Being asked by Premier Guitar to write an article about lesser-known vintage spring reverbs was like a chocoholic being asked if he’d like to become head taster for Willy Wonka. As the founder of Soundgas Limited, my self-proclaimed remit over many years has been to seek out and explore vintage and unusual recording gear, with a particular emphasis on effects—especially electromechanical echoes and reverbs. Based in Derbyshire, U.K., Soundgas supplies a unique range of classic, esoteric, and exotic music-making equipment to a stellar international client list. As soon as the remit for the article was confirmed, I set about sourcing as many vintage spring reverbs as I could find in the limited time available.
If, like me, you grew up in the pre-digital age listening to music radio, you’ve heard countless examples of classic spring reverbs in action. From subtle sweetening ambience to canyon-esque magnificence and surf-drenched tsunamis, popular music is awash with the sound of the spring reverb.
I was a music-hungry teenager when I first became aware of the spring reverb as a distinct entity. The mid-to-late-’70s U.K. music scene was enriched by the coming together of punks and dreads, united by common bonds of alienation and exclusion. The Clash were my introduction to reggae legends Junior Murvin (Police & Thieves) and Willie Williams (Armagideon Time). We became aware of Lee “Scratch” Perry and King Tubby, and marveled at the exotic and otherworldly sounds of Jamaican sound-system culture. This was to have a profound and lasting influence on my future life: Without dub music there would be no Soundgas. The wild, rolling repeats of endless tape echoes, deep organic phasing of guitars, hi-hats, and organs, and of course the thunderous crash of abused spring reverbs—sounds that, to this day, are manna to me.
Prepare to Reverberate
Ever since the introduction of outboard spring reverbs, classic models that are commonplace in the U.S. have been about as common as hens’ teeth in the U.K. Even with the advantages of the internet, these are difficult to acquire for comparison’s sake without exorbitant cost. The most glaring omission you’ll find here is the original, tube-driven Fender Reverb—although plenty has been written about this fantastic unit elsewhere. We did have the British answer to the Fender in hand, in the shape of a rare, nicely restored 1963 Vox Echo Reverberation Unit. In total, I directly compared over 25 vintage spring reverbs and half-a-dozen modern pedal options.
Before we dive into the springs, I have to confess that I cannot fairly describe myself as a guitarist. I enjoy making noises with guitars and effects, and have had a lifelong passion for all things guitar related, but it’s unlikely I’ll be interviewed in these hallowed pages about the secrets of my technique and tone. Sound is my thing: The studio and its myriad sonic playthings are my instruments, and spring reverbs are a particular passion—the weirder and less known, the better. For the purposes of comparison, I used a loop pedal with guitar parts played by a member of the Soundgas team, Joel Kidulis, to ensure there was no deviation in playing.
Along the way, there were a few surprises, with some units completely confounding my expectations. Perhaps unsurprisingly, some springs we rate highly for studio and mix use fared less well with guitar, having not been designed for that type of input. Others have very short springs and are more suited to vocals. Some that we prize for their unique character sounded noisy and uninspiring with guitar. As a result, I edited my original selection down to the highlights. I’ve given some background on particular units and brief notes on performance, but please check out the sound examples for the real lowdown.
Background Noise
While this article is not intended to be a definitive guide to all things spring, some background history and technical detail is necessary to understand the nature of the various units on test.
The first spring reverbs were large, oil-filled devices developed by Bell Labs to simulate the delays caused by long-distance telephone cables. In 1939, Laurens Hammond employed this new technology to add church-like ambience to his organs. Over the years, Hammond engineers improved and refined the company’s spring reverbs, reducing them in size and weight, until in 1959 the Hammond (later Accutronics) Type 4 was born. Featuring two long springs inside a 16" metal case, the Type 4 soon became the industry standard. Hammond licensed the design to other manufacturers, including Leo Fender, who used it in his 6G15 Fender Reverb in 1961. In 1963, the Fender Vibroverb became the first guitar amp to feature onboard spring reverb.
Evolution of the spring tank: The original Hammond Type 4 tank (top) has a brass-like hue on the underside of its welded chassis, while sister company Gibbs’ version (middle) is almost identical save for the sharp corners, and the competing O.C. Electronics Folded Line Reverberation Tank (bottom) (with its famous “Manufactured by beautiful girls” label, inset) houses its innards in a tray made from a single piece of bent metal.
Initially, Type 4 tanks were produced in-house at Hammond, with production moving in 1964 to Gibbs Manufacturing, a Hammond-owned facility in Janesville, Wisconsin. In 1971, it moved to another Hammond company, Accutronics, in Geneva, Illinois. One of Accutronics’ biggest competitors—formed by ex-Gibbs employees—was O.C. Electronics, whose Folded Line Reverberation Tank was used in Roland's Space Echo series and bore the legend: “Manufactured by beautiful girls in Milton, Wis. under controlled atmosphere conditions.”
Spring reverbs can be divided essentially into two camps: those that passively mix the spring output with the dry signal, and those that use a make-up amp or buffer circuit to add gain to the signal. The two biggest factors in the sound quality of a spring reverb are type and design of the drive circuit and the tank. Most units feature two or three springs. Two sound more fluttery and “vintage,” while three tend toward a richer, smoother, fuller sound with more low end.
