The 8 Best Filter Plugins 2021 (And 5 Best Free Filters) VST, AU, AAX

The 8 Best Filter Plugins (And 5 Best Free Filters) VST, AU, AAX |

Filters have become an integral part of music production ever since they appeared in hardware form. From the classic analog goodness to the ultra-flexible modern filters, we cover eight of the best filter plugins you could buy in 2021 and five timeless free ones in this article.

Filters find their use during mixing and mastering, sound designing, and sometimes even audio recording. Let’s look into filters in more detail:

What Is A Filter In Audio?

A filter is a plugin that removes a specific part(s) of your audio’s frequency spectrum in a way you specify. For example, a second-order high pass filter at 200Hz attenuates all the frequencies below 200Hz with a slope of 12dB per octave.

However, that’s not all a dedicated filter does. Some filter plugins have a specialized sound built into them – using saturation and slope shapes to emulate an analog filter is one of the most common types. Similarly, some offer gating and modulation features along with filters. These kinds of filters are one of the biggest timesavers, especially if you are producing electronic music.

To understand further, the regular EQ plugins we are familiar with are, in fact, collections of a variety of filters like a cut-off, notch, bandpass, and band-stop. However, when we talk about filters, we generally mean cut-offs and bandpasses with much more control, variety, and drastic manipulation.

What Does A Filter Do To Sound?

A filter manipulates the spectral quality of sound by boosting or attenuating specified frequencies. There are different types of filters, each with its specific function. However, every kind of filter certainly affects the volume/level of frequencies, usually the ones you specify.

Before we talk about the types of filters, let’s first discuss the various parts of the filters we talked about in the previous section:

High-Pass with Res |

What Is A Filter Frequency?
The filter
frequency is the position in the frequency spectrum where the filter acts. In some cases, however, such as in a band-pass filter, it’s where the filter doesn’t act. The illustration shows a high-pass filter, and the specified frequency is 500Hz.

What Is Resonance In A Filter?
The resonance is also called the “Q-Factor.” It is essentially a volume gain at the filter frequency, which can be either positive or negative. It is used to control the tone of a filter to make it more or less obvious. The picture illustrates a raised resonance, which will make the sound sharper.

What Is The Slope Of A Filter?
The slope is the distance between a filter’s active and inactive parts in a frequency spectrum. The slope is measured using decibel per octave (dB/oct). A low slope value means the spectrum will be manipulated smoothly, whereas a steep/high slope value means a harsher and more noticeable manipulation. Just like your vehicle’s speed, a higher value means a faster change from inactive to active and vice versa.

Next, let’s talk about the primary types of filters:

What Is A High-Pass Filter?

A high-pass filter is a type of filter that allows only the sounds higher than the frequency specified to be audible while turning the lower frequencies down. It is also called a low-cut filter. It is often used on instruments other than the bass to create spectral space and lessen muddiness.

High Pass |

What Is A Low-Pass Filter?

A low-pass filter is a filter that removes the sounds higher than the specified frequency while letting through everything below it. Thus, it is also called a high-cut filter. It mostly finds its use to reduce harshness or create “riser” effects by automating its frequency parameter.

Low Pass |

What Is A Band-Pass Filter?

Band Pass |

A band-pass filter allows only the specified range of frequencies to pass through and turns the rest of the spectrum down. On such a filter, adjusting the resonance/Q-factor changes the width of the band. People often use it in conjunction with send tracks to apply effects in higher precision.

What Is A Notch Filter?

Band Stop |

A notch or band-stop filter removes the assigned range of frequencies while leaving everything else untouched. We often use it with a high Q-factor to surgically remove hums and hisses in audio. However, using multiple instances and automating their frequency parameters is a famous technique in achieving creative synth sounds.

What Is A Low-Shelf Filter?

Low Shelf |

A low-shelf filter affects the volume of only those frequencies that are below the specified frequency. Producers often use it to boost or reduce the low end of a mix to shape the overall tone. However, you could also use it in place of a high-pass filter to make the effect milder.

What Is A High-Shelf Filter?

High Shelf |

The filter that only affects the volume of the sounds above the frequency you specify is a high-shelf filter. Probably the most famous use it has seen is in improving audio clarity. Occasionally, though, you might employ it to subtly reduce harsh high frequencies while keeping the audio from ending up lackluster.

What is A Peaking/bell Filter?

Peak |

A peaking filter is a filter that changes the volume targetting a specific frequency. The effect can be narrowed down to nearly a single frequency or kept wide and subtle. It’s better to strategically reduce the volume rather than increase it to prevent raising the noise-floor.


