As I started researching and writing this story, it slowly dawned on me that guitar synth effects fall into two categories: the compact stomp-sized units and what I term the "big beasts"—the rare and desirable monsters that stretch the definition of “effect pedal.” While there are some superb compact pedals, it’s these gargantuan boxes that really set pulses racing with the epic scope of their designs, the wild and unpredictable sounds they create, and their sheer “I want one of those,” GAS-inducing magnificence. So for this story, I donned my pith helmet and stuck to big game.

My fascination for weird old gear stretches back several decades to when we built our first studio in a friend’s tiny basement and could only afford essentials. Scouring ads and garage sales for discarded and unfashionable gear became the habit that would eventually lead me to create my company, Soundgas.

Seeking to replicate otherworldly and elastic electronic noises I’d heard on early-’70s LPs by Stevie Wonder, Pink Floyd, Parliament, and Kraftwerk—and without the benefit of the internet for research—I started chaining together old guitar pedals and running them into the external filter inputs of cheap analog monosynths. My squelchy sonic nirvana came courtesy of a battered Copicat tape echo together with old fuzz, phaser, and wah pedals, and our Korg MS-10 or Yamaha CS-5 synths.

As I considered the definition of a “guitar synth effect” for this article, it struck me that I got pretty close all those years ago. That motley assortment of thrift-store-worthy gear, connected by ragged and scavenged cabling, comprised the essential elements of an analog guitar synth effect.

What’s in a Name?

So, what defines a guitar synthesizer effect? The final word of that question is key. In this article, I’m covering effects that produce synth-like sounds from any electric guitar or bass. Not guitar synthesizers. That’s a whole other ballgame, and not one I can profess any great knowledge of. Guitar synth effects, on the other hand, are one of my particular areas of interest. Those of you who know me through Soundgas or, for that matter, last issue’s story on vintage spring reverbs (“Lords of the Springs”) will already be aware that I’m a sucker for anything exotic when it comes to old gear, and guitar synths are pretty much at the top of the tree. Why? Because to even contemplate building a box that got an unmodified electric guitar to produce sounds like those emitted by a synthesizer, using only ’70s technology, required the mind of a genius or a madman—or a combination of both. An early synth’s notes were either off or on. Creating an effects unit that would respond to the nuances of a guitarist’s playing and track subtle changes in pitch, while still remaining synth-like, required ingenious design.

Early guitar synth effects were a shortcut to almost certain financial ruin for manufacturers or buyers. The more sonically successful were complex and extremely expensive—and large. An Electronic Music Studios Synthi Hi-Fli with foot pedals makes a Mu-Tron Bi-Phase seem positively compact. As is often the case with complex, uncommon effects that few understand, when repairs were called for they often suffered at the hands of the misguided or ill-informed, or were cast aside for newer, less cumbersome devices. As technology advanced, these unwieldy behemoths fell out of favor and mostly faded into obscurity. Of the most iconic and desirable big synth pedals of the ’70s, few were made and fewer remain operational.

Okay, back to the parameters of our investigation. Most guitar synth pedals comprise a selection of individual effects—filter, fuzz/distortion, phasing, octave, ring modulation, vibrato, etc.—that are combined to enhance and mutate the original guitar signal into something more synth sounding. Some offer pitch to voltage conversion and can be used to control external synths or modular systems, but for this article I’m going to concentrate on a selection of standalone devices that embody what I consider to be the essential character traits of a successful guitar synth effect.

While I have experience with such effects, I can’t profess a mastery of their history or an encyclopedic knowledge of all the types ever produced. Attempts at historical research weren’t terribly fruitful. Even in the age of the internet there remain areas on the map of vintage guitar effects that bear the inscriptions “this area unexplored” or “here be monsters.” So this article is presented with my apologies for any omissions.