Tremolo and Vibrato, what's the difference?
The terms are often used to mean each other and they are actually not the same.
The terms VIBRATO and TREMOLO are often used interchangeably by musicians and gear manufacturers alike. Vintage Fender amplifiers were famously mislabeled with Vibrato when they actually had a Tremolo effect, and Floyd Rose bridge systems, often called a “whammy bar” are also often called a Tremolo, when what they actually do is Vibrato. What the hell?
Simply put, they are both cyclic fluctuations, but Tremolo fluctuates VOLUME and Vibrato fluctuates PITCH. There are a few blurry areas where a mix of the two things are happening, for example the Doppler effect of a rotating Leslie speaker or the complex and drippy sound of Harmonic Tremolo as used on very early guitar amplifiers.
TREMOLO
Tremolo might be the earliest standalone effect specifically for guitars. (See the Dearmond model 600 Tremolo Control from the late 40s). You would recognize it as a classic spooky rhythmic bubble to guitars in the 50’s and 60s. You might also recognize it from songs like the vocal effect on the end of Tommy James’ “Crimson & Clover” and later, the main guitar in “How Soon is Now” by The Smiths.
Early “deluxe” amplifiers would often include the effect and accomplish it by one of two popular ways. One was to have a low-frequency oscillator sweeping the bias of a tube to fluctuate the volume of the amplifier, which would give a particularly buttery and soft tremolo effect. In the mid-60s, Fender, for example, implemented a circuit which used a low-frequency oscillator to adjust the current to a light bulb that was sealed in a black plastic tube which also held a photoresistor, the fluctuating brightness of the lightbulb changing the resistance, and thus changing the volume.
In the later 60’s there were circuits developed to use transistor amplifier circuits which had their volume modulated, which gave a much choppier, square wave tremolo effect possible. This effect is sometimes referred to as Repeat Percussion.
Even in the analog world, there have been some extreme Tremolo circuits produced with multiple LFO waveforms available, variable slope to the sweep for triangle, ramp and reverse ramp waves as well as the softer, sine wave and choppy square wave tremolo. One such extreme Tremolo that I’ve built myself was based on a magazine article in the 70s that inspired Chris Carter from the early Industrial/Electronic/Experimental band Throbbing Gristle to build one, which has caused this circuit heretofore to be called the Gristleizer
(Arguably the prettiest color pedal Boss ever made, the short-lived VB-2 Vibrato)
VIBRATO
Pitch-changing vibrato differs from Tremolo as its effect is more wobbly and can induce seasickness. The topology to do the effect is totally different. With regard to guitar effects, Vibrato is usually achieved with a slight delay (say about 4ms) with no dry signal and the delay being modulated slightly, usually at a fast rate. This is how the vintage Boss VB-2 does it. You can do it with almost any digital delay with modulation.
Older vibratos, like in Magnatone amps, accomplish their jobs by using phase shift. You can get a similar effect with a mild phasor, but removing the dry signal. The Univibe guitar effect is essentially a phase shifter which uses a light source that fluctuates in brightness, altering the resistance of several optoresistors, each one attached to its own phase shift circuit, creating the unique wobbly sweep that we associate specifically with the Univibe, versus any other electronic phasor. The Univibe gives you a “chorus” and “vibrato” option, which blends the phased signal with the dry for “chorus” and bypasses the dry signal, leaving just the modulated phase shifted signal for vibrato.
HARMONIC TREMOLO
Harmonic Tremolo is one of the oldest ways to achieve a pulsing guitar effect, but it has only more recently been discussed and reproduced in the guitar pedal world. It’s one of my favorite effects as it has such a colorful and complex swirl somewhere between vibrato and tremolo. It is called Harmonic Tremolo as it splits the signal into different harmonic frequency ranges, low and high frequencies and it sweeps the volume or phase of one against the other. Sweeping the phase of the treble against the bass in such a way that there is a phase inversion between them gives such a cool effect when the frequency ranges cancel against each other. It’s hard to describe, buy you’d know it if you heard it. It’s more wobbly than tradition up down up down tremolo, much more phasor-like.