But for now, let’s have a look at the best filter plugins available today!

The 8 Best Filter Plugins 2021

1. Tonsturm SPCTRL EQ Review

More Info & Price (Trial Available)

SPCTRL EQ is the very definition of creative freedom when it comes to audio manipulation.

As the name suggests, SPCTRL EQ could be dubbed an EQ plugin instead of a filter plugin. However, it works with freeform vector curves and spectral FFT filters with a band resolution of up to 4096. Similarly, it also supports modulation, preset shapes, etc., for even quicker results.

The main graph view on the user interface is where you will be doing most of your editing. Once you enable the Transform Mode, the lower section will display parameters for scaling and shifting your filter curve. Moreover, you can also select your band resolution, frequency artifact cleaner and use a set of master cutoff filters.

Tonsturm SPCTRL EQ Review - 8 Best Filter Plugins (And 5 Best FREE Filter plugins) |

Key Features:

  • Spectral Editing
    Instead of regular plugins where you can select a certain type of filter and frequency, SPCTRL EQ allows you to shape your filters very intuitively using a freely transformable node-based curve. For example, you could create a simple linear high-pass filter or a complex step-ladder filter to sound as peculiar as you want. The resizable GUI helps make the interface convenient to use as well.
  • Curve Shape
    You can change the curvature between any two points/nodes using not one but two curve editors. People who are familiar with vector graphics software will be instantly familiar with the bezier curve shaping. This feature lets you have much more control over the curve and the slope of your filters.
  • Shape Mode
    With the Shape Mode, you can create a resizable square transformation box around your curves and shape the filters intuitively. Then, you can move the selected curves anywhere in the spectrum and scale the size of the curves on any axis. Similarly, you can also duplicate a filter shape as many times as you want inside the transformation box. And you can skewer the shapes left and right, or change the curve symmetrically. Together, they offer an incredible amount of flexibility over reshaping your filters.
  • Transform Mode
    The Transform Mode allows you to tweak the entire frequency curve in real-time. You can rescale the curve, shift it in the spectrum, and even skewer the shape. However, since you use knobs to control the transformation, resetting the parameters will undo any changes. Furthermore, you could also use the LFO modulators on the parameters to get creative with the sound.
The best filter plugin ever made?? (spctrl•eq From Tonsturm)


SPCTRL EQ is available for Windows 10 or higher and macOS 10.11 or higher, both at 64-bit only. It comes in VST 2/3, AUAAX, and RTAS formats.


This plugin is one of the most advanced filters ever created and offers an incredible amount of flexibility over the sound. What impressed us the most are the borrowed techniques from graphics designing to offer innovative ways to make the process intuitive and fun. We highly recommend you give this plugin a try.

2. Audiodamage Filterstation 2 Review

More Info & Price (Trial Available)

Filterstation 2 is a simple dual-filter plugin with a dozen filter types each.

The plugin features a large graphical interface that displays the rendition of the two filters. On the graph, dragging the filter nodes left-and-right changes their frequencies, whereas moving them up and down changes their resonance. In addition, there is a chain-link icon between the two filters to link them together as well.

Below the graph, the first two sections are dedicated to deeper filter controls. The third section shows envelope controls to control the sidechain, and the fourth is, of course, an LFO modulator.

Audiodamage Filterstation 2 Review - 8 Best Filter Plugins (And 5 Best FREE Filter plugins) |

Key Features:

  • Dual Filters
    Filterstation 2 has a total of two filters in the plugin. There are 11 filter types (+1 “none”) assignable to each. The filter types include 5 low-pass, 3 high-pass, 1 band-pass, 1 notch, and 1 peak filter. Several of the filters are emulations of hardware units, so they offer unique sounds. Unfortunately, you cannot change the slope steepness on any of the filters.
  • Sidechain
    The plugin supports both internal and external sidechaining. The Envelope section controls how the sidechain detector reacts to the input. And the “Env Amount” in the filter sections controls how much the sidechain affects the filter frequency.
  • A dedicated LFO
    There is a single LFO modulator that can control the frequency of either or both of the filters. There are 12 kinds of LFO shapes you can choose from. They involve the bread-and-butter sine, triangle, saw, pulse wave, etc., and “patterns,” which give rhythmic modulations.


Filterstation 2 is available for Windows 8.1 or higher and macOS 10.12 or higher, both 64-bit only. It comes in VST 2/3, AU, and AAX formats.


