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Guitar Tools
That Throbbing Feeling: Pro Tools Tremolo Tricks
By Joe Gore

How do I love thee, tremolo? Let me count the ways.

You’re primitive. You’re rhythmic. You’re spooky. You’re sexy. You make bland guitar tracks sound a lot cooler than they actually are.

You’re also misnamed. The tremolo I love is a rapid pulsation of volume, an effect found on some ’50s and ’60s amps and replicated by countless stompboxes and effect modelers. But in official music-theory speak, tremolo means the rapid repetition of a single note or chord, like a speedily plucked mandolin. To further cloud matters, some amps (old Fenders, for example) refer to the effect as vibrato. That’s another misnomer, since vibrato refers to a small, rapid fluctuation in pitch, not volume. Only a few vintage amps, such as various Magnatones and the Roland JC-120, had actual vibrato.

"Call it what you will,
tremolo is the coolest guitar
effect in the universe."
But call it what you will, tremolo is the coolest guitar effect in the universe. So let’s look at some high-tech ways to create the ultimate low-tech effect.

DIY Wobble
Before we talk about generating tremolo with plug-ins, let’s prepare some trem tracks from scratch using volume automation in Pro Tools. Download a sample session ( PC | Mac), or work with your own guitar track. My sample session includes a few bars of guitar and a stereo rhythm section track. I’ve also created MP3s of the audio examples discussed here.


Figure 1: There’s a complete lack of volume automation on this guitar track.
Figure 2: Avoid extreme volume fluctuations like this when creating automation.
Figure 3: A moderate volume range is more effective and won’t hurt your ears.
Figure 4: A triangle waveform approximates the sound of a traditional amp tremolo.
Solo the guitar track and have a listen. It was recorded through an amp simulator, but with no trem or other effects. Now let’s make it shake: Switch to the track volume view by shift-clicking on the “Waveform” label. You’ll see the current volume automation — that is, none.

Let’s draw in some volume automation. Click-hold on the Pencil tool and select the square-wave option from the drop-down menu. Next, draw over the waveform, but don’t press Play yet! (I mean it! Don’t make me come over there!) It’s easy to write automation that will shred your speakers. Hitting Undo between each edit, try click-dragging the pencil across the waveform, getting a feel for how it behaves. Your initial click sets the median volume. The amount you drag up or down sets the degree of volume fluctuation. Note how the modulation defaults to the grid’s rhythmic value — in this case, sixteenth notes.

Unless you have your speakers turned way, way down, don’t play anything like I’ve illustrated in figure 2. Instead, try something like the automation in figure 3.

The automation shown in figure 3 probably won’t destroy your speakers, but it sounds like crap. The hard on and off is so extreme that there’s a crackle with each modulation. So let’s make some changes. Remove the automation, click-hold on the Pencil tool again, and select the triangle waveform option. Redraw the volume automation and have a listen. Go ahead and get extreme — without the hard on/off of the square wave, you’re not likely to do any damage. For an approximation of traditional amp trem, try something like figure 4.

Check out the next example. Sounds better, huh?

Remember, you don’t have to use even subdivisions like eighth notes or sixteenth notes. For example, try a dotted-eighth-note rhythm: Click-hold on the downward arrowhead in the Grid field, select “1/8th note” and then “dotted,” and redraw the automation with the Pencil tool. Syncopated rhythms like this can sound nice and groovy against steady rhythms, as heard here. That, after all, is the essence of tremolo: It’s an extra rhythm layer that can add groove, complexity, and mystery to a track.

Aping Amps
Okay, it sounds better, but it probably won’t cut as much as a classic analog amp trem. For one thing, amp tremolo is a tube-driven process that subtly alters the tone of the guitar. Fortunately, the latest amp and effect simulators do an excellent job of mimicking these subtleties.

Line 6’s Amp Farm, IK Multimedia’s AmpliTube 2, and Native Instruments’ Guitar Rig faithfully replicate the response of vintage units. In some cases, you can choose between a mono effect with the modulation waveform controlling overall volume, and panning, where one channel gets louder while the other gets softer. It can be a cool, druggy effect, as heard here, which was created with Guitar Rig.

Figure 5: McDSP’s Chrome Tone amp simulator
does basic tremolo and much more.
Other amp plug-ins offer more than vintage-style trem. Take the tremolo function in McDSP’s Chrome Tone amp simulator: Chrome Tone does nice, simple trems, but adds such options as a choice of modulation waveforms, dynamics-dependent modulation, and complex sync options.

The most over-the top trem I’ve encountered is Sound Toys’ Tremolator. It boasts advanced groove options (including variable swing and accent), super-hip presets, and an amp stage with wicked faux-analog distortion. For hardcore trem fetishists, Tremolator is it.

