The electric and acoustic guitar are superficially similar, but they produce sound in totally different ways. Acoustic guitars make sound from vibrations of the body, driven by the vibrating bridge, which is in turn driven by the vibrating strings. The player controls the body’s vibrations by plucking and strumming the strings. All the power of the vibrations has to come from the player’s hands.

Electric guitars generate a little sound from their bodies directly, but it’s almost inaudible. The sound you’re hearing mostly comes from the speaker cone in the amplifier, driven by current from the wall. This current is controlled by a much weaker current originating in the guitar’s magnetic pickups. As the metal strings vibrate, they agitate the pickups’ electromagnetic field, sending a fluctuating current down the cable and into the amp circuitry. Good amps respond dramatically to very subtle touches on the electric guitar’s strings that would be inaudible on an acoustic instrument.

Jimi Hendrix was one of the first guitarists to think of his instrument as a way to modulate an electrical signal first and foremost. He didn’t just pluck and strum the strings; he scraped them and swatted them and played with their tension. And he produced his most distinctive sounds by letting the amp itself vibrate his guitar’s pickups. All of these techniques are at work in his iconic performance of “The Star-Spangled Banner” at Woodstock:

Jimi’s guitar is feeding back and heavily distorted. He also throws in a little wah-wah pedal. The time is free, or as the classical musicians say, rubato – drums don’t always need to keep a steady beat. Jimi interlaces the melody notes with inharmonic screams and yowls, produced by scraping the pick against the string’s winding. He throws in a few unresolved tritones at 1:35 and some terrifying divebombing sounds at 2:00. At around 2:30 he quotes part of “Taps.” This performance has been criticized as anti-American, but Jimi said in interviews that he considered himself to be patriotic.

The first generations of electric guitarists considered feedback to be bad, a technical mishap to be avoided. Jimi discovered ways to use it as a musical expression in its own right. If the amp is loud enough, its sound can physically shake a guitar’s pickups enough to produce a current. That current gets sent to the amp, which then vibrates the pickups harder, which sends even more current to the amp, which produces even more sound. This feedback loop builds rapidly, getting louder and louder. Every beginner electric guitarist discovers feedback accidentally by leaning their guitar against their amp without turning the volume down. Feedback can also be seeded spontaneously by the slight hum produced by any electrical system that uses alternating current, or by radio waves. Cheap, poorly shielded pickups and cables make great radio antennas. I used to live on Roosevelt Island, right across the East River from a Con Ed power plant with a whole bunch of big transformers. If I didn’t face due north while playing electric guitar, I picked up all kinds of radio signals and other electromagnetic noise. It was nice for experimental music, but not so great for producing a clean sound.

Feedback is more likely, and a lot louder, when the guitar is overdriven, its signal boosted and compressed to bring out and sustain overtones that are normally inaudible. Feedback has a mystical quality, an evolving life of its own. It’s unpredictable and hard to control exactly. It would be pointless to try to score a feedback composition because there are too many variables at work; it’s an intrinsically improvisational medium. The results can be annoying or boring, or they can be transcendant. You can experience the visual equivalent by pointing a video camera at the monitor showing its own output.

Jimi was also a pioneer in his exploration of the electric guitar’s microtonal possibilities. The conventional way to control a guitar string’s pitch is to press it against the frets, changing its length. You can also bend the strings, changing both their length and tension, for more nuanced pitch intervals. Jimi’s guitars have an additional pitch control, the whammy bar, which lifts the bridge, allowing very precise control of all six strings’ tension simultaneously. The whammy bar lets you play arresting microtonal chords effortlessly. It also quickly pulls the strings out of tune, which is why in the video Jimi is continually adjusting the tuning pegs whenever his left hand is free.

The video cuts out before this point, but at Woodstock Jimi segued from “The Star Spangled Banner” into “Purple Haze.” The song is based around a distinctive chord that has come to be nicknamed the Hendrix chord.

This chord is easy to play – any beginner could learn it – but intellectually it’s extremely intense. It contains every possible interval in the western tuning system (or implies them, I count the inversions too.)

Jimi didn’t invent the Hendrix chord. It had been a distinctive device in blues and jazz since before he was born. But where Duke Ellington and Thelonious Monk used the Hendrix chord for accents and embellishments, Hendrix pushed it front and center, using it as a cornerstone for songs like Purple Haze and Foxy Lady (in different keys than the one written here.)

The electric guitar doesn’t just offer a lot of the tonal and harmonic freedom. It also leaves the player’s mouth and feet free for more expression. You can use your feet to dance, or to control stomp boxes and expression pedals. Your voice is free for singing and talking. The electric guitar is some seriously advanced interface design.

Here’s a remix/cover of “Purple Haze” by my band Revival Revival, combining Jimi with Missy Elliot, M.I.A. and Miles Davis. Enjoy:

mp3 download, ipod format download

]]> http://www.ethanhein.com/wp/2009/jimi-hendrix-electronic-musician/feed/ 5 http://www.ethanhein.com/wp/2009/wow-chicka-wah-wah/ http://www.ethanhein.com/wp/2009/wow-chicka-wah-wah/#comments Sun, 28 Jun 2009 02:33:12 +0000 Ethan http://www.ethanhein.com/wp/?p=968 Say “oooh” as in “noodle.” Then say “aaah” as in “park.” When you say “oooh” your mouth is more closed, with less resonating space and a smaller opening. This configuration blocks the higher overtones of your voice. When you say “aaah” your jaw and lips open, creating more resonating space and letting more high overtones through. Now glide from one to the other. The resulting “ooohaaaah” is the sound the wah-wah pedal is named for. By selectively filtering an electronic instrument’s overtones, the pedal can make it sound more vocal. It’s only two vowel sounds out of the dozens your mouth is capable of producing, but it’s a start toward making a more human tone.

