Studio Home

Recordings
Jazz
Pop Hits
Rock & Roll
Latin (Pan American)
Classical Music
Fusion
Bach
Reggae
Dance
Pop Hit Songs
New New Music
Meditation
Em4U (Electronica)
Stephen Gislason
Download Help

Topics from the book,
The Sound of Music

Music Theory
Musical Brain
Synthesizers
Pitch and Tonality
New Music
Music Instruments
Composing
Scales and Chords
Arpeggios
Rhythm
MIDI
All About Sound

Audio Processing Components

Compressor /Limiter

A compressor automatically controls the volume of an audio signal. Its main function is to avoid transients that exceed tolerances of the recording system and cause clipping. You set a threshold level and tell the compressor how quickly to react and it limits the volume.  In a digital mixer 0dB is maximum before clipping occurs and recording peaks are best kept below -1dB. Compression can begin at -20dB. The compressors negative gain is determined as a ratio. A ratio of 5:1 will reduce the input signal (5) to an output of 1dB over the threshold. When the sound volume falls below the threshold level, the gain returns to normal. The attack time determines how long the compressor takes to reduce the gain. The release time determines how long the gain takes to return to normal after the input signal has fallen back below the threshold. Compressors  often have the option of the “knee.” A soft-knee compressor increases the compression ratio gradually as the volume approaches the threshold. A hard knee responds as quickly as the attack time specifies.

While a compressor may be the most useful and necessary of all audio processors, its proper use requires technical knowledge, experience and good judgment.  Final decisions are made by listening and not technical preconceptions. Recording performances through a microphone may require some compression at the source. Vocal recordings tend to be the most demanding unless the singer is a real pro. Use a capacitor microphone for vocals, placing the mic about nine inches from the singer’s mouth. Use a pop shield. Vocal compression should  be minimal - just avoid clipping-  up front to avoid losing dynamics that cannot be restored later.

Some Quick Mixing Tips

Reverb creates the illusion of space, but interferes with stereo localization. To maintain stereo placement, use a mono reverb panned to the same position as the original dry sound. Reverb can make vocals better but tends to push the vocals back in the mix when they should be up front. Pre-delay values of 60-100mS and early reflections reinforce the dry sound. Avoid reverb on bass sounds.  Use a short ambience program or a gated reverb to add space to a kick drum.

Equalization is often used to fix sound that was not correct at the source. Reducing the frequencies that are too prominent is better than boosting the weaker ones. Sounds that are pleasing alone may not sit well in a mix.  The fix is sometimes to use high- and/or low-pass filters to restrict spectral content. Low frequencies, 200-400HZ, are produced by many instruments and may selectively filtered to avoid mix mud.

Dry mix until you are pleased before you add any effects or signal processing. Effects are best used a finishing touches. Vocals with pitch problem can be fixed with pitch-correction processors. Enhancers are best used on specific sounds  in a mix to make them stand out. Use the enhance in a separate bus and send only the selected sounds that need enhancing.  Adapted from Paul White’s Tips, Sound On Sound, July 1999

Staying Dry: Effects (wet) are added to an original sound (dry) creating a dry/wet ratio. My goal is to create dry mixes that are very good without any compression, equalization or reverb.  Recordings using electronic keyboards and synths have many options for sound crafting without using effects. 

Careful mixing with faders set properly and volume envelops on each track acts as a deliberate, controlled form of compression. I reserve compressors for the mastering stage when each composition must fit into the meta-composition of an album. I use a volume ceiling of -2dB for competed recordings and try to achieve that with minimal compression.

We Seek Audiophile Perfection  We make great music at Persona Digital Studios. We have many years of experience with computer based sound recording and enjoy technology shop talk. We also have a well developed interest in how our brains process sounds. Our in house music production creates audiophile quality recordings presented as CD's, DVDs, singles and albums for Download.  Music Downloads are albums, packaged as MP3 files in a zip folder. Download  the zip folder and save.  In Windows, click on the folder and choose the extract all option to unzip the files to your hard drive. The MP3 files will play on all computers, laptops, notebooks, smart phones, iPods,. iPads, CD and DVD players and all portable music players. Some albums contain liner notes or minibooks as PDF files that introduce the music. More About Downloads.

Persona Digital Studio is located on the Sunshine Coast, Sechelt, British Columbia, Canada.
 www.personadigitalstudio.com  email  music@personadigitalstudio.com.
Our Music Catalogue includes recorded performances by the P2500 Band, Em4U, and the Persona Classical Consort.
Music downloads and books are available from our companion website: Persona Digital Online.