ASVF-212 Analog State Variable Filter

    A State-Variable Filter is an active filter that uses multiple feedback techniques to produce filter responses (LowPass, BandPass and HighPass) from a single filter with user selection. Classical SVF filters include controls for Filter Frequency, Filter Q and Gain. With the ASVF-212, we included deep LFO control for the device’s parameters. A variety of textures and horizons of modulation morphing can be created by routing destinations such as Filter Freq, Filter Q, Low-High Filter Response, and Notch-Peak FIlter Response. The ASVF-212 has an additional Notch Filter (Band Stop filter) and Peak Filter (BandPass filter).
The device can also take advantage of Envelope Follower tricks with modulation destinations for FIlter Freq, Filter Q, Low-High Filter Response, and Notch-Peak Filter Response with a few Envelope Follower detection modes.
What makes the ASVF-212 different from a typical SVF filter? It is a Stereo filter-bank (LP, HP, BP, Notch, Peak filters) with deep LFO and Env. Follower modulation. The ASVF-212 includes a Blend knob (Dry/Wet mixture of incoming and processed signals) to create more interesting and creative effects. The user can use the included hard clipped Limiter to control the final signal by adjusting the necessary Gain and Pre-Gain (unprocessed) levels.


Filter Frequency – Cuftoff Frequency of HighPass, BandPass and LowPass filters
Filter Q – Strength of resonant peak at cutoff frequency
Low-High Freq Response – Fade between LowPass and HighPass response
Notch-Peak Freq Response – Fade between Notch/BandStop and Peak/BandPass response

Notch Filter (Band Stop)
A notch filter is basically the opposite of a BandPass filter, it rejects, or stops, a specific band of frequencies. A Notch filter is also known as a “Band Stop Filter”. It works as summing of HighPass and LowPass output responses.

Peak Filter (Band Pass)

A Peak filter is a frequency filter that passes a narrow band of frequencies and stops all other frequencies. This is a very narrow BandPass filter and the opposite of a Notch filter. For example, peak filters are used in WahWah effects.


Wave – LFO Waveforms: Sqr, Sine, Tri, Saw, Uniform, FlatMid, EarlyComb, Essence
Destination – LFO destination: Filter Freq, Filter Q, Low/High Filter Response, Notch/Peak Filter Response
Modulation Way – Increase / Reduce the destination mod parameter
Mod Index – Ramping LFO steps. 0% switches from one value to the next
Rate – LFO Rate (mode in sync with Step grid or Time in seconds)
Random Amt – Scale each step of LFO by a random amount
Sync Mode – Set the LFO rate in steps per beat or steps per second
LFO Amt – Amount of the LFO modulation
Retrigger – Restart LFO steps after pauses (sync = Sec), and when Bar beat changed (sync = Beats)
Rate Affect – How much the value affects the LFO Rate (if Env.Follower is enabled – how it affects the LFO Rate)
Drift Contour – How much the value affects the LFO Wave (if Env.Follower is enabled – how it affects the LFO Wave). Change the waveform from hard to soft curve.

Envelope Follower

Mode – Envelope detection modes:
LIN: Linear voltage measurement up to the threshold level;
LOG: Logarithmic dB measurement above the threshold level;
GATE: Switch off and on as the signal level passes the threshold
LIN: Audio level for full modulation;
LOG: Audio level for no modulation;
GATE: switching Threshold.
Attack – Rise time when the audio level increases, or the gate opens
Release – Fall time when the audio level decreases, or the gate closes
Destination – Off, Filter Frequency, Filter Q, Low/High and Notch/Peak frequency response


Clip Limiter – Limiter on/off. CPU safety hard clipping limiter
Release – Recovery time
Pre-Gain – Gain of incoming signal
Gain – Output Level Gain


Bypass / On / Off – Standard fader with 3 modes: Bypass effect, On Effect, Off Effect
Patch Browser – Open, Browse and Save your own patches
Blend – Blend Dry/Wet functional of incoming and processed signals
Soft Bypass – Bypass with fades of Vocoder effect activity (without glitches)

  $25.00 – Go to the ReasonStudios Shop

Download ASVF-212 Manual [PDF]


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