Multiphonics CV-2 Manual