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Guitar Modulation Pedals: Which is Right for You?

Understanding Modulation Effects for Your Guitar

Modulation effect pedals vibrate, wobble, shift and spin your guitar’s signal to create new and interesting sounds.  Unlike gain-based effect pedals, modulators change the amplitude and frequency of the waves in your guitar’s signal to create their unique sounds.  Modulators add layers and depth to the mood and texture of your guitar’s tone.  You’ll only be limited by your imagination, as some modulation pedals have a subtle effect, while others can be quite crazy.

Most modulation effect pedals work by utilizing a low-frequency oscillator (LFO) to alter the original electrical signal from your guitar.  Low-frequency oscillator circuits in the effects pedal create a control signal that has a frequency too low for people to hear.  This LFO frequency interacts with the electrical signal from your guitar creating a rhythmic pulse or sweep.  Most modulation pedals work by splitting the original electrical signal from your guitar into two signals.  One signal is left clean, while the other interacts with the LFO, before the two signals are blended back together.  The knobs on your modulation pedals work by altering the LFO.  The LFO then interacts with and alters the guitar’s signal.

As we discussed in a previous article on guitar signal chains, there are a few common rules to keep in mind when placing a modulation-type effect in your guitar’s signal chain.

  • Modulators usually work best placed after gain-type guitar effects, like a compressor or overdrive pedal.
  • Modulators typically sound best placed before echo-type guitar effects, like a delay or reverb pedal.
  • When using multiple modulation-type pedals, place the tremolo last, as it similar to echo-type effects.
  • Experiment by placing pedals in different positions within your signal chain and see what works best for you.


Modulation Pedal Categories

Modulation effects come in a few basic categories, which we’ll examine below.  Today’s guitar pedal makers also offer a huge variety in each category, ranging from simple stompboxes to complex digital processors.


Chorus Effect

If you are looking to bulk up your sound and add extra layers and texture to your tone, chorus effect pedals are a great option.  Chorus pedals seek to mimic the natural sound of multiple guitars playing together.  Most chorus effect pedals have rate, depth and level settings, which allow you to fine tune your sound.

Chorus effects work by splitting the original signal from your guitar into two separate signals.  One of these signals is left clean or unaffected, while the second signal is delayed and sometimes the pitch is also altered.  The two signals are then blended, which creates the sound of two (or more) guitars playing together, though not in perfect unison.

When working with a chorus effect, start with a softer setting and work your way up.  Too much chorus effect can become overwhelming; less can definitely be more.  If you prefer playing an acoustic guitar, chorus effects can be a great addition to your arsenal.

Check out the video below to hear the MXR Analog Chorus pedal in action.


Phase Shifting Effect

Phase shifting pedals, also known as phasers, became widely available in the 70’s with the advent of the MXR Phase 90 pedal and have been a mainstay for guitarists ever since.  Originally, phasers were designed to mimic the sound of rotating speakers.  Phasers add a layer of motion and timing to your sound and their effect can range from subtle to dramatic.  Many modern phaser pedals include multiple stages and feedback loops, for added depth and peaks.  By adjusting the speed and depth knobs, you can greatly vary the effect of a phaser pedal.

Phasers work much like chorus pedals as both split the original signal into two signals.  With the phaser, the frequency of one of the two signals is set out of phase from the other.  When blended back together, the two out of phase signals create notches or areas in the frequency band that are canceled out.  These notches create the rippling effect in your sound as the two signals move in and out of phase.

You can experiment by placing your phaser in different positions in your signal chain. For example, your sound can be greatly affected by placing a phaser either before or after your distortion pedals.

Here’s a video featuring the Golden Years Phaser from Henretta Engineering.


Flanger Effect

While similar to phasers, flangers offer an even more pronounced effect, often described as a spacey or swooshy sound.  Flangers typically also have more complex electronics, with more adjustment knobs, than phaser effects.  Some pedals even allow you to remove the auto-sweep and place the effect in a specific portion of the frequency spectrum.

Flangers split the guitar’s signal into two signals and the second signal is delayed very slightly, creating a sweeping effect when mixed back into the original clean signal.

Most often, flangers are used during specific song sections and not throughout entire songs.  Of course, this will depend on the song and how you set up your pedal, but keep in mind, flangers can have a huge impact on your sound.

Here’s the MXR Flanger in action.


Tremolo Effect

The tremolo effect was originally included in tube amplifiers.  It was also the first effect pedal to be offered in a stand-alone unit.  Tremolo effects work by varying the volume of the guitar’s signal, which creates a stuttering effect.  Tremolo pedals have timing and intensity knobs which can create sounds from a soft wave to a strong pulsating effect.  Many of today’s tremolo pedals also have flashing LED lights which help adjust the timing of the effect to match your needs.

The effect of a tremolo pedal is similar to a vibrato, but more subtle.

Listen to the Henretta Engineering Crimson Tremolo below.


Vibrato Effect

Vibrato effect pedals are similar to tremolo effects and were also initially included in many tube amplifiers.  Unlike tremolo effects, vibratos work by varying the pitch of the signal, instead of the volume.  Most pedals allow you to adjust the speed, frequency shift and depth of the vibrato.

Use caution when using a vibrato effect, as they can have an overpowering effect on your sound.  When used correctly, vibratos can add a simple, but time-honored effect to your electric our acoustic guitar.

The Dunlop Uni-Vibe pedal featured below includes a vibrato effect.


Modulation pedals are a great addition to any guitarist’s toolkit because they really do open up a world of possibilities for your guitar’s tone.  But use caution; when overdone, these effects can quickly ruin your sound.  Mix up the order of the pedals in your signal chain.  Experiment with different settings on your pedals.  Note what works and what doesn’t.  Experimenting with your sound can be one of the most enjoyable parts of playing your electric guitar, so have some fun!

Check out all the guitar effect pedals we offer!

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