 16 min
12’’ - 45 rpm (maxi 45t): 10 min
Music with a "loaded" spectrum like Techno, Metal, Noise, etc.:
12’’ - 33 rpm: 14 min
12’’ - 45 rpm (maxi 45t): 8 min
It is possible to "push" the side lengths reasonably up to 21 minutes or even a little more, but at the expense of significant level losses during engraving. Each additional minute beyond 19 minutes results in a decrease in the engraving level and an increased perception of background noise and crackling...which is not desirable.
Each additional minute counts and reduces the sound quality. As an indication, between a 15-minute side and a 22:30-minute side mastered according to the rules of the art, the background noise is perceived as 50% more present when listening. This is inherent to the old analog technology of vinyl, which has its advantages but also its disadvantages, which must be taken into account.
III - CLIPPING:
Clipping is an undesirable form of digital saturation.
The peak level of a digital file, in practice, cannot exceed 0 dB. This is the maximum achievable level. If, during the export of your files on your creation software, the sound were to momentarily exceed the 0 dB level, this would create what is called clipping, which you can see in the illustration below.
The presence of clipping on a mixing or master file is obviously to be avoided, as this will cause the digital-to-analog converters to CLIP in turn when your file is played during engraving. This distortion will inevitably be transferred to the vinyl.
On the left: clipped mastering, too compressed, low dynamic range: it's difficult to engrave as it is (or at a very low level, and/or with distortion).
On the right: mastering with a good dynamic range without clipping
IV - DYNAMIC RANGE:
The "LU" decibel is the current representative unit of the average dynamic range of a piece of music. The average dynamic range expected for a vinyl master is ideally 13 dB, and remains acceptable between 10 and 14 dB LU. Most well-done mixes have a dynamic range often between 11 and 16 dB LU.
It is during mastering that choices should be made in this regard. For reasons that would be lengthy to discuss here, many mastering engineers provide masters with a very reduced dynamic range, incompatible with vinyl engraving. Beware! A mastering of this type is most often unusable for vinyl, or at the cost of a greatly reduced quality and numerous artifacts in the sound.
Make sure from the start that your engineer is capable of mastering an album without practically using any dynamic compression. This is very important for vinyl records. Ask them before making an appointment.
Why should we avoid overly compressed masterings?
Reducing the dynamic range has so far allowed to virtually increase the sound level on digital media, some producers and musicians thinking that the louder and more competitive the sound, the higher the sales could be. However, this "commercial" reasoning makes no sense! On the contrary, it has been widely proven since then that this type of master generates only listening fatigue (which makes you want to cut the sound!) and also, a master overly compressed in dynamic range is burdened – even in digital - with significant sound distortion as well as a drastic reduction of the vitality of the sound (soft, flat sound). Today this practice is considered aberrant, but habits are hard to break, and the vast majority of sound engineers still practice these "competitive" masterings, which we strongly discourage.
The advantage is obvious: by using software or devices, it is possible in a very short time and with very little knowledge to achieve this type of mastering by crushing everything that exceeds automatically! It's easy, sometimes lucrative for some, but this type of mastering absolutely does not "work" for vinyl, nor for sound lovers!!!
It should be understood that the more the dynamic range is reduced, the higher the distortion rate increases in engraving as well as in reproduction! Below 10 dB LU and up to about 8 dB LU of dynamic range, the engraving can be done but the result will be disappointing to the ear (see photo and explanations below).
Below 7 dB LU, the engraving machine will force, heat up very strongly and eventually trip if a nominal level engraving is imposed. It is therefore necessary to counteract this problem by manually lowering the engraving level on the machine. As a result, it will be necessary when playing back the record to increase the volume of the amplifier, which will also have the effect of significantly increasing the background noise of the vinyl (hissing, crackling).
Distortion will also become very audible, even intolerable in the most extreme cases. This creates a kind of "mushy sound soup" that is soft, saturated, and undefined. We therefore advise you to avoid clipped masters as much as possible. This is a harmful practice, and it will seriously damage the sound on vinyl, or even prevent any possibility of engraving. So back to the sender, back to square one!
