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Holy Bot

Bedroom music production, gaming and random shit

New keyboard stand, four tiers, compact living. Early December 2016.

Headroom for MP3

I’ve written about the importance of headroom when submitting your track to a professional mastering engineer, but you should also pay attention to headroom when you do this on your own and when you encode MP3s.

Okay so when the track is mastered at 0 dB (the maximum level for digital audio files) many converters and encoders are prone to clip. Lossy compression formats utilize psychoacoustic models to remove audio information, and by doing so introduces an approximation error, a noise which can increase peak levels and cause clipping in the audio signal – even if the uncompressed source audio file appears to peak under 0 dB.

In Practice

For example SoundCloud transcodes uploaded audio to 128 Kbps MP3 for streaming. In this scenario, use a true peak limiter to ensure the right margin depending on the source material. A margin of -1.0 or -1.5 dBFS should work for no distortion (sometimes -0.3, -0.5 or -0.7 would work, but it’s safer to have greater margin).

https://api.soundcloud.com/tracks/292135058/stream?client_id=3cQaPshpEeLqMsNFAUw1Q?plead=please-dont-download-this-or-our-lawyers-wont-let-us-host-audio

“Hope my haters keep a special place in their heart for me”

(via https://www.youtube.com/watch?v=72RxA5F7XEA)

https://api.soundcloud.com/tracks/288877027/stream?client_id=3cQaPshpEeLqMsNFAUw1Q?plead=please-dont-download-this-or-our-lawyers-wont-let-us-host-audio

JX-3P, TR-606, SH-101, samples, polyrhythms, gypsy scale.

Envelopes, Basics

In sound design, an ADSR envelope modulates the sound and sculpts its timbre thus changing its sonic character. ADSR is an acronym that stands for its four stages Attack, Decay, Sustain and Release. The contour of the ADSR envelope is specified by three time-parameters and one level-parameter like this:

(A) Attack time is the time it takes for the signal to go from minimum to maximum when the key is pressed.
(D) Decay time is the time for the signal to drop to the designated sustain level (if it is not set to maximum, then decay time has no meaning).
(S) Sustain level is the level of the signal while the key is hold.
® Release time is the time taken for the signal to fade out after the key is released.

Note that the signal will jump to the release stage when the key is released no matter where it is in the envelope. Hence if a short note is played, the signal might not had time to rise to the maximum in the envelope, therefore release will be relative to the level reached in the envelope.

Envelopes can be applied not only to volume, but also to filter frequencies or oscillator pitches.

To correctly tune the pitch envelope modulation range:

  1. First turn the modulation/envelope amount knob down.
  2. Press the key and set the desired minimum with the pitch knob (offset for modulation).
  3. Turn sustain level all the way up, press the key and let the signal reach maximum.
  4. While on sustain, dial the modulation knob to the maximum pitch.

About cutoff modulation, the cutoff knob is the starting point of the modulation, that means that the sound will not be altered if cutoff is set to maximum.

Moreover, it is sometimes possible to inverted the envelope and reverse its behavior.

Envelope, Basics

In sound design, an ADSR envelope modulates the sound and sculpts its timbre thus changing its sonic character. ADSR is an acronym that stands for its four stages Attack, Decay, Sustain and Release. The contour of the ADSR envelope is specified by three time-parameters and one level-parameter like this:

(A) Attack time is the time it takes for the signal to go from minimum to maximum when the key is pressed.
(D) Decay time is the time for the signal to drop to the designated sustain level (if it is not set to maximum, then decay time has no meaning).
(S) Sustain level is the level of the signal while the key is hold.
® Release time is the time taken for the signal to fade out after the key is released.

Note that the signal will jump to the release stage when the key is released no matter where it is in the envelope. Hence if a short note is played, the signal might not had time to rise to the maximum in the envelope, therefore release will be relative to the level reached in the envelope.

Envelopes can be applied not only to volume, but also to filter frequencies or oscillator pitches.

To correctly tune the pitch envelope modulation range:

  1. First turn the modulation/envelope amount knob down.
  2. Press the key and set the desired minimum with the pitch knob (offset for modulation).
  3. Turn sustain level all the way up, press the key and let the signal reach maximum.
  4. While on sustain, dial the modulation knob to the maximum pitch.

About cutoff modulation, the cutoff knob is the starting point of the modulation, that means that the sound will not be altered if cutoff is set to maximum.

Moreover, it is sometimes possible to inverted the envelope and reverse its behavior.

https://api.soundcloud.com/tracks/283985968/stream?client_id=3cQaPshpEeLqMsNFAUw1Q?plead=please-dont-download-this-or-our-lawyers-wont-let-us-host-audio

Recorded in the bedroom studio with my friend, Mysia. We are going to finish this track someday, at least that’s what we said.

Mixing with Pink Noise

Setting basic level and pan are usually the first things to do in the process of mixing. Choose a sound/channel, e.g. kick drum, to act as your main level reference, and balance all the other instruments tracks against it. So establish the initial gains and then refine with dynamics processing and stuff. That’s what I usually do.

But – here’s a neat trick to help you get the balance right: use pink noise as level reference and balance each sound/channel to it.

Generate or play pink noise at the stereo bus. Calibrate the noise to a sensible reference level that allow ample headroom on your master bus when mixing. Use an averaging meter, a RMS-type meter, to establish the level of the noise.

Start with soloing the first instrument and play it alongside the pink noise, and balance it directly against the noise by ear. That is, try to find the level at which the instrument is just audible above the noise, but not hidden. Now mute that instrument and solo the next one. Repeat. Kill the noise and voilà!

Mixing this way won’t make it perfect, but accurate enough for a start and then some.

Another (general) tip is to listen to and learn by mixers that are much better than you, and that you admire.

Note: Pink noise is a random signal, filtered to have equal energy per octave.

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