The wonderful world of what is generally referred to as “time-based processing” is a powerful tool to the audio engineer and the sound engineer technician, and one we teach to our students in our audio engineering school.
These processors, whether in plugin form or dedicated hardware boxes, provide the tools to create a variety of “acoustic spaces” that give our productions a sense of depth, space and openness. They can also be used to to “beef up” and re-enforce sounds in the mix or just get plain “out there, man.”
Time-based processing usually falls into four main categories:
Reverb, short for reverberation, is a series of closely spaced, random echoes. If you’ve ever been in a parking garage or concrete stairwell, you’ve experienced reverb. How long the reverb hangs around, or decays, is measured in seconds.
There are various reverb “styles” as you may have seen in the presets of your reverb plugins and boxes.
“Plate” style reverb is an attempt to recreate the sound of a mechanical reverb device that uses a resonating metal plate and has a signature sound quality. “Hall” style reverb is the kind of reverb you might hear at a concert hall. You get the idea.
A big part of what makes these “types” of reverb sound different is the amount of high frequency content, diffuseness of the reflections and early reflections, and the randomness of the echoes. There is a lot of power in those adjustments, so play around with them and see what sort of cool “spaces” you can create.
One of my favorite ‘verb combos is a short “room” style reverb with a decay time of well less than a second and a short pre-delay (under 20 ms). It gives a nice, subtle “halo” of space and air around the sound without sounding washed out and “reverby.” Then I use a “plate” reverb with a longer pre-delay (40-50 ms) and decay of about 1.2 to 1.5 sec for the more noticeable reverb “tails.” The “room” sound sits nicely in the pre-delay of the “plate” then the plate takes over, kind of blending everything together nicely.
Echoes are just what you’re thinking. A repeat of a sound. Echoes and delays are used in a bunch of ways. Measured in milliseconds, echoes and delays can create thickening effects, doubling effects and the more obvious “HEY, Hey, hey, hey” type of effects.
A feedback control is usually found on these types of effects and that is the parameter that adjusts how many echoes are created. An old school doubling effect is to send a sound to a delay device with a short delay time, say 25 ms, with 0 percent feedback and then pan the original sound left and the delay sound right in the mix.
On guitar, it’ll sound like classic tracks from Jethro Tull’s Aqualung album or David Bowie’s Ziggy Stardust. Another classic is the “tape slap” effect. This time, try the delay time at about 150 ms with very little feedback for an Elvis Presley sort of vibe on vocals or guitar. To thicken up some vocals, try even shorter delay times down to around 20 ms and blend into the original sound. Go with considerable longer delay times for the “Grand Canyon” types of echoes. A 1000 ms delay time is equal to one second.
Modulation effects rely on a varying, or modulating, of phase relationships between audio signals. Chorus, Flange and Phaser effects all rely on similar techniques to create their sound. They can be used to add richness and depth to sounds, particularly sustained sounds.
See Omega engineer Jim Curtis’ video on flanging effects using a tape machine for a look at how this effect used to be done “back in the day.”
In most of these effects, there with be a “rate” control that adjusts the speed of the modulation from a slow sweep to a fast warble and a “depth” control which controls how far, or deep, the modulation swings.
On you next mix, try some “chorus” on the background vocals, “phaser” effect on the guitars and one of my favorites, some flanger on your reverb tails!
4. Pitch Shifting
Pitch in this regard should not be confused with “pitch correction” (think “Auto Tune”) as it is commonly thought of today. Pitch shifting is more along the lines of an “Alvin and the Chipmunks” kind of shifting of pitch. This type of effect generally falls under the time-based umbrella, at least traditionally, because a digital delay line (DDL) was often used to create it. As the delay time was lengthened, the pitch would drop.
The deep “I’m disguising my voice and hiding my face on TV interview” effect, as well as pitching the voice up to the “silly helium sound,” are classic examples of pitch shifting.
Tape machine speed variations are the old school way to do this and typically has a smoother sound than a DDL for the same effect. It can be a fun way to add some interesting effects in your mix. Most DAWs have a plugin for shifting pitch. A cool one is to send a sound to a pitch shifter and and pitch it down an octave to blend back in to add some instant weight to a track.
Have fun with it all and happy mixing!!