If you are looking for a simplistic filter that gets the job done quickly, then Filterstation fits the bill. However, it is worth noting that you cannot change the slope steepness in this plugin. Then again, it makes up for the limitation by offering sidechain and LFO modulation for accomplishing the most demanded creative effects in the shortest time.

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3. Cableguys FilterShaper 3 Review

More Info & Price (Trial Available)

With two powerful filters and an incredibly flexible modulation architecture, FilterShaper 3 is a strong contender among the modern options.

Each filter in this plugin has many types of filters you can choose. In addition, each filter has a drive, pan, and volume knob for even more flexibility. What’s more, almost all of these parameters are automatable. However, the biggest strength of this plugin is in the modulation department, which offers near-limitless flexibility.

Another thing worth mentioning is that the preset library is constantly being updated by a user-powered community, so creativity inspiration never runs out of this plugin. Similarly, enabling the external sidechain feature is yet another way to explore entirely new possibilities.

Cableguys FilterShaper 3 Review - 8 Best Filter Plugins (And 5 Best FREE Filter plugins) |

Key Features:

  • Variety Of Filters
    There is a big list of filter types available for you to work with. There are two types of filtering characters: clean and Salen-Key. The latter is based on the 1955 design by R. P. Sallen and E. L. Key of MIT Lincoln Lab. The filters are neatly categorized based on their character and slope steepness, ranging from 6dB/oct to 24dB/oct.
  • Filter Chain
    The two filters can be set to work in a serial chain or a parallel chain. With the parallel chain, you can easily get a multiband-style effect with many kinds of filters.
  • Numerous Possibilities
    There is a circular button next to most of the parameter knobs in this plugin. Clicking on this button opens the particular parameter’s modulation section, containing two LFOs and one envelope follower. And on top of that, each LFO has its own speed and intensity control — each with its own LFO and envelope follower, again. So in total, you have 60 LFOs and 50 envelope followers, taking the sonic possibilities beyond imagination.
  • Custom Envelope
    The envelope section of this plugin is fully editable. You can even open a larger view of the editor and design your envelope in meticulous detail. Furthermore, FilterShaper 3 comes with a square transformation tool to help you design your envelope curves even faster.
FilterShaper 3 - Cableguys : Powerful Filters


This plugin is available for Windows 7 or higher 32-bit and 64-bit or macOS 10.8 or higher 64-bit. It comes in VST 2, AU, and AAX formats.


FilterShaper 3 is an incredible frequency-sculpting plugin that can produce insanely complex modulation while keeping everything simple and understandable. All you have to do is load up some fantastic presets and try it out on various kinds of audio; you will find out why many favor this versatile beast.

4. SoundSpot FAT 2 Review

More Info & Price (Trial Available)

With an update over the free FAT plugin, SoundSpot has unveiled a beautiful and versatile analog filter plugin.

Fat 2 is a simple-looking filter plugin with four types of filters and two modulators, each dedicated to the cutoff and resonance. The filters have been designed to emulate the sound of analog filters. And each of the modulators is an envelope with free-form node-based editing.

We liked its minimalistic user interface and the analog sound most of all. The intuitive modulators also help keep this plugin understandable even for a new user.

SoundSpot FAT2 Review - 8 Best Filter Plugins (And 5 Best FREE Filter plugins) |

SoundSpot FAT2 Review - 8 Best Filter Plugins (And 5 Best FREE Filter plugins) |

Key Features:

  • 4 Filter Types
    The filter types in this plugin include low-pass, high-pass, band-pass, and FX filters. Each type contains five flavors, so you have 20 filters in total. The first three types of filters are designed to sound like analog gears, whereas the FX filter combines multiple filter types to provide peculiar sounding effects with ease.
  • Modulators
    Both the filter frequency and resonance have a modulator each. The modulator envelope has a vector curve, where you can add as many nodes as you need. Similarly, you can also enable snap-to-grid to time your curves perfectly. Changing the grid size also changes the playback rate, so you can easily create effects like side-chained ducking.
  • Presets
    There are plenty of presets with complex modulations to boost your creativity. In addition, Fat 2 can have a longer envelope length like 4 bars, so those presets are very much useable as transitional pieces. The built-in preset manager also lets you create and save your own presets.
Fat 2 Analog Filter by SoundSpot | Tutorial


Fat 2 is available for Windows 7 or higher 32-bit or 64-bit and macOS 10.12 or higher 64-bit. It comes in VST 2/3, AU, AAX, and RTAS formats.


Fans of analog filters will be overjoyed to see so many filters to choose from in this plugin. We enjoyed the great sound, fantastic resizable UI, and the intuitive envelope editor. However, the plugin does seem overpriced for its functionality. So, waiting for a sale might be the right thing to do if you enjoy this one.

