What Are Envelope Filters?

by | Mar 11, 2021 | Guitars, Musical Instruments

The world of instruments is filled with surprises, and whatever is the sound requirement, you will find tools to quench your thirst.

Envelope filter pedals are one such surprise that allows you to bring new dynamics in your playing style and music-making. No matter you own a Luna, or Basswood, you are right or left handed guitarist, Envelop filters are always there to rescue your performance.

As a guitarist, you must have explored different genres. If you are currently thinking of diving into the quacky territory, then there is no better option than an envelope filter.  

But what are these envelope filters? And how this filter pedal completely immerses you into a modern kind of music-making? 


What Is An Envelope Filter?

What Are Envelope Filters?s


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In simple words, envelope filter is basically an effect pedal that is used along with guitar, bass, and keyboard to incorporate “bow wow” and “quack” sound in your playing.

Basically, this effect alters the tone that adapts to the dynamics and attacks of your guitar, keyboard, and bass playing.

So when you play hard, the tone gets more intense, and it automatically decreases when you pluck softly. The envelope effect offered by the filter is often known as auto-wah that other than blocking out specific frequencies, it often reduces the volume of certain frequencies. 


What makes it unique? Unlike other filters that are adjusted through control settings or other functions, envelope filters are manipulated by the signal strength entering into them.

It has been designed in such a way that it filters certain aspects of the audio signal produced by the instrument, and it either adds or negates high or low frequencies.

This frequency has its charm, and this is the reason numerous popular bands have used this effect in their music.


The frequency filtration process is done by a specialized circuit loaded in the envelope pedal, and the frequency of audible signals passes through while others are left out.

You must have heard of EQ pedals that come with different frequency range controls, and envelope refers to those varied EQ curves produced by your guitar, bass, or keyboard. 

The curve is ever-changing, and the filter adapts according to the notes you play. Another factor that gives them an edge over other filter pedals is the ability to use resonance to select desired frequencies in the audio signal.

So this is why the frequencies that go through the filter offer are more defined than other frequencies in the same audio signal. 

When you play notes using an envelope filter, it produces a tone that is often similar to the tone of vintage synthesizers.

Since they offer vowel type tonal quality, they are widely used in funky music genres to add to the quirky music composition.

Even though it is widely popular in funky genres, nowadays, many musicians are utilizing them for other genres to bring a new dynamic in their music.

Currently, modern jazz and rock players are incorporating this kind of pedal in their songs.

The market is filled with numerous envelope filters from different brands, and they come in all ranges when it comes to pricing.

Despite so many available options in the market, the pedals that are widely popular in the community are Electro Harmonix Q-Tron XO, Pigtronix EP2 Envelope phase, Seymour Duncan Polaron, etc.

Besides, you will also come across  Keely Neutrino,  Wampler terraform, Ashdown type 23, and Summer NAMM that also offers incredible envelope effect. 

How Does Envelope Filter Work? 

How Does Envelope Filter Works



Once you have got a good idea about envelope filters, now a question must be thinking, how do these envelope filters work?

Well, as we have mentioned earlier, the filter meticulously picks specific frequencies from the note you play. It then allows it to pass through a particular part of the audio spectrum.

But unlike others that do the filter work in a static process, it dynamically filters the frequencies as the equalizer curve is never constant when you play notes.

Since it filters out frequencies based on the intensity of your playing, so it helps you to bring out varied types of funky and quacky tunes in your music. 

Basically, it comes with a circuit where the envelope denotes the shape of the notes originating from your guitar, starting from the initial jump when you pluck till the note fades out.

So when you first pluck the string for playing a note, it automatically sparks up the filter, and the considerable spike you create is known as an attack.

However, when the signal falls from its highest peak position to the lowest one, the process is known as release. All these signal changes are assessed by a circuit in the device, which is known as the envelope follower. 

This envelope follower plays an essential part because it is responsible for customizing the effect’s quality offered by the envelope filter.

Apart from the filter, the flanger, delay,  phaser, etc. are often influenced by the envelope follower. Almost every envelope filter comes with a sensitivity knob that allows you to determine the interaction level of the pedal with the initial part of the signal generated by the note you played.

