Join Alex U. Case for an in-depth discussion in this video Creating reverb mechanically using springs and plates, part of Foundations of Audio: Reverb.
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Acoustic reverb for studio recording comes in the form of carefully designed and cleverly captured room tracks and reverb Chambers. The next class of Reverbs are those that use some sort of mechanical system to create a useful resonance. Mechanical reverb today comes in two forms, springs and plates. Spring Reverbs are made of, well just that, springs, usually a network of interconnected springs. A spring vibrates in a fairly simple way. Give it a shake and the vibration zips back and forth from end to end along the length of the spring.
Multi-spring Reverbs make a mechanical connection between springs to trigger several interactive resonances among those springs. Let your audio drive the springs into action, pick up the subsequent vibration, and you've now tapped into the mechanical resonance of the springs as a kind of analogy for acoustic reverb. The sustained vibration of the springs proves useful in audio as a specific flavor of reverberation. It never sounds exactly like a room, but it certainly has a unique and interesting quality.
Spring reverb, because it's light and portable and quite affordable is common in many old organs and guitar amps. Partly for the convenience, but also because of its characteristic sound, spring reverb remains an essential part of guitar tone. It's a defining element of surf music and guitar-based blues, but it is by no means limited to guitar alone. Let's hear a quick example. First, the electric guitar without spring reverb. (music playing) Now let's hear it with some of the amps spring reverb.
(music playing) As you'll see later in this course, spring reverb is a great way to modify the timbre of an instrument. While it may not evoke the sense of a concert hall or a nice sounding room, it does offer a quality of resonance that's desirable on many tracks. Plate Reverbs offer an increase in sonic complexity over spring Reverbs.
Where springs vibrate in a relatively simple one-dimensional way from end to end, a plate reverb, made up of a large plate of metal, will vibrate in a more two-dimensional way, down the length and across the width of the sheet of steel. An audio signal feeds a driver, which is connected directly to the plate, causing it to vibrate. Imagine a two-dimensional room, a room with length and width, but no height. As with springs, plate resonance doesn't actually sound that much like a real room.
Here's a snare head, first dry, then through a plate reverb. (music playing) With experience you'll learn to identify the strong upper mid frequency decay characteristics of good plates and how they sound quite different from springs, rooms, and halls.
Plate Reverbs haven't been made commercially in decades. The vintage units are highly sought after, expensive, and frankly, they're quite heavy. So it's quite common use convolution reverb to accurately get the sound of an actual plate into your mix. We cover convolution in a movie later in this chapter, but we use it here to add plate to the snare head. Listen carefully for the textured resonant decay as I gradually add plate to the snare drum while David plays time on a drum kit, where we've placed kick, snare, and a pair of overhead microphones. (music playing) The presence of reverb is unmistakable, but notice also that it doesn't sound anything like a concert hall or cathedral.
Like springs, plates are desired for the distinct sonic coloration that we used to modify the timbre of the instrument's synth. Springs and plates are mechanical systems that offer their own unique strongly flavored sort of resonance, and while their mechanical technology is hardly cutting edge--digital is the thing these days-- their sound is still relevant. They're so important to music recording still that digital Reverbs of today often have presets that emulate these mechanical Reverbs of the past.
You'll see that plates and springs are used often in the audio examples throughout this course. We study digital Reverbs next.
These techniques can be practiced with the free Get in the Mix sessions, currently available for Pro Tools and Logic Pro.
- What is reverb?
- Understanding how acoustic reverb works in rooms
- Working with the signal flow, effects loops, and available CPU resources
- Understanding core parameters, like reverb time and pre-delay
- Simulating space
- Creating nonlinear reverb
- Building pre-delay effects
- Using reverse reverb
- Using convolution correctly