5. 2nd Sense Audio Engineering Filter Review

More Info & Price (Trial Available)

This plugin is a reimagined reiteration of the classic filter shapes.

Engineering Filter focuses on being as simple and to the point as possible. It doesn’t stray around with modulations and complex sound designs. Instead, it offers the highest possible quality of the classic filter shapes with an incredible variety of slope steepness.

There is only a single filter in this plugin, but it can be a low-pass, high-pass, band-pass, or band-stop filter. There are various kinds of filter “family” or calculations, each with its unique character and sound. The graph displays a frequency spectrum, the filter’s shape, and its interaction with the audio phase.

2nd Sense Audio Engineering Filter Review - 8 Best Filter Plugins (And 5 Best FREE Filter plugins) |

Key Features:

  • Multiple Filter Types
    There are four families in the filter types: Butterworth, Chebyshev I & II, and elliptic. The first three are based on classic mathematical theories and are the basis of most hardware filter units.
  • Selectable Slope Steepness
    The filter slope starts from a simple 1st order steepness (6dB/oct), and it can be increased. However, the steepness is variable based on the type of the filter. For example, the 100th order is the highest it can go with a Butterworth low-pass filter. This feature is incredibly useful as an alias filter to ensure no sound above 20kHz is being generated/distorted.
  • Simplicity
    The best thing about this plugin is how simple it is to operate and understand. Despite being a seemingly bland plugin, its biggest advantage is the well-programmed high order filtering capacity.


Engineering Filter is available for Windows 7 or higher and macOS 10.6 or higher, 32-bit and 64-bit. It comes in VST 2, AU, and AAX formats.


As the name suggests, this plugin is highly mathematical and gives extremely precise results. The stable high-order filtering lets you brick-wall everything beyond a certain frequency with ease. However, note that it doesn’t support automation at extremely high order modes.

6. SoundToys FilterFreak 2

More Info & Price (Trial Available)

From silky-smooth filters to overdriven hardware saturation, give your audio the analog touch with this plugin.

FilterFreak 2 is a highly configurable resonant filter plug-in that combines the sounds of vintage filter units with modern versatility. It has two filter modules capable of performing low-pass, high-pass, band-pass, and notch filtering. Furthermore, it also offers “pole” switches to control the filter slope steepness.

Similarly, there are plenty of modulation sources available in this plugin, and each offers in-depth editing to create customized sweeps, sci-fi laser effects, or gated riser effects. However, it’s worth noting that only one of the available modulators can be used simultaneously, and it affects the frequency parameter alone. Although, this ensures simplicity and quick results for sure.

SoundToys FilterFreak 2 Review - 8 Best Filter Plugins (And 5 Best FREE Filter plugins) |

Key Features:

  • Analog Filters
    Each filter type in FilterFreak 2 has been carefully designed to sound and react like real, hardware analog filters. Sweeping around with the filter knob creates no unwanted artifacts, and you can select different pole values ranging from 2 to 8 in pairs. As a side note, if you aren’t familiar with the classic terminology, just multiply the pole value by six (because 1 pole equals 6dB/oct).
  • Parallel or Serial
    You can set the filters routed in either parallel mode or serial mode. And since this is an analog emulation, you will hear distinct character changes when you switch between the modes, more than a typical filter plugin. This behavior is because there is an analog circuit emulation at the end of the plugin chain as well, so the generated sound becomes saturated to give a warmer sound. However, you can turn it off if you don’t want it.
  • Rhythm Mode
    If you click on the white button on the fourth section of the plugin, you can switch to various modulators available in this plugin, and one of them is the Rhythm Mode. This mode is akin to a sophisticated LFO, but the real fun begins when you “Tweak” it to create custom rhythm patterns. It offers a grid-based curve editor, where you can create any kind of tempo-synced rhythm you want.
  • Even More Modulators
    Other than the Rhythm Mode, five more modulator types are available in the plugin: LFO, Envelope, Random, Step, and ADSR. Filterfreak 2 does not accept sidechain input for either Envelope or ADSR; instead, you will be using the main audio input and a threshold for the ADSR. However, it does accept midi inputs for midi-triggering.


FilterFreak 2 is available for Windows 7 or higher and macOS 10.10 or higher, both 64-bit only. It comes in VST 2, AU, AAX, and RTAS formats.


