The audio transfer on vinyl disc requires different mastering steps compared to a CD master or for digital distribution.
To obtain the best results it is therefore necessary to perform a specific mastering for vinyl, strictly following a few but important indications.
To prevent low frequency counterphases in stereo recordings, which due to the discontinuity of the groove could lead to needle skipping, it is advisable to record bass below 150 Hz in mono.
Eliminate frequencies below 40 Hz as they can generate resonance in the turntable arm and cause the needle to skip.
Too accentuated low frequencies would lead to the needle skipping, therefore requiring the reduction of the recording volume with consequent reduction of the audio quality.
A physical limit of the stereo groove prevents the cartridge from correctly interpreting frequencies that are too high, especially for those equipped with a spherical stylus.
If there are very exalted high frequencies in the master, we will be forced to limit them, thus reducing the possibility of distortions occurring.
Keep in mind that:
- It is not possible to record frequencies above 14/15 Khz at very high volumes
- Long notes cannot be recorded at high frequencies
- If possible, avoid normalizing the finished tracks, preferring to carry out this process on single tracks or even on single sounds, especially if these have been sampled from CDs or vinyls.
- It is advisable to provide a playlist in which the tracks with higher frequencies are at the beginning of the disc side, especially for 33 rpm vinyls. At the end of the disc side the tracks could be less open.
VOICES AND HIGH FREQUENCIES
Unlike the reading needle which have a rounded shape, the engraving ones are square and this geometric difference causes a mismatch between the needle and the groove.
Due to this difference in geometry, some sounds (often voices) especially at high frequency may be different from the master audio, especially at high volumes.
The rounded tips in certain conditions (such as those mentioned above) could cause a kind of hopping perceived by the ear as a distortion. The spherical points, due to a lower adherence to the groove, they only partially reproduce the signal contained in it. The elliptical points allow a better reproduction of the signals contained in the groove.
To avoid the occurrence of the above problems, a good mixing is essential, accompanied by careful listening, with a linear system and possibly at a high volume.
VOLUME OF THE ENGRAVING
The volume of the recording is inversely proportional to the amount of music to be recorded on each side.
Basically, the shorter the duration, the wider the grooves and the higher the volume, vice versa a longer duration will correspond to narrower grooves and lower volume.
It is important to understand that a longer duration determines a lower volume which in turn determines a degradation of the signal / noise ratio, in even simpler words, the longer the duration and the worse the sound quality.
For greater clarity, the duration / volume / quality ratio can be summarized as follows:
DISC 12 "AT 33 SPINS
up to 15 MINUTES -> High volume -> Max quality
15-20 minutes -> Medium volume -> High quality
20-25 minutes -> Low volume -> Good quality but more background noise
DISC 12 "AT 45 SPINS
up to 11 MINUTES -> High volume -> Max quality
11-15 minutes -> Medium volume -> High quality
7 "DISC AT 45 SPINS
up to 4 MINUTES -> High volume -> Max quality
4-5 minutes -> Medium volume -> High quality
5-6 minutes -> Low volume -> Good quality but more background noise
HOW TO SEND THE MASTER:
- Max volume: - 12 dB rms (compressed audio close to 0 dB can be transcribed, but will suffer a reduction of the maximum possible level and the maximum time available per side)
- Avoid, if possible, the use of psychoacoustic enhanchers and brickwall compressions, i.e. leaving a certain dynamics / headroom
- Send audio files in .wav format (24 bit recommended)
- Create a file for each side (e.g. one file for side A and one file for side B), taking care to insert the songs in the right order and to set the desired pauses between one song and another
- Provide a text file with the track list of the songs and for each the start time, the end time, the duration of the pause (see example below)
Track 1 00:00:00 03:55:12
Break 03:55:12 03:57:12
Track 2 03:57:12 07:03:18
Break 07:03:18 07:06:18
Track 3 07:06:18 11:42:22
Break 11:42:22 11:44:72
Track 4 11:44:72 14:41:57
- Use 2-track 1/4-inch coils
- Send a reel for each side (e.g. a reel for side A and a reel for side B), taking care to insert the songs in the right order and to set the desired pauses between one song and another.
- Provide a text file with the track list of the songs and for each the start time, the end time, the duration of the pause (see previous example, see online master submission)
- Maximum recording speed: 38 cm / sec
- At the start of the reel tape insert the reference tones lasting at least 30 seconds at frequencies of 100 - 1,000 - 10,000 Hz smoothed to -10 db.
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