Listening to the clips, you’ll find that some of these units are capable of creating way more than ambience. Whether driven by germanium transistors, 4558 op amps, or discrete preamps, vintage spring ’verbs tend to have a wealth of tonal colors lurking beneath their surfaces. Pushed hard, many can get properly nasty. And sure, they’re not exactly pedalboard friendly, but the tones from their drive circuits can rival some of the most coveted vintage overdrive and fuzz pedals.
Listen to most of the reverb units in a direct comparison.
Meet the Lords … and Gollums
1963 Vox Echo Reverberation Unit
Made in the U.K. by Jennings Musical Instruments, Tom Jennings’ answer to Leo Fender’s Reverb uses an EZ80 rectifier valve, as well as two 12AX7s and one 12AU7. It has two input channels to Fender’s one. These early units are very uncommon. Later in 1963, following an endorsement deal with the Shadows singer, they became known as the Vox Reverb Unit (Cliff Richard Model).
The Vox’s unusual design incorporates two sets of springs and four delicate ACOS crystal phono cartridges instead of the Hammond tank’s pickups and transducers. According to Vox designer Dick Denney, this was to circumvent the Hammond patent and avoid having to pay license fees. As you increase the level of the spring, the overall output level drops, so careful balancing of amp and effect can be required to achieve the desired sound. The crystal pickups in these units do not withstand the passage of time and this particular unit has had modern replacement phono cartridges installed to keep it as authentic as possible, though I personally feel it would probably sound much better with a Hammond tank! It’s a subtle yet warm and sweet effect that suits guitar well but is less likely to appeal to those seeking a wetter surf-type sound.
Grampian Reverberation Unit Type 636
I could write a whole article about this unremarkable-looking, gray Vynide-covered box from the U.K. It’s a true wolf in sheep’s clothing that links the Who’s windmilling guitar genius, Pete Townshend, with the godfather of dub and remixing, Lee “Scratch” Perry. Townshend discovered that plugging a guitar into the Grampian’s mic input—whose germanium circuit is very close to an early Fuzz Face—delivers a rich, distorted fuzz effect, which is why he employed one in the studio and onstage for many years. Meanwhile, Perry installed one in his Black Ark studio. In fact, Grampian reverbs graced many recording studios in the ’50s and ’60s.
Type 636s do not accept quarter-inch jacks, and instead use BBC/GPO type-b quarter-inch sockets. The mic input has balanced and unbalanced options, and there are two auxiliary channel inputs. The 10 mV, 50k ohm input is great for guitar—and also for maximum distortion levels. The second input is 500 mV and 1M ohm, and its output is rated at 1V 600 ohms. Controls include an on/off toggle, reverberate (reverb level) knob, and input gain controls for the mic and aux channels, which link to the overload-lamp circuit. The lamp is an integral part of the driver circuit: If it’s not working or of the wrong value, performance can be adversely affected.
The 636 is capable of smooth, rich reverb with low noise. However, given the age of the original germanium transistors, many unrestored examples are now quite unstable and noisy. We have a couple in the studio—one with the original Gibbs tank, and one with a replacement Accutronics tank—and we use them extensively for coloration. Both are featured in our sound samples for comparison. Initially, I expected these units to be some of the noisier reverbs in the test, but they performed better than most. A well-restored Grampian is a great contender if you want a high-quality studio or guitar spring. But it’s when you overdrive them that the real magic happens: The degrees of luscious filth on offer are widespread, controllable, and utterly sensational.
It’s hardly surprising that, as awareness has grown, 636s have become very sought after, with prices now well into four figures—even for units that need servicing. However, because they look so humdrum, they’re still sometimes thrown away as garbage. (The last one we got was saved at the last minute!) We’ve seen a fair few come and go at Soundgas and have successfully restored many. We’ve also seen a good number butchered by those attempting repair without fully understanding the circuit. Many were powered by a large, lantern-style 9V battery that can leak acid over time. I’ve seen 636s with the tank and much of the metal chassis completely eaten away. In addition, sustained high input levels can burn out the all-important pilot lamp bulb. Be very cautious if you’re considering purchasing one that hasn’t been refurbished, as few are likely to function as they should.
As mentioned previously, both my Grampians were in action for the shootout, but one developed a fault with the Gibbs tank. Our tech, “Doctor” Huw Williams, fitted it with an Accutronics tank to keep it in the game. The one still outfitted with a Gibbs tank is battle scarred, a little cranky, and somewhat noisier (all Grampians have a degree of hiss—the price you pay for that germanium magic), but it sounds more to my taste than the Accutronics-fitted one. But then, I like dark, warm, and mellow. The revived unit still has that fabulous break-up, but the Accutronics tank sounds brighter, much louder, and more reverberant—which gives me a compelling reason to keep both!
Soundgas is currently working on a new version of the 636. If we can get the sound right, we plan to build a few to order—although the scarcity of good new-old-stock (NOS) components means it’ll likely be a very limited run.