This plugin is a perfect blend between simplicity and complexity. You cannot do insane routings and modulation, but you can quickly create exciting rhythm patterns and much-wanted effects such as wah-wah, sweeps, stereo-modulation, etc. In addition, it also offers tweaks inside its hardware emulation to change its character. However, it’s worth noting that this plugin is on the pricier side, so we suggest trying it out first before grabbing it.

7. FabFilter Volcano 2

More Info & Price (Trial Available)

Volcano 2 is a highly capable multi-filter plugin by Fabfilter, one of the biggest contributors in the modern audio plugins market.

At the heart of the plugin are four filters, each with three types: high-pass, low-pass, and band-pass. In addition, you can choose from three slope steepness options ranging from 12dB/oct to 48db/oct. Each filter also has over ten characters like gentle or hard, which colors your audio as the name suggests.

Moreover, when you combine the filters with the modulators and routing features, Volcano 2 shows its true capabilities. There are four kinds of modulators in this plugin: XLFO, Envelope Follower, Envelope Generator, and Midi Source. You can add each kind as many as you require and use drag-and-drop to assign the modulator to a certain parameter. Similarly, you can also change the routing between stereo, left/right channel, and mid/side separated.

FabFilter Volcano 2 Review - 8 Best Filter Plugins (And 5 Best FREE Filter plugins) |

Key Features:

  • Modular Interface
    Volcano 2 sports what-you-use-is-what-you-see GUI, so if you aren’t using any modulators, you won’t see any. You could even turn off the modulation page entirely. As you increase the number of filters and modulators, you will see their interfaces populating your plugin. You can resize the GUI to make editing easier too. Similarly, the filter display also lets you change the filter frequency and resonance by simply dragging the nodes on the graph.
  • Fantastic Sound
    The filters in this plugin are very smooth-sounding and have 11 unique character traits to color your sounds. You can also change the panning and add a delay (latency) to individual filters to get esoteric sounds.
  • Four Modulators
    On the modulation page, you can add any number of modulators you need. And assigning a modulator is as easy as drag-and-drop. There are four kinds of modulators:

    • The XLFO lets you create custom LFO waveforms and also lets you synchronize the speed to your DAW.
    • The Envelope Generator is a regular ADSR that is triggered by either audio or midi.
    • The Envelope Follower will follow the loudness of your internal sidechain or external input.
    • The Midi Source transforms any midi data sent into the plugin into a modulation.
  • Routing
    This plugin lets you route the four available filters in almost every way possible. There are 3 basic routing configurations: Stereo, L/R, or M/S. Volcano 2 displays all the routing possibilities for each configuration depending on the number of filters you employ.
3 Crazy Filter Sound Design Tricks – FabFilter Volcano 2 Filter Tutorial


This plugin is available for Windows Vista or higher 32-bit or 64-bit and macOS 10.10 or higher 64-bit. It comes in VST 2/3, AU, AAX, and RTAS formats.


It’s almost guaranteed that the plugin will be of high quality when it comes to Fabfilter, and the Volcano 2 is no different. There are almost 300 presets for you to explore, and the incredible amount of flexibility it offers is highly praiseworthy. However, the rather unconventional approach at the UI may be a love-or-hate feature for many people.

8. Waves Metafilter

More Info & Price (Trial Available)

Waves MetaFilter is a sound-shaping filter plugin with their Virtual Voltage technology for analog sound.

There is a single filter module in this plugin. And it is designed to deliver the warmth and fatness of classic analog filters while being paired with modern control and flexibility. You can modulate the filter’s cutoff, resonance, and delay time using three separate modulators.

The filter section has low-pass, high-pass, band-pass, comb, and gain options. The gain option could be used to get gating, stuttering, and ducking effects when paired with the sequencer. It also offers sound design tools like a stereo enhancer, a saturator, and a resampler.

Waves Metafilter Review - 8 Best Filter Plugins (And 5 Best FREE Filter plugins) |

Key Features:

  • Analog Sounds
    MetaFilter uses Waves’ Virtual Voltage technology to emulate analog hardware units. This feature gives the entire plugin a very earthy sound. The plugin also features a Drive parameter to add further to the analog vibe, which overdrives the filter unit to give saturation to your audio.
  • 3 Modulators
    Meta Filter has an LFO, a step sequencer, and an envelope follower. The step sequencer can have up to 16 steps, as shown in the picture. And the envelope follower can either react to the main audio input or a sidechain input. Setting it to react to the main audio input is a great way to get a quick and easy “wah-wah” effect.
  • A Delay Unit
    This filter plugin also sports a delay unit. It can be synced to your tempo or not, and you can also offset the right output channel to give it an enveloping sound. There’s an “Analog” button on the left side of the delay section, making the delay time parameter smoother. So, you can then automate it without artifacts. The Route button switches the delay from being routed before the filter or set in a feedback loop.
Waves MetaFilter Plugin Tutorial


This plugin is available for Windows 10 or higher and macOS 10.13.6 or higher, both 64-bit only. It comes in VST 2/3, AU, AAX, and RTAS formats.


