Choose the resolution in Logic Pro X

Francis

Francis

Composer ⎜ Sound Engineer ⎜ Sound Designer

 

I received an email asking me how to choose the resolution in Logic Pro X.

16 or 24 bit resolution?

Before recording your guitar or voice in Logic, you can choose in the Preferences menu, Recording what is called the recording resolution. I already talked in a previous article about Logic’s audio recording formats.

Preference Recording

Most sound cards offer 16 or 24-bit resolution and sampling rates up to 192 kHz. Below is the yellow resolution of my Universal Audio Apollo 16 card.

apollo 16 Resolution

If your sound card only offers 16 bits / 44.1 kHz. For example, you will not be able to choose another resolution in your sequencer. Because Logic Pro X will determine the resolution of your sound card!

Why record with 24-bit resolution?

We know that a CD is in 16-bit / 44.1 kHz format. So why choose to record with a 24-bit resolution?

Simply because it offers you a wider dynamic range. Thanks to this wider dynamic range, this allows you to record less close to 0 dB. The 0 dB being a value not to be exceeded in digital under the risk of non-musical saturation.

To better understand….

The signal-to-noise ratio is an indicator of the quality of information transmission. It is the ratio of powers between:

  • the signal of maximum amplitude for which the distortion at the output remains below a limit value.
  • background noise, which is not significant information that generally corresponds to the signal present at the output of the device. In the absence of a signal at the input.

It is generally measured in decibels (dB).

Let’s consider that 1 bit corresponds to about 6 dB, I mean about ! So when calculating, 16 bits allow a dynamic range of 16 x 6 = 96 dB approximately. Because in reality we are closer to 98 dB.

So 24 bits allow 24 x 6 = 144 dB of dynamics. With 24-bit, you earn 44dB of margin. It is therefore a significant comfort! Since you no longer have to try to get absolutely close to 0 dB to get better quality.

You can thus gain in dynamics. This does not prevent the use of a console slice. For the color of its preamp, its equalization to refine frequencies during recording. Or its compressor to reduce peaks by 2/3 dB.

Tips:

EQ and compression should be applied slightly, but they are not necessary! This is one of the practical aspects of Apollo sound cards. Apply in the mixer an EQ + Compression treatment (perso I use a lot of Cambridge EQ and LA2A or 1176LN compressors). With the UAD Rec option to save the processing in the Logic audio file. And / or UAD My only for the monitoring and comfort of the artist…. Processing chain obviously reusable in Logic on playback if it has not been applied to the recording…. Sorry, I’m getting off topic….

UAD Rec/Mon

Why do some software have 32-bit resolutions?

The resolution of your sound card will not exceed 24 bits. There is no sound card that has a 32-bit resolution. So your 24-bit recordings will be encoded in a 32-bit floating point format by some software. This will not change the quality of the initial records themselves. But will create audio files in this format before they are processed by plug-ins.

My Mac works in 64 bits!

The computing resolution of your computer’s processor is probably 64-bit. This has no influence on the resolution of the 24-bit audio file recorded. This brings you more processing with your plug-ins and increased speed of your computer…

What about the sampling frequency?

The sampling frequency is the number of samples recorded per second:

  • 44.1 kHz = at 44100 samples per second
  • 48 kHz = at 48000 samples per second

the debate is more open. A frequency of 44.1 kHz is theoretically sufficient to recover the entire spectrum audible by the human ear. Now, some people perceive other things when recording in 96 or 192 kHz. Only your ear is the judge personally I work in 24 bits 44.1kHz. Simply the higher the files are in terms of sampling frequency, the more space they take up on the hard disk. This requires more processor resources for their processing through your plug-in chains. I prefer to save space on my hard disk by staying at 44.1 kHz. Knowing that very often I deliver a wav and mp3 file….

For your information, I made a 96 kHz recording once in my career. For SYLVANIA’s Marcus OPUS 1 album. A classical guitar album. My client’s request was to get closer to the quality of Alexandre LAGOYA’s recordings. I must admit that I had a very beautiful experience….

This is in Logic where you set the sampling rate.

Logic Pro X Sampling Rate

Blind testing

Perform a blind test with a file recorded at 44.1, 48 and 96 KHz. Ask a friend to do this test! Without knowing the frequencies to avoid being influenced. Maybe the difference will not exist in your ears.

Sound card and sound card!

Choosing the resolution in Logic Pro X requires quality! The converters play on the quality of the retranscription of the analog signal into digital. 2 sound cards of different brands working in 24 bits/96 kHz will not necessarily give the same rendering. This depends on the quality of the converters.

Change resolution?

If we’re in 16 bits and we want to go to 24 bits. Logic will add 8 bits in the form of zero, this does not change the sound quality of the file. If recorded in 24 bits 44.1kHz to make an audio CD. We are obliged to lower the 24-bit resolution to 16-bit resolution. You have to go through a dithering algorithm. The algorithm is independent of the quality of the sound card, it is different according to the sequencers. In Logic Pro X, we have access as shown in the image below to different dithering algorithms.

Logic Pro X Dithering
  • POWr for Psychoacoustically Optimized Wordlength Reduction
  • POW-r #1 Dithering: uses a special dithering curve to minimize the noise induced by quantification.
  • POW-r #1 Noise Shaping: uses an additional process to shape sound over a wide frequency range. This extends the dynamic range of the file from 5 to 10 dB.
  • POW-r #1 Noise Shaping: uses an additional and optimized sound shaping process to extend the dynamic range by 20 dB within a range of 2 to 4 kHz (Range to which the human ear is most sensitive).
  • UV22HR: adds an inaudible energy concentration, generated algorithmically, around 22 kHz. Technically, it is known as “Sub-Nyquist-band dither”. It is a proprietary dithering to the Apogee brand.

In the image above, UV22HR appears grayed out because I don’t have an Apogee card.

Now you know how to choose the resolution in Logic Pro X! I hope these explanations have helped you understand the importance of choosing the right resolution before making your recordings. And finally, the resolution setting in Logic is permanent. Unlike sampling frequency, which can vary from one project to another. In what resolution now will I receive your audio tracks to make your mix or mastering?