Growlin’ and Howlin’: Guide to Electric Guitar Distortion
Ah, distortion! That beautiful growl that makes the electric guitar the perfect 20th and 21st century instrument — the sound of the blues colliding with noisy urban environs; the sound of the space age; the sound of anger or a wide range of other emotions, writ in howling detail; the sound of the future, stuttering to the beat of global warming and chaos, or crushed to the roar of digital feedback, zeros and ones beaten into hideous submission. Distortion can be all of those things and more.
Although there are reports of Robert Johnson practicing with a band on electric guitar just before his death – and surely the gear he was using was gnarly — the first clearly documented examples of guitar distortion we have are recordings that helped ignite rock ‘n’ roll. The first rock recording is generally acknowledged to be “Rocket 88,” a single cut by Ike Tuner’s Kings of Rhythm in 1951 (but credited to singer Jackie Brenston & His Delta Cats) with Sam Phillips engineering at Sun Records. As legend has it guitarist Willie Kizart’s amp tumbled off the roof of Ike’s car on the way to the session, causing the damage that made it growl for the microphones. That’s a great story, but plug into any low-wattage amp of the ’50s and early ’60s and turn it all the way up, and its gonna rattle and shake like a drunken snake. Certainly Muddy Waters was too practical a man to permit damage to the speakers in the amps he bought with his hard earned money, and yet his early recordings for Chess are full of lovely amp generated dirt.
Nonetheless, early distortion fiends like Link Wray, who was born on May 2, 1929, would take razor blades to their amps’ speakers to get their torn-up sound. In Wray’s case, his howling 1958 hit instrumental “Rumble” became a template for thousands of other electric guitarists looking to roar. Eventually Wray stopped that expensive practice and began using amps with gain and master volume controls, turning them both up high. He also played aggressively, literally attacking his strings, and appeared demonically possessed on stage almost until his death on November 5, 2005.
In honor of Wray, whose “Rumble” had the distinction of being the first instrumental of the rock ‘n’ roll era to be censored due to it being the sonic equivalent of a knife-fight, let’s take a look at what distortion is and how it can be created on electric guitar.
Scientifically speaking, distortion occurs when the sounds waves of a guitar are compressed and overtones are added. Both of those can happen in amplifiers when the tubes are oversaturated with power or, conversely, underpowered. There’s also the comparatively new-fangled, if we count the ’60s as being more modern than the days of Kizart’s and Wray’s sonic innovations, method of adding an effects pedal or software-based plug-in. Let’s take a quick look at some types of distortion you can generate in live playing situations, sans the sonic fringe benefits of the studio:
• Overdrive and distortion pedals: Overdrive boxes generally produce warmer and gentler distortion that actual distortion pedals. Typically these boxes use different kinds of transistors to generation their fuzzy sounds. Germanium transistors produce a more even toned-old school sound. Silicon transistors rage more. And some new-generation pedals aim to crossbreed those characteristics with hybrid silicon-germanium construction.
• Amp distortion: This involves overdriving or under-powering tubes within the amp’s circuitry. Pre-amp distortion generally is related to an amp’s gain control. Turning up gain oversaturates the pre-amp tubes with power, creating the clipping the yields distortion. Generally pre-amp distortion is more harmonically biting and brittle than power-amp distortion, which is, essentially, the classic Marshall, Mesa, etc. sound that emerged during the 1960s and early ’70s. To get good power-amp distortion, one must turn up loud. If you’ve got a gain knob on your amp, go as spare as you can to color the tone and open up the master volume, overdriving the power amp tubes to create warm distortion. Necessity — not killing audience members with volume — will likely require blending the pre-amp and power-amp distortion levels judicious to get an acceptable growl. Some amp makers have found ways to divert a portion of the signal away from the speakers. So-called power soaks and other volume attenuating boxes do the same. An amp’s output transformer can also contribute to distortion when a flood of power oversaturates it magnetically.
• Speaker distortion: If you like a distorted tone, use lower-power rated speakers, like the 25-watters Eric Clapton preferred with Cream. When the amount of power flooding a speaker reaches its maximum rating, the speaker begins to break up, or distort.