The best solution is once again to call upon a mastering engineer specialized in vinyl to ensure the best possible rendering, the best possible engraving level, with the lowest possible distortion. In a few words, the purest sound that enhances your music.
A vinyl mastering specialist will always offer you masters with a wide dynamic range that will honor your music on vinyl media as well as on other media. The war of levels is over today even in digital, as streaming platforms have an automatic regulation system that penalizes overly compressed masters! Make your choices accordingly and choose your mastering engineer wisely.
Left image: Master with typically over-compressed audio content
Right image: result on vinyl. The grooves touch or even cross each other, there is over-modulation. Consequence at the sound level: strong clipping (high saturation), crosstalk (poor stereo channel separation), pre and post-echoes, groove jumps.
V - THE EXTREMES OF THE AUDIO SPECTRUM: SUB-BASS AND EXTREME-HIGHS:
● An excessive proportion of extreme frequencies in a mix and a master can indeed be harmful, as is well known and true. More specifically, it should be understood that too high a proportion of low frequencies implies a reduced duration of the record, or a significant decrease in the engraving level. In the case of short duration, too much bass also has the consequence of increasing harmonic distortion, and in really abusive cases, generating stylus movements so significant that the risk of groove jumps must be taken very seriously. As for high frequencies, abuse in this frequency range simply leads to distortion. A typical example among many others: the sibilants of voices, the "S," are transformed into "CH". Too much high-frequency content can even generate overheating of the engraving head, and thus prevent the engraving from being carried out in its entirety. In such a case, it is the machine's safety system that abruptly interrupts the engraving to avoid destroying the precious head (which costs a small fortune).
● To avoid all these spectral imbalances, the general rule is simply to use common sense and to avoid any abuse of these extreme frequencies during mixing. Just avoid over-boosting the sub-bass, especially if you are not working in a studio created and validated by an acoustician (very significant risks of perception errors in the lower end of the spectrum), and if you do not have large-diameter speakers during mixing (which allow you to correctly perceive these frequencies). Similarly, avoid excessively accentuating the ultra-high frequencies, which are most often found in cymbals, tambourines, shakers, voice sibilants, and some analog synthesizer filters pushed to their limits.
● But for all that, if we warn you against abuse, do not fall into the opposite extreme, namely overdoing caution, which would be just as harmful to your sound. Particularly by lowering the bass too much, especially through some radical filtering practices that are not always appropriate. Using, for example, a low-cut filter during mastering - as is often advised on the internet - is not necessarily a guaranteed solution for a good engraving. It is a preventive method that is often a bit too simplistic, a bit too coarse, which can sometimes solve some problems, but which can also harm your sound. Only a qualified engineer will know how to make the right decision regarding this. They will use the appropriate filters and often opt for more precise and less invasive tactics.
CONCLUSION: It is better not to improvise in this kind of sound choice and manipulation related to mastering. It is your record at stake. Trust only experts who know their trade perfectly if you want an optimal result. Only experienced mastering engineers will know how to frame and optimize your bass and treble with a hundred times more precision. And as for mixing, it's simple: mix in a good studio, take regular breaks, mix naturally, as your music should sound to your ears. Just don't abuse the extreme frequencies like it's bad to abuse fat or salt for your health! Then let the mastering engineer (preferably a vinyl specialist) manage the final balance with their degree of precision that you cannot achieve without experience, tools, and the appropriate place.
VI - STEREOPHONY IN MIXING: What not to do! :
● In mixing, never try to create artificial stereophony from a mono track distributed on the L / R channels by inverting the phase of one of the two channels. This practice has been strictly prohibited since the beginning of stereophony until today,
● Avoid mixes including excessive stereophonic effects. Panoramic views of mono sources are not a problem as long as they are never oriented 100% on a single channel, especially if the instrument has low frequencies. On the other hand, excessive enlargements of genuinely stereophonic sources can be problematic. Phase effects or pseudo "3D" effects on your mix tracks can cause major problems in engraving if they are excessive. Control by listening to your mix in mono. If you notice too much attenuation, reduce the intensity of your effects. Or impose a pan of at least 6 dB difference on one of the channels of your effect.