Built around a multimode filter with extensive modulation possibilities, the MetaFilter is a convenient plugin that offers plenty of features to get great-sounding results quickly. Using a rhythmic audio clip with the comb filter set to follow the audio signal, for example, is a great way to get complex results with fewer tweaks.

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The 5 Best FREE Filter Plugins 2021

1. Noiiz Filter By Noizz

More Info & Download

Simplicity at its best.

The Noiize Filter is a unique filter plugin designed to emulate analog filters. It has four types of filters: high-pass, low-pass, band-pass, and notch. However, the most interesting part we found in this plugin is its noise generator. The noise it generates is designed to mold with your input audio to create interesting effects.

Noiiz Filter By Noizz Review - 5 Best FREE Filter plugins |

Key Features:

  • Analog Filters
    There are four types of filters and multiple flavors under each type to reach nine kinds of filters in this plugin. Each filter is designed to emulate the analog shape and character, so the ending result is warm and silky smooth.
  • Noise
    The noise generator has a huge library of noises you can choose from. It includes unconventional noises like rain to highly-demanded ones like vinyl crackles. So, you could even use this plugin to get Lo-Fi sounds. There is a dedicated knob to control the noise level, so you could have it turned off or as loud as you need. Similarly, you can also change the pitch of the noise to create interesting “riser” effects.
  • Drive
    Since the plugin is an analog emulation, some warm-sounding saturation is crucial as a cherry on top. And Noiize Filter delivers it by offering a convincing overdriven circuit that works with the filter resonance to give beautiful distortion.
Noiiz Filter - FREE new plugin for music producers!


It is available for Windows 7 or higher and macOS 10.9 or higher, 64-bit. It comes in VST 2, AU, and AAX formats.


We often need a simple filter plugin that does the job, and that’s when the Noiize Filter works best. You might also like its noise feature to add some background texture to your audio. However, it’s worth mentioning that despite being free, you need to become a free member of Noiize to download this plugin.

2. BPB Dirty Filter

More Info & Download

Utilize the BPB Dirty Filter to provide subtle color or crush the audio into fragments.

Bedroom Producers Blog’s BPB Dirty Filter is a freeware plugin with two cutoff filters and replicated analog tube circuits. For the creative sound designers, though, as good as the filters themselves are, the dirty distortion it offers is what opens a world of sonic explorations.

BPB Dirty Filter Review - 5 Best FREE Filter plugins |

Key Features:

  • Versatile
    It is a great utility for cleaning up your audio, as it combines a high-pass and a low-pass filter. Both filters feature a frequency range of 20 Hz to 20 kHz with selectable filter slopes. The plugin also has a Mix knob and an output volume control for easy gain staging in your DAW.
  • It Plays Dirty
    BPB Dirty Filter is a transparent filter plugin when the Drive knob is set to zero. It’s ideal for reducing high-frequency noise or removing low-frequency hum in this mode. However, when the Drive knob is turned up, BPB Dirty Filter becomes one of the harshest distortion plugins available. This tube distortion is probably what you will want this plugin the most for. Just select a range of frequencies and crank up the drive.
  • Lightweight
    The BPB Dirty Filter barely makes any impact on a moderately powerful CPU, so you will have no problem loading as many of this plugin as you need. We recommend trying its distortion out on multiple frequency ranges and setting the Mix knob to taste.
Dirty Filter FREE Filter/Distortion VST Plugin By Bedroom Producer Blog Review And Demo


This plugin is available for Windows and macOS at both 32-bit and 64-bit. It comes in VST 2/3, AU, and AAX formats.


While any old EQ will let you dial in a couple of cutoff filters, the BPB Dirty Filter offers a slope steepness as high as 48dB/oct, which is difficult to come by in regular stock plugins. Similarly, the tube distortion has its unique character and deserves a try from anyone interested in sound designing.

3. HY-Filter3

More Info & Download

The free version of HY-Filter3 is a creative filter plugin with two unconventional kinds of filtering.

Instead of an individual cutoff or band filter, HY-Filter3 Free offers two types of filters, both of which use a mix of multiple filtering techniques. The plugin also has a saturator, offset for skewering the band, a three-band EQ, and an LFO modulator. Together, they form a powerful sound design tool.