Here’s a documentary about the wah:

Cry Baby: The Pedal That Rocks The World from Joey Tosi on Vimeo.

Combined with a guitar, the wah can do more than vowel glides. When you mute the strings and strum through a wah, you get a percussive sound ranging from “chicka chicka” to “chucka chucka.” By filtering the overtones differently, you can make other vocal sounds too. I have a digital effects unit that can make the guitar say the word “yeah” pretty convincingly. These kinds of effects give a guitarist the emotional immediacy of the voice combined with the guitar’s wide range of pitches and richness of harmonic possibility.

The guitar isn’t the only instrument you can use with a wah, and it wasn’t the first. The pedal was invented somewhat by accident when the Thomas Organ Company was developing a tone modifier for amplifiers. The first instrument they tried with it was an amplified saxophone, and the company thought they might market it for wind instruments in big bands, as an electronic version of the Harmon mute. A guitarist who worked for the company named Del Casher heard the possibilities of the new tone modifier, and he was the first person to make a recording of it in 1966.

Frank Zappa was an early adopter, and he introduced it to Jimi Hendrix, who would be the first to break it into mass consciousness with “Voodoo Child (Slight Return).” Jimi also introduced the percussive “chicka chicka” on “Little Miss Lover.” Jimi’s solos on “All Along The Watchtower” is another distinctive early adventure with wah. Plenty of other hippie rockers followed suit. George Harrison has a song called “Wah-Wah” on All Things Must Pass, named both for the pedal and for the Beatles’ whining during their final sessions together. Eric Clapton uses wah with Cream on “Tales of Brave Ulysses” and “White Room”.

Pop culturally, wah is most associated with seventies funk and soul, like on “Theme From Shaft” by Isaac Hayes, with Charles Pitts on guitar. Curtis Mayfield also had a distinctive and much-imitated wah style. From blaxploitation soundtracks it was a short jump to the porn movies that imitated them, which is why funky wah guitar is an effective comedy shorthand for getting busy. But wah doesn’t have to be seductive. Eddie Hazel of Funkadelic used it for a dark, spacey cry on “Maggot Brain.” Click here to listen to some standard wah techniques on electric guitar. The wah pedal sounds especially good on E9, the mother of all funk chords.

Hard rock and metal guitarists have found a vocabulary for wah drawing more on Hendrix and Zappa than on funk. Zappa used it less like a speech effect and more like a simple adjustable filter. He would leave it partially open to filter the high frequencies over the course of an entire song. Distortion exaggerates out the guitar’s upper harmonics and other partials, and the wah makes a great envelope controller. Jimmy Page used it on Led Zeppelin’s “Dazed and Confused,” “Whole Lotta Love,” “No Quarter” and “Custard Pie”. Slash used it with Guns N’ Roses, and Kirk Hammett leans heavily on it with Metallica.

Bassists sometimes use the wah too, especially in the funk and soul world. Michael Henderson played with one on Miles Davis’s album On the Corner. Other wah-loving bassists include Metallica’s Cliff Burton and Black Sabbath’s Geezer Butler.

Electric pianos and harpsichords operate in very much the same way as electric guitars, so it was only a matter of time before keyboard players started investigating guitar effects. Clavinet with wah sounds so much like guitar that it’s hard to tell them apart. Garth Hudson plays some pretty groovy clav with The Band on “Up On Cripple Creek”, but nothing is as funky as Stevie Wonder on “Superstition,” “Higher Ground” and his other seventies classics. Electric piano also sounds great through wah, again because of its guitar-like tone when played through an amp with distortion. Richard Wright uses it on Pink Floyd’s “Money”, and it’s on tons of Miles Davis electric recordings, especially the ones with Keith Jarrett and Chick Corea.

Any instrument that’s amplified can be played through a wah. Miles Davis got a devastating trumpet tone with wah on Live-Evil and his other darker funk records. A few saxophone players have experimented with it too, as the pedal’s original inventors intended. David Sanborn played with one on the David Bowie album Young Americans, and Dana Colley used it with Morphine.

Violin sounds great with wah. The leading practitioners are Jean-Luc Ponty in the Mahavishnu Orchestra and Boyd Tinsley in the Dave Matthews Band. Pink Floyd even tried some wah on an acoustic piano in their song “Echoes”, which also includes wah guitar made to sound like crying birds. I myself have found that wah sounds terrific on mandolin. I’ve also tried it on harmonica, but there it’s redundant since you can do the wah effect so easily with your mouth.

Wah is just one flavor of the envelope filtering you can do with a synthesizer. A lot of the craft of electronic music comes down to creative rhythmic use of the filter. A standard technique is to get a repetitive loop happening and then sloooowwwly open and close the filter over the course of a phrase or section. Since a sequencer or computer can play the actual synthesizer notes, it frees up the musician’s hands for complex multi-parameter filter control using knobs or touchscreens. We’re only at the beginning of our collective exploration of the artificial vowel glide in music.