How do I optimize the sound for vinyl pressing?
This is not as difficult as it seems, as long as we take into consideration the physical dimension of the vinyl record. All the sound information is contained in one groove per side, and it is the variations in depth and the lateral movements of the latter that reproduce the entire audible spectrum, from 20hz to 20kHz. Here you will find some fundamental elements to optimize your mixes for the vinyl record.
To better understand the particularities and the elements to which we will have to pay attention, we must first look a little at the groove itself.
The music in the groove, how does it work?
Diabolically simple & intelligent, we owe the Frenchman Charles Cros and the American Thomas Edison the idea of digging a furrow according to the vibration of the air caused by the sound. A simple point fixed on a membrane at the end of a cone, an easily engravable material, and voila!
Schematically, the groove represents the movement that the membranes of the loudspeakers must make to reproduce the music. All that's left is a playback chain and amplification (playback diamond, phono preamp and amp) so that the power of the vinyl will make your speakers vibrate and your arm hair stand on end. head feathers.
Since the phonograph ("machine that can write the voice") many improvements have come to modify the technique, and today the groove is about 50 to 80 microns deep (this is about the size of the thickness of 'a strand of hair). All the sound information is contained there, and it is its very small lateral and in-depth excursions that make it possible to “code” all the frequencies.
In the shape of a 45° V, the lateral movements represent the sum of the right and left channels (M) while the vertical movements are linked to the difference information (S). In other words, a mono signal drives the groove laterally, parallel to the record surface, while opposite phase signals drive a groove modulated up and down, perpendicular to the record surface.
The sound volume is represented by the amplitude of the excursions: the wider they are, the greater the volume. We immediately understand that un same piece will require more space on the disc if it is burned harder.
Then, each frequency is represented by its “wave”, fuller for the bass, and very short wavelength for the treble.
These physical properties have consequences that require some adaptations of your sound files!
.jpg)
The bass question
If the first recordings on disc did not contain much bass, it is not possible to make them disappear from a modern recording. That's good, vinyl is capable of reproducing deep bass.
However, they occupy a lot of space on the surface of the disc, since the amplitude of the lateral movements depends on the frequency of the signals, at constant volume. The necessary excursions will be much greater than for the higher frequencies.
On the other hand, the stereo in the bass is very difficult to burn – and to read by the reading diamond. It is important to keep them as much as possible in mono. Below 300Hz is best, and below 150Hz is essential!
Apart from this limitation, nothing special for bass management, just be aware that a (very) strong bass content will limit the available time, or the volume of the song.
And the treble?
Mids and highs are vinyl's favorite frequencies, and that's where its “warmth” comes through. There is no particular restriction in this frequency domain, apart from sibilants (see below).
When the disc is burned, many harmonics are created, and are probably the source of this impression of heat. If you recorded & mixed in the box, a gain in organicity will take place here, but beware, this will not radically transform the color of your tracks!
The phase problem
Mids and highs are vinyl's favorite frequencies, and that's where its “warmth” comes through. There is no particular restriction in this frequency domain, apart from sibilants (see below).
When the disc is burned, many harmonics are created, and are probably the source of this impression of heat. If you recorded & mixed in the box, a gain in organicity will take place here, but beware, this will not radically transform the color of your tracks!
Watch out for ssssibilantes...
Mids and highs are vinyl's favorite frequencies, and that's where its “warmth” comes through. There is no particular restriction in this frequency domain, apart from sibilants (see below).
When the disc is burned, many harmonics are created, and are probably the source of this impression of heat. If you recorded & mixed in the box, a gain in organicity will take place here, but beware, this will not radically transform the color of your tracks!
Final details
As you will have understood, the RMS level of your record will be essentially dependent on the total time of the face and the speed of rotation of the record. If you manage to respect the few constraints presented here, your disc will doubtless sound louder than if you don't, the mastering engineer having all the latitude possible to optimize the volume.
Since the disc spins faster at its periphery than at its center (yes, that's true) the same amount of music will benefit from more groove length. This is how the pieces “in your face” will be judiciously placed at the beginning of the face, while we prefer to reserve the ends of the face for calmer pieces – of the “walk” type. which will not be affected by the reduction in groove length in the center of the disc.
If you decide to entrust your mixes to a mastering studio, choose one preferably specialized in vinyl, and equipped with a burner. For the work of the mastering engineer to be optimal, it is important to reserve for him a headroom of at least 3 to 6 dB. Don't use a limiter or bus compressor to bring the peaks down to this level “artificially”, but try to mix with this objective. Of course, any necessary compression on an instrument, a voice… is to be done, but avoid using dynamic reducers on the master bus.
RunRun Records has a mastering studio dedicated to vinyl, visit this page for more information, or contact us directly.
The question of time
Time and space are relative.
No gravity theory here, but the time available on a disk depends on its size. Here you will find a summary table of the times available for your project.
It is important not to exceed these limits, at the risk of losing quality fairly quickly: it would be necessary to record less loudly (and therefore with more background noise) and with less bass.
The dynamic
Dynamics is a tricky question. The loudness war tried to answer it by annihilating it completely & vinyl is the fiercest enemy of this volume war. The radios hardly play vinyl records anymore, it becomes rather uninteresting to sound louder than its neighbor, and the dynamics can reappear! It would be a shame to make a vinyl sound like a digital file, admit that we would lose the essence of the thing. A good benchmark to respect it is la reference K12 .
Perhaps this is partly thanks to the return of vinyl as the first physical medium, but the dynamics are starting to return as well: the overall RMS level of new releases has come down a bit since 2020!