HY-Filter3 Free Review - 5 Best FREE Filter plugins |

Key Features:

  • Type I: SVF
    The ‘state variable filter’ allows you to set a filter type between low-pass, band-pass, and high-pass as you want. For example, setting the dial somewhere between LP and BP will give you some high frequencies along with the full sound of the low-pass filter. This technique is incredibly useful to create a milder effect when it comes to filtering your audio.
  • Type II: Reso
    The Reso type is based on the MAM RS3 Resonator. It uses a complex combination of three band-pass filters and an LFO modulator to give sweeping sound effects. There are three kinds of Reso filters to choose from in this plugin, and you can also set the band-pass filters to any frequencies you want.
  • Modulation
    The HY-Filter2 Free has a single LFO modulator, which can modulate the filter frequency. There are multiple waveforms to choose from, and you can also sync the LFO to your DAW. Another thing worth noting is the Randomizer, which can either reset the displayed parameters or randomize their value to create interesting effects.
HY-Filter3 Walkthrough - 5 Powerful Filters


This plugin is available for Windows 7 or higher 32-bit or 64-bit and macOS 10.11 or higher 64-bit.


The HY-Filter3 Free is a feature-rich freeware that lets you get interesting sounds in a short time. However, for simple filtering tasks such as removing a low-frequency hum, this plugin could be overkill. So instead, what it shines at is sculpting synth sounds to create sweeping soundscapes or distorted garble.

4. Phuturetone Philteroid

More Info & Download

Turn any boring sound into something interesting with this filter plus sonic modulator combo.

Philteroid is a dual resonant filter effect that sounds fantastic, especially on rhythmic sounds, paired with its AM, FM, and saturation features. There are five types of filters: low-pass, high-pass, band-pass, notch, and all-pass. Add the modulations, and it can turn a basic sound into one with unique character and fascinating textures, in addition to pure filtering.

There isn’t a dedicated modulator to automate the filter section. However, almost every knob is automatable, so you can use your DAW’s envelopes or modulators to create impressive effects in no time. In addition, the filters are quite smooth-sounding even when paired with the input drive.

Phuturetone Philteroid Review - 5 Best FREE Filter plugins |

Key Features:

  • Amplitube Modulation
    The AM feature can act on the internal audio generated by the filters. However, you can control how much AM is applied to your audio using the envelope follower with the sidechain feature. Similarly, you could also use external audio to apply AM on your main audio to create rich sounds. There are also ADSR envelopes and midi-triggering to further help you in targeting your AM.
  • Frequency Modulation
    With the FM feature, filters can be synced in eleven preselected harmonic offsets in the filter frequencies and modulated internally by the generated audio. However, like with AM, you could also use external audio to apply FM. ADSR envelopes and midi-triggering are also available. Although, the midi input also acts as the FM note tracker.
  • 12 inputs/outputs
    There are twelve input and output ports, but they aren’t filtered. Instead, they are used for routing and modulation. It’s worth noting the filters themselves are mono.


Philteroid is available for Windows 7 or higher at 32-bit only. It comes in VST 2 format.


Although the lack of a 64-bit version and the difficult interface makes it a bit of a miss, the amount of creative sounds you could create using this plugin and a couple of audio signals is incredible.  If you are looking for a quick and frugal way to get gritty-sounding AM and FM, you should give this plugin an honest try.

5. Audiomodern Filterstep

More Info & Download

Filterstep is a filter plugin designed for getting intricate rhythmic sounds.

There is a single filter in this plugin, and you can select from a high-pass, a band-pass, and a low-pass filter. The lower section is the sequencer that lets you create patterns for your filter’s frequency parameter. In contrast, the upper section lets you control the sequencer’s properties, direction, randomize the sequencer, and so on.

The first slider on the left lets you adjust the filter’s smoothness when changing the frequency with the sequencer. And the second one adjusts the range of the sequencer. Finally, the third one lets you adjust the filter’s resonance. There is a clean bypass button on the left that is automatable too.