Get Off the Grid
Another factor in faking amp trem is irregularity. Most of the classic trem effects on record are almost, but not quite, in sync. Take the best-known trem effect of the ’80s: the pulsating, Bo Diddley–influenced rhythm guitars on the Smith’s “How Soon Is Now?” It grooves like a monster, but it’s far from perfectly synchronized. (No surprise, since guitarist Johnny Marr manually aligned the tempo simply by nudging the rate knobs on his Fender Twin Reverbs.) The point: Just because modern plug-ins let you create perfect time-modulation effects doesn’t mean you should do it that way!

One great way to create that “almost, but not quite” effect is by using a trem effect with a tap-tempo option. In the next example, I tried to tap in the exact tempo by clicking the tap-tempo button in Tremolator. I wound up with 109 bpm, as opposed to the actual session tempo of 108 bpm. It sounds cooler to my ear when it’s a little off. (I also dialed in extra amp-fry by selecting Tremolator’s “Crunch” option, one of several output overdrive modes.)

You can also get fine tap-tempo trem effects using hardware amp simulators such as M-Audio’s Black Box (an amp/effects modeler that doubles as a Pro Tools M-Powered interface), and many of Line 6’s amp and effect modelers, including the PODxt, PODxt Live, and the MM4 Modulation Modeler. Line 6 also makes the Tap Tremolo, a tap-tempo stompbox.

Combining Trem with Other Effects
Figure 6: Placing tremolo last in your effects chain
highlights the trem flavor.
Tremolo almost always sounds great with lo-fi delay and reverb — they just naturally go together, like swamp water and malaria. But whether you’re working with software or hardware, the order of the effects chain has a huge influence on your results.

Consider these factors: In most trem-equipped analog amps, tremolo is the last stage before the output. Also, as a rule of thumb, an effect tends to be more strongly flavored the later it occurs in the effect chain. So if you’re going for a bold tremolo effect, you’ll probably want to place the trem downstream from delays, spring reverbs, and the like. In the next audio example, I placed Line 6’s Echo Farm plug-in in front of Tremolator. I dialed in a dotted-eighth-note echo rhythm with no regeneration — just a single slap. Single-slap delay before tremolo is a fantastic effect. The trem obscures the delay — you’re less likely to perceive a discrete echo than a surreal and spooky ambience.

Figure 6, taken from the stompbox view in IK Multimedia’s AmpliTube 2, shows one effective routing scheme, with distortion followed by delay followed by trem.

Jurassic Tremolo
Of course, you can always make tremolo the old fashioned way — with an amp. Besides simply tracking guitars through amps, you can also pipe pre-recorded Pro Tools tracks through them with the assistance of a reverse direct box such as the John Cuniberti Re-Amp or Radial X-Amp.

Some of the most sought-after vintage amps, such as Fender Deluxes and Twins and Vox AC15s and AC30s, have super-cool tremolo sounds. But an amp doesn’t have to be a collectible to give great trem. (For example, the surprisingly good-sounding Vox Pathfinder, a solid-state practice amp, sells for a little over $100.)

The two most popular amp trem flavors are the opto-trem circuit found on mid-’60s Fenders and the bias-based systems of older Fender and Vox amps. The more familiar opto sound is sweet and clear, while the Vox sound is fat and cushy, with the barest hint of phase shifting. A third trem sound, the true vibrato found on ’60s Magnatones, has a fanatical cult following. It’s difficult to duplicate with modern gear, though I’ve managed to get very close with an Electro-Harmonix Wiggler pedal. (If you’re curious, email me and I’ll share the tone recipe.)

"An amp doesn’t have
to be a collectible to
give great trem."
Finally, let me add a few words about some of my fave tremolo stompboxes, besides the aforementioned Line 6 MM4 and Electro-Harmonix Wiggler: The Boss TR-2 is a simple, sensibly priced non-boutique option that delivers a fine Fender-style trem. The Guyatone VT-X is an AC-powered, tube-equipped monster. It’s loud and bold and packs a vast modulation range. And lately I’ve been hyperventilating over the Cusack Tap-A-Whirl. It’s a true analog tremolo that manages to incorporate many features of digital trems. It’s the first analog trem with tap-tempo, and it offers a choice of eight modulating waveforms. There’s a Leslie rotating speaker-style “brake” function that slows the modulation when you hold down the tempo switch. Yum.

If all else fails, there’s one last-resort trem tip: Flick your volume knob or fader back and forth real fast.


Joe Gore (joe@joegore.com) has worked with Tom Waits, PJ Harvey, Tracy Chapman, Courtney Love, the Eels, and many others. He writes extensively about music and audio and has interviewed hundreds of the world’s leading players, composers, producers, and technicians. Joe’s latest collaboration is Clubbo
(www.clubbo.com), a sprawling “music fiction” project.