Some tips for digital audio mastering
by LMan
This small tutorial is there to give a basic impression of what's important in mastering on digital gear. There are some pointers, tips and hints to help you getting the most out of your freshly composed tune. I've got some info about compressors, mixing, and mastering. I hope this is of some use! 
Clipping In a digital studio environment, clipping is to be avoided where possible. Almost every effects plugin, mixer, etc. has an indicator for clipping - and a knob/slider to reduce volume. Check at every possible station of your audio-route if there's clipping. The loss of volume you might notice doesn't really matter if you export your audio with apropriate bit-depth later (see "Mastering" below) |  |
Compressors
Compressors are there to screen out loud peaks in audio. This usually helps to get richer sound without reaching the clipping limits. There's a rule that you can't use enough compressors, but you must employ them properly.
It's not recommended to put the whole tune through a compressor, this usually results in "pumping" sound. Use compressors on single channels of your mix, especially on drums. Again I recommend to use at least 2 different compressors for your drum/precussion sections. I always route high frequency drums (Hihats, Cyms, Claps etc.) through one compressor, and the low frequency ones (Basedrums, Toms etc.) through another one.
You'll have to experiment a bit with the settings of the compressor to get your results, there's no basic rules for that. There are settings you'll propably find on every compressor:
Threshold
The Threshold setting defines the volume level, from which above peaks will be affected by compression. That means: if you compress voice for example, and there's a loud sybillant exceeding the threshold level, it will be compressed.
Ratio
Means the compression ratio. A ratio of 2:1 for example would reduce the waves between threshold and peak to 50% (in graphical display: to half height). The higher the ratio, the more a compressor is becoming a limiter. A limiter is nothing else than a compressor with a ratio set to a very high setting (like 1:16, or in some cases 1:infinite). This explains the term: the wave material is being limited to the peak volume defined by the threshold value.
Attack/Release
Here you can add delays to the compression. With drum sounds for example, it's often good to delay the attack of the compression (the word delay used in its normal meaning here, not for a delay effect ;), so the percussive "drive" of the sound doesn't get lost. A suitable release setting helps with reducing unwanted pumping effects.
Mixing and EQ
I found that it improves the sound if you keep every track in it's own frequency range. That means: Don't have too much bass in lead sounds, else you'll get the bass muddy. Don't have too much treble in lead sounds, or you'll drown your hihats. Don't have too much mid frequencies in your hihats, or you'll interfere with your lead sounds. You see where I'm getting at? ;) But this is no basic rule, it's just a pointer to keep your tracks "acoustically seperated" - which results in a clearer sound.
Try placing sounds somewhere else in the stereo space than only center. ;)
I guess it would be helpful to have good monitoring speakers when mixing/mastering. If you don't own one of these (like me), I recommend listening to the mix on various gear (headphones, big/small speakers, car) to detect flaws in your mixing.
You should readjust mixing at least once after an appropriate break for your ears (preferably on the next day). You'll find it sounding very different from the day before... Walk through the room to get different impressions of your mix. There can be resonant spaces in your room, where i.e. bass frequencies sound very much louder than elsewhere. It also often helps to compare your mixing to a well-produced tune resembling the style you want to create.
Mastering
In a digital studio environment, produce the mixdown with 44100 Hz, and 24 bit resolution (or more) to prevent digital noise or loss in dynamics. It's not nessecary to run a normaliser based on maximum peak level, the final limiting/dithering unit should take care of that (like the Waves Ultramaximizer). You can use a multiband compressor as a master effect now to punch up or reduce certain frequency ranges of your tune, and to get closer to the soundscape you desire.
The Ultramaximizer is one of the most vital tools when mastering. It shold be set to 16 bit dithering now (for CD-compatibility). Most likely there'll be a preset for that. Now adjust the threshold level to gain as much volume as possible without losing dynamic vitality of the tune (and without causing distortion/clipping). Do it, but don't overdo it! ;) Now you can export your 16-bit 44100 Hz for burning on CD/compressing to mp3.
- LMan -
PS: If you feel there's something missing or even wrong in this small tutorial, please contact me.
Compressors are there to screen out loud peaks in audio. This usually helps to get richer sound without reaching the clipping limits. There's a rule that you can't use enough compressors, but you must employ them properly.
It's not recommended to put the whole tune through a compressor, this usually results in "pumping" sound. Use compressors on single channels of your mix, especially on drums. Again I recommend to use at least 2 different compressors for your drum/precussion sections. I always route high frequency drums (Hihats, Cyms, Claps etc.) through one compressor, and the low frequency ones (Basedrums, Toms etc.) through another one.
You'll have to experiment a bit with the settings of the compressor to get your results, there's no basic rules for that. There are settings you'll propably find on every compressor:
Threshold
The Threshold setting defines the volume level, from which above peaks will be affected by compression. That means: if you compress voice for example, and there's a loud sybillant exceeding the threshold level, it will be compressed.
Ratio
Means the compression ratio. A ratio of 2:1 for example would reduce the waves between threshold and peak to 50% (in graphical display: to half height). The higher the ratio, the more a compressor is becoming a limiter. A limiter is nothing else than a compressor with a ratio set to a very high setting (like 1:16, or in some cases 1:infinite). This explains the term: the wave material is being limited to the peak volume defined by the threshold value.
Attack/Release
Here you can add delays to the compression. With drum sounds for example, it's often good to delay the attack of the compression (the word delay used in its normal meaning here, not for a delay effect ;), so the percussive "drive" of the sound doesn't get lost. A suitable release setting helps with reducing unwanted pumping effects.
Mixing and EQ
I found that it improves the sound if you keep every track in it's own frequency range. That means: Don't have too much bass in lead sounds, else you'll get the bass muddy. Don't have too much treble in lead sounds, or you'll drown your hihats. Don't have too much mid frequencies in your hihats, or you'll interfere with your lead sounds. You see where I'm getting at? ;) But this is no basic rule, it's just a pointer to keep your tracks "acoustically seperated" - which results in a clearer sound.
Try placing sounds somewhere else in the stereo space than only center. ;)
I guess it would be helpful to have good monitoring speakers when mixing/mastering. If you don't own one of these (like me), I recommend listening to the mix on various gear (headphones, big/small speakers, car) to detect flaws in your mixing.
You should readjust mixing at least once after an appropriate break for your ears (preferably on the next day). You'll find it sounding very different from the day before...
Walk through the room to get different impressions of your mix. There can be resonant spaces in your room, where i.e. bass frequencies sound very much louder than elsewhere. It also often helps to compare your mixing to a well-produced tune resembling the style you want to create.
Mastering
In a digital studio environment, produce the mixdown with 44100 Hz, and 24 bit resolution (or more) to prevent digital noise or loss in dynamics. It's not nessecary to run a normaliser based on maximum peak level, the final limiting/dithering unit should take care of that (like the Waves Ultramaximizer). You can use a multiband compressor as a master effect now to punch up or reduce certain frequency ranges of your tune, and to get closer to the soundscape you desire.
The Ultramaximizer is one of the most vital tools when mastering. It shold be set to 16 bit dithering now (for CD-compatibility). Most likely there'll be a preset for that. Now adjust the threshold level to gain as much volume as possible without losing dynamic vitality of the tune (and without causing distortion/clipping). Do it, but don't overdo it! ;) Now you can export your 16-bit 44100 Hz for burning on CD/compressing to mp3.
- LMan -
PS: If you feel there's something missing or even wrong in this small tutorial, please contact me.