Audiomodern Filterstep Review - 5 Best FREE Filter plugins |

Key Features:

  • Sequencer
    The lower section of the plugin is an easy-to-use sequencer where you can adjust the value of the frequency using the steps. You could also use the dice button to randomize the sequencer and get complicated sounds. The sequencer lets you set the rate of playback, number of steps, and sync or not sync to your DAW. The key icon lets you keep certain steps locked while exploring random variations on the rest of the sequencer.
  • Multi-Pattern
    At the bottom of the pattern, you’ll find a row of buttons labeled presets. Each can hold a new pattern for your sequencer, so switching the rhythm style in the middle of your song is as easy as changing the pattern. Once you modify your sequencer values, just click on an empty slot, and the new sequence gets stored in that slot.
  • Infinite Generation
    Filterstep can create an infinite number of sequences. You can also tell it to generate a certain number of patterns and repeat itself. If you just want a textural background in your project, try using many regenerations to achieve unending texture variations.
FILTERSTEP by Audiomodern - Walkthrough


This plugin is available for Windows 7 or higher and macOS 10.12 or higher, 32-bit and 64-bit. It comes in VST 2/3, AU, AAX, and iOS formats.


Filterstep is a great plugin to get rhythmic sounds. You could use it to achieve predictable rhythms like a gated synth pad and bass or get random sonic movements with the randomizer. We would highly recommend keeping this phenomenal plugin in your arsenal as it’s truly one-of-a-kind.

Related Readings:

The 7 Best Vibrato Plugins To Add Some Life

7 Best Vari-Mu Compressor Plugins For Busses And Full Mixes

Top 5 Audio Metering Plugins To See The Insides Of Your Audio

Top 7 Multiband Compressor Plugins 2021

7 Best Exciter Plugins – Make Those Vocals Stand Out

Top 6 Limiter Plugins 2021 (And 4 Best Free Limiters)

Boring Vocals? Here’s What’s Missing – The 11 Best Vocoder & Vocal Processors 

Bonus Plugin

NoiseAsh Action Filter

More Info & Price (Trial Available)

With a user-friendly UI and rapid, deeply adjustable controls, Action Filter is designed to meet your demands whenever you reach for any type of filter.

The plugin has two filters set in a serial chain. The filters have over a dozen filter types each, and some of them are designed to emulate analog models. In addition, each filter can have a modulator to automate its frequency and resonance parameters.

The modulation option includes three kinds of modulators: a custom envelope, an LFO, and a step sequencer. Each modulator can be set to sync with your DAW or run freely. Finally, there’s a saturation stage at the end of the chain to give your audio a gritty tone.

NoiseAsh Action Filter Review - 8 Best Filter Plugins (And 5 Best FREE Filter plugins) |

Key Features:

  • Multimode Filters
    Each of the two filters has 13 types. There are six low-pass filters, three high-pass filters, a band-pass, a notch, an all-pass, and a ring mod. Being a serial chain, you could use the two filters to get even more intricate sounds out of the plugin without spending much time.
  • Advanced Modulation Engine
    Acton Filter has a modulator for each filter module, including an LFO with 5 waveforms, a custom envelope, and a 32-bar step sequencer for endless possibilities. In addition, the custom envelope editor can be zoomed in and supports mouse modifiers for easy editing.
  • Analog Sound
    There is no denying that analog units have their own unique sounds. And while plenty of plugin developers have replicated the analog filter shapes, only a few include an emulation of a vintage saturation unit. Action Filter employs a warm, analog saturator at the end of the effect chain, which could be used to add some warmth to your audio or to cause sonic destruction.
Action Filter Plugin - Teaser & Overview


This plugin is available for Windows 7 or higher 32-bit or 64-bit and macOS 10.9.5 or higher 64-bit. It comes in VST 2, AU, and AAX versions.


Despite the simplistic look, Action Filter packs quite a punch, especially considering the price when it’s on sale. This plugin should be highly satisfying if you want both a warm, analog sound and digital modulation magic.


Filters play one of the most important roles in creating good mixes. Sure, modern equalizers are capable enough to replace the classic filters. But as we can see, modern filters offer far more than a universal EQ. Extensive modulations, impressive slope steepness, and sometimes even spectral editing features make filters a gateway to a new realm of sonic possibilities.

If you are interested in editing your frequency spectrum in meticulous detail or just getting the maximum freedom possible, the Tonsturm SPCTRL EQ is an unbeatable choice. Its curve-based spectral editing is unmatched by all.

Similarly, if you are a fan of analog hardware units, SoundSpot Audio Fat 2 and Waves MetaFilter are excellent choices, each with its original method of emulating hardware nuances. NoiseAsh Action Filter is a fresh, convenient option as well.

The freeware market also has a lot to offer – even if you own proprietary plugins, AudioModern Filterstep’s rhythm machine and Phuturetone Philteroid’s FM/AM are well worth checking out. Not to mention the dirty and gritty growls of the BPB Dirty Filter are unlike anything else available.

There is much you can explore. We hope this list proved helpful in helping you learn the basics of filters and deciding which ones you want to try out next.

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