Doepfer A-199 Spring Reverb

Let's have a look at the Doepfer A-199 Spring Reverb, a spring reverb unit for Eurorack modular synthesisers. The A-199 is surprisingly good value at around £120 new or £80 on the used market, and there are lots on the used market, because spring reverbs are irresistibly appealing but also very limited.

What's a spring reverb? It's an electronic effect that uses springs to simulate the sound of an empty room. Nowadays the sound is indelibly associated with 1960s surf rock, because Fender started to include spring reverbs in their amplifiers at exactly the same time surf rock took off. The basic sound is all over Les Jaguar's "Guitare Jet", along with masses of tremolo:

But there were spring reverbs in the classic old EMS VCS-3 and ARP 2600 synthesisers from the 1960s and 1970s as well, because they were intended to be compact all-in-one units that could do everything. As a kid in the digital 1980s I remember being amazed at the thought of an effects unit that used springs instead of digital circuits.

Victorian-era springs. Here's what the inside of the A-199's spring tank looks like:

An electrical loudspeaker at one end of the unit makes the springs wobble; at the other end of the unit a circuit converts the wobbles back into sound, but because the signal has been wobbled with springs the sound is wobbly. Wobbly in a complex way. That's how a spring reverb works.

The Doepfer A-199 comes in two parts. There's the faceplate, which has the controls and power supply, plus a separate reverb tank. They connect up with some cables.

The springs pick up electrical interference, which is why the tank is a separate unit, so that you can place it far away from your Eurorack power supply. In practice I found that the power supply in my Doepfer LC6 wasn't an issue, but I had interference from my MOTU audio interface, which was just underneath the LC6; when I moved it away the interference stopped.

Siting the tank is awkward. Doepfer expects you to mount the tank inside the case, using the rubber washers to insulate the tank against physical knocks. Sadly my LC6 doesn't have space to put the tank anywhere sensible. I found I could rest it on the bottom of the case, but there was slightly too much interference if I did that.

For a while I mounted it like this, outside the case:

It worked, but what if the tape lost its grip? Furthermore there's the issue of routing the cables from the back of the A-199 to the spring tank. In the end I gently hacksawed an opening in the top-right of the A-199 and put the tank in a little plastic box underneath my LC6.

Spring reverbs have a distinctive sound. Like the inside of a metal shipping container. There's no way to change the length or density of the reverb, short of using a larger or smaller tank. In my experience the effect thickens up the sound nicely at low settings, and at high settings it makes everything sound like a David Lynch movie. It also has a lo-fi, retro quality to it, not just because of the surf rock connection but also because it introduces a lot of noise. Not necessarily a bad thing. In the following clip the grinding, pulsing noise that comes through clearest in the last minute or so is the sound of an A-199 fed through a compressor (which amplifies the noise) and digital reverb, which smooths the noise into a wash of sound:

Here are some isolated examples. In the first sound clip I play a loop with my Behringer RD-8 drum machine, gradually turning up the effect volume. Mid-way through the track I introduce some more effects in order to show how the spring reverb can be used as part of a mix:

Ashley Pomeroy · Doepfer A-199 Spring Reverb: From Dry to Wet

In the second example I'm using the A-199's feedback input to send the signal into a filter, then back into the unit again:

Ashley Pomeroy · Doepfer A-199 Spring Reverb: Feedback

The result is a distinctive metallic sproing sound. Ordinarily the feedback circuit feeds the reverb signal back into itself. You'd expect this to create an enormously long reverb signal, but disappointingly it just makes a feedback howl. In moderation the howl is soothing, but it gets old quickly. The other control is emphasis, which boosts the mid-range a little bit.

In this video I mess around with the unit for five minutes while playing a bassline through it.

In this video I use it in a piece of music. It's part of the effects chain for the swoopy noise that flies around the other instruments. The sound is coming from a mixture of Plaits and a Behringer TD3, fed through a spring reverb, then a filter and some digital reverb:

Surprisingly for a modular unit the A-199 doesn't have any voltage controls. If you want to modulate the reverb you'll have to feed the signal through a mixer or filter, and modulate that instead.

Of note my A-199 is the third model. The original A-199 was 10hp wide, with the "feedback" and "emphasis" labels written out in full. The second model slimmed the panel down to 8hp, and the third model added jack plugs instead of soldered connectors for the spring tank. If you're listening, Dieter Doepfer, I would be very grateful if you could add a little cut-out in the front panel - perhaps with a plastic tab, or a rubber grommet, or a flap or something - so that the cables can route out of the case.

Does the A-199 make any sense? At low levels it works perfectly well purely as a means of thickening the sound without changing its character. At higher levels it sounds lonely, distant, metallic, like the bits of a Godspeed! You Black Emperor song in between the violins. At 8hp it's not excessively big, although the need to find somewhere to put the tank is awkward. It's not particularly expensive.

On the other hand almost every digital reverb unit made in the last forty years has a spring reverb simulation, and the howling sproinging crashing noises that are characteristic of spring reverbs are a novelty that quickly wears off. Nonetheless there's something psychologically appealing about having actual springs. Actual physical springs. Just like the BBC Radiophonics Workshop.

Actual. Physical. Springs. And that's the Doepfer A-199.