Although, the interaction level or the intensity entirely depends upon signal strength that goes into the pedal.

So in the signal chain where the guitar is connected to various other pedals before the envelope filter pedal,  the effect will be partly determined by all the devices’ volume. 

As we all know, you can customize the level of other effects pedals like choruses, flanger, phaser, delays, etc., and they will get you to continue to deliver that desired tone. However, this is not the case with envelope filters, as it doesn’t come with tonal adjustment.  

  • The quality, depth, and speed of wah-wah or voice-like effect entirely depend upon your playing style, and it delivers the tone precisely the way you want.
  • Everyone loves for its versatile working capability and assists you in creating magical tones for your songs. 
  • So when you play hard, the intensity of the interaction of signal and pedal is really high, causing the envelope filter to produce a more profound and swifter effect in your note. However, things change when you start playing gently; the effect in your note is mellow, smoother, and less intense.
  • Even though they work in a dynamic manner, you can utilize it for creating an opening and closing sound for your music.
  • The filter starts with a narrow audio frequency in the open sound setting, and then it gradually widens the spectrum so it would make a great opening sound for any kind of song.
  • The closing sound option, on the other hand, keeps the audio range wider and then gradually narrows it down to put an end. 


The Relation Between Envelope Filter and Auto Wah

The Relation Between Envelope Filter and Auto Wah




Well, the envelope filter and auto-wah are both effects that follow a similar working process of filtering out specific frequencies from the note you play through your guitar, bass, or keyboard.

However, the way they interact with the EQ curves causes a significant difference in their tonal output. In the case of auto-wahs, the tonal effects change after a certain time period and not dynamically.

Most importantly, both auto-wah and standard wah come with the option of sweeping their peak frequencies, but you can’t say the same for envelope filters.

They come with opening and closing settings so that you can get a fade-in and fade-out sound for your music. 

You might argue by saying that both envelope filters and auto wahs fall in the same segment, and both of them have the same implementation, so how can they be different?

Although the process is similar and both of them serve as an automatic effect, the way they interact with the audio signal or EQ curve is really different. 

Since wah and auto-wah come with a sweepable peak frequency, so when you press the pedal, the EQ curve shifts to a new dimension and gives you the patented voice-like tone.

But the envelope filter works differently with the EQ curve, and it changes the tone dynamically based on the intensity. 

 You will also find some automatic wahs that offer temporal effects where they modify their peak frequency according to the user’s determined speed.

However, there isn’t any envelope filter that provides the provision to change the dynamicity of their filtering or interaction process.

Everyone would agree to the fact; envelope filters are always a better option than auto wahs when it comes to solos, lead part in songs, bass part in a synthesizer, riffs, etc. 

But if you consider a broader spectrum, then auto-wah gets the edge because they can be implemented in the lead section and also for rhythm, clean and distorted tones.

You can even utilize them for playing distorted rhythms, but they aren’t really effective when you play any power chords. 


Placing The Envelope Filter At The Start of Signal Chain 

When getting a voice-like sound from your guitar is your main priority, then you should place the envelope filter at the start of the signal chain.

If you want to get the best out of your envelope filter pedal, then you have to place it at the beginner; otherwise, you will have a different tone. 

For example, if you place an envelope filter before distortion, you would get an appropriate tonal output from the filter.

But if you swap the places, then the envelope filter will give out a chaotic and harsh tonal effect, and you won’t get that old school effect in your solos or riffs.

So as a general practice, you should always place the envelope filter or any other filter at the beginning but not before the tuner pedal. 

 However, there is no strict rule for the placement, and based on the effect you want in your music, you can experiment with the filter placement.


  • While placing the filter, you should be very careful because envelope filters give out tone based on the type of signal passed through them. 
  • Many experts have suggested that you should never place this filter after a compressor because compressors modify the dynamicity of the signal and make the audio less compressed.
  • So you should be careful with the placement of the envelope filter and make sure they are at the right place. 

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