● Avoid bass drums or basses on the left or right. If this is the case for some records from the 60s, such as those of the Beatles, it is not a deliberate choice on the part of the artists, but rather a technical non-choice due to the fact that the EMI consoles of the time were simply not equipped with a pan potentiometer, but with routing switches! Recordings were made on 4 mono tracks, and the only solution to create a pseudo-stereophony was to distribute the 4 channels, either on the left, center, or right. Note that these pseudo-stereo mixes have never been approved by the artists. They were often made without the presence of the artists, and hastily. At the time, stereophony was not common. The standard was mono! It should be known that proceeding in this way to create these records required engravers to engrave at a particularly lower level than normal. And the drop in level consequently resulted in an increase in the background noise of the vinyl. If you proceed in the same way in your mixes, in order to find this "vintage" effect, you are warned of what might happen to you!!
● Take care of your sound recordings, especially the bass drum. A poorly placed microphone can lead to excessive signal asymmetries that will cause problems in mastering and/or engraving. The same goes for overheads of drums, which, if not centered properly in relation to the bass drum, may cause phase anomalies between the left and right channels for the bass drums.
● Absolutely avoid 100% left and right panning of multi-microphone recordings of electric guitar amps (the "wall of sound" effect). Check your mix in mono to see if the attenuation of the guitars is not too significant. If it is, then reduce the stereo width while compensating for the level, until the difference in level between mono and stereo is tolerable to the ear. Note that there will always be a difference in level, and this will create differences in timbres (discolorations). It's a matter of finding a compromise. Possibly create a specific mix for vinyl. Also understand that if the attenuations and timbre differences are too strong, it means the recording is simply haphazard and inadequate. In the worst case, try adding a delay effect of a few milliseconds to one of the channels and then see if the attenuation in mono mix control is less significant. Make sure your microphones are strictly equidistant from the speaker or each speaker. This is the primary source of problems!
● Do not fall into the paranoid trap of fearing stereo ! Any extreme opposite tendency to want to "tighten" the mix towards mono is just as unhealthy as abusing the width of the stereo field! Vinyl does not like extremes. Neither too much nor too little. Mix normally, simply avoid drastic choices and all the extremes explained earlier.
VII - SIBILANTS:
● Sibilants are sounds produced by the pronunciation of the consonants "S", "Z". Although the term is not quite accurate in terms of linguistics, it also includes, in the field of sound engineering, the consonants "T", "J", "CH", "F", "V", as well as the English "TH" and the Czech "Ř".
● When recording voices with a microphone relatively close to the mouth, these sibilants often reach an excessive sound level, and the use of dynamic compressors only increases them further, as most of them are not or little sensitive to the high part of the audible spectrum.
● It is therefore imperative to use a de-esser on each vocal track during mixing to compensate for these problems.
● For the settings, do not de-ess too much (muffled "S" sounds) or too little (aggressive "S" sounds). De-ess just enough so that it sounds good to your ears. Non-de-essed vocals = distorted sibilants on vinyl (in such cases, the "S" turns into "CH", or even "F", which is not the most beautiful effect...).
● Be aware that styluses with poor quality diamonds naturally tend to distort the reproduction of sibilants. Therefore, when you listen to your test press or your vinyl records, it is imperative to listen to them with a properly adjusted vinyl player, equipped with a high-quality head and diamond for optimal tracking (a diamond capable of faithfully reproducing the finest curves engraved on the groove). This is often not the case for diamonds sold in stores for around 20-30 €... Prefer elliptical, super-elliptical or even more refined diamonds over round or cylindrical ones, which are inexpensive but have poor sound reproduction. If the diamond has no brand or information about how it is cut, it is actually a low-end synthetic sapphire, with a shorter lifespan and often distorted sound reproduction, which can also potentially wear out your records quickly. If you have requirements in terms of sound quality for cutting, be consistent with your requirements by being well-equipped at home, starting with the quality of the diamond on your vinyl player. This is actually the essential element, far too often neglected.
Fred Woff, © 2019. All rights reserved. Any reproduction, even partial, is prohibited without the express authorization of the author.