(Earthquaker Night Wire Harmonic Tremolo)
LESLIE/ROTATING SPEAKER
Originally developed for Hammond Organs, but made popular by psychedelic rock groups in the 60s who used it on their vocals and guitars, a Rotating Speaker, often called by it’s popular brand name Leslie, is usually a large box with a bottom-firing bass speaker (often 15”) which has what looks like a styrofoam cheese wheel with a section cut out and a scooped shape where it’s cut out that lets the sound of the speaker out as the wheel spins by an electric motor. On top of the cabinet is a high frequency driver that fires up into a spinning pair of funnel-shaped horns, one side letting the sound shoot out and spin around, the other side is essentially a dummy horn to counter balance the weight. Between these two spinning contraptions, usually spinning opposite directions from each other and never in sync, speed-wise, you hear the most wonderful three-dimensional sound effect as you get a tremolo (volume) effect as the sound spills out with each spin as you face the speaker cabinet. You also have the Doppler effect of the pitch bending up and down (vibrato) as it spins (the way that a siren on a police car will rise in pitch as it gets closer to you and then fall as it drives away from you). Then there are tonal effects as the sound gets bright and dark as the horn/rotor spin in front and behind the speaker cabinet. All of this splashes off the walls all around you. It’s a very hard sound to replicate with hardware, but they’ve come quite close.
ACCIDENTAL TREMOLO? THE RING MODULATOR
Tying this in somehow, is the effect called a Ring Modulator which does some strange mathematic equations with your signal but in the process, when the frequency of the effect is slow enough, it also creates a tremolo effect, whereas at higher frequencies, it creates a non-harmonious clanging bell-like tone right out of a synthesizer lab at a University in the mid-60s.
SHUT YOUR MOUTH. HOW CAN YOU SAY… I MAKE TREMOLO WITH A NOISE GATE
“How Soon is Now”, which features a pulsing rhythm guitar throughout the track, which tremolos in 16th notes, in time to the song, I’ve read, is a single guitar track re-amped through a pair of Fender amps with their tremolos on, and the engineer would get them in sync for about 20 seconds, punch in on the tape until they drift out and then reset them and punch in again, over and over. I’m not totally sure if I believe that story or not, but it’s fun to imagine. That technique seems very “Rube Goldberg” to me. I would hear similar effects on songs like “Bring on the Dancing Horses” by Echo & The Bunnymen, some songs by Cocteau Twins and later Chapterhouse. At a show at a small club by the latter, I heard the effect and noticed a noise gate effect in the rack of the guitar player and it was flashing in time with the song as the guitar was being chopped up in 16th notes. A lightbulb went off in my head and I realized that you could run any sort of pulse signal, like a metronome or drum machine, into the sidechain/trigger input of a noise gate device to tell the gate when to open and close. Feed it a 16th note pulse and set the attack and decay to soften the edges and you have a triggered tremolo effect, which if you use a drum machine, or have the drummer perform to a click track, will stay in time with the song! (The Curtain Society used this effect first on “Adrenaline” in 1994, and later, “Je Regrette Rien” in 1996. On the 1995 CD, Interia, there is a slightly embarrassing alternate dance version of the song “Kissherface” which has the effect on the guitar, except instead of a steady 16th note pulse, it follows a specific repeating rhythm with the tremolo.
These effects have come in and out of fashion over the years, but in the current times, there are many uses for these effects in all kinds of music, so many manufacturers are making these devices now. There was a time in the 90s that pretty much no one was making such pedals. Boss came out with a killer sounding stereo panning tremolo in the early 90s, at a time when no one wanted the effect, and within two years, they were discontinued and being blown out at music stores for $29.99. Those same pedals are now vintage and very sought after and fetching a lot more money than their list price when they were brand new! (Of course I have two of them!) It’s very easy to do these effects with a plugin in recording software on the computer. Its easy to draw automation to make a pulsating tremolo effect that stays in sync to the song. So many options.