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The Basics of Spring Reverb (+ Audio Examples)

Transcript
Alright, now we’re going to talk about analog reverbs. Analog reverbs are mechanical devices that are used to recreate the sound of sound in a space, and they do it through some pretty interesting means.

Now, rather than get right into the technical heady stuff, what I’d like to do is play some sounds, and then start dissecting them and explain the mechanisms that make them sound the way that they do.

So before we get into that, let’s first hear the record dry.

[mix]

Alright, the first thing I’m going to bring in here is a spring reverb. This is an analog spring reverb that I’ve got feeding in real time. Here we go.

[mix, vocals with spring reverb]

Cool. This next one that I’m going to play is a plate EMT 140. This is an actual hardware unit that my friend Bob Horn ran for me so that I could give you this example. I don’t have a plate. They tend to be hard to get.

[mix with plate reverb]

Cool. So now what I’m going to do is solo the vocals and start soloing the reverb returns so we can start to hear some of the differences.

[vocals without reverb]

First our spring.

[vocals with spring]

Now our plate.

[vocals with plate]

Cool. So now, let’s listen to the reverbs in solo, and then start breaking down the differences that we’re hearing.

[spring reverb]

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That was the spring. Here’s the plate.

[plate reverb]

Cool. Alright. Here we go.

So a spring reverb, the way that it works is basically, you have a transducer. A transducer is the same thing that drives your speakers, it’s the same thing that’s on the end of a microphone. Basically, it’s something that vibrates, and through its vibration, creates current, or the other way around. Current causes it to vibrate.

You’ve got one of those stuck to the end of a spring that is held in tension through some kind of a chassis. That spring then starts to vibrate as a response to the transducer vibrating. However, because it’s a spring and it’s held at tension, the vibration causes sympathetic vibrations, and it continues to resonate. So meaning, even if you take the spring and you just do one pressure change, like that, a wave will go down the spring, return, go up, go back, and there will also be sympathetic waves going on in between, just like a string if you were to play, say, a violin or pluck a guitar. You get all sorts of these different sympathetic vibrations.

So on the other end of that is a transducer, basically acting as a microphone or a pickup, and that ends up being the sound that is recorded back in.

So because you get this continual resonance, you end up getting a decay, and because of its ghostly characteristic, the tone of it ends up sounding like reverb in a room, and actually, in a lot of ways, it is. If you think about it, reverb in a room is just a series of transverse waves.

Well, a spring being vibrated is literally a transverse wave. It is exactly the same thing. It is a standing wave being produced and resonating. If you have, say, three of them, which most springs or many springs do. Some have two, some have three, some have one. Not too many have one.

It creates a more complex set of reflections, and it ends up sounding fairly similar at least to what we think of as reverb. In terms of the tonality, because we have these discrete transverse waves, we end up with what we call very low diffusion echoes. The spring reverb can be defined as something that is both not dense, and also not diffused, meaning we don’t have a lot of dense sound resonating together, and the parts that are dense are fairly far apart, and when we listen to it, we actually hear that in its texture. It’s what creates this sort of ripple-y sound, believe it or not. [laughs]

Okay, don’t shoot me.

[spring reverb]

So you can hear that it almost has this, like, ridged texture to it in an interesting way. It almost sounds like you can hear separate echoes. And if I were to pull up say, a cheaper plate emulation, it would sound like this.

[plate emulation]

Where it actually sounds like a series of delays that are very close together. Most spring reverb is basically that. The other things that we’ll notice about springs is they’ll tend to have very specific frequency resonances, meaning when we hit certain notes and certain things, it will ring in a particular way. This is going to be determined by the gauge of the wire that’s used in the spring, the diameter of the wire that’s used in the spring, the tension that’s on the spring itself, all of these things come together to create its modal response, which is what ultimately gives it its tone, and so you’re going to have springs that are bright and plinky, you’re going to have springs that are darker, you’re going to have springs that are more mid-focused, and everything in between.

[spring reverb]

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Matthew Weiss

Matthew Weiss

Matthew Weiss is a Grammy nominated and Spellemann Award winning audio engineer from Philadelphia. Matthew has mixed songs for Snoop, Sonny Digital, Gorilla Zoe, Uri Caine, Dizzee Rascal, Arrested Development, 9th Wonder, !llmind & more. Get in touch: Weiss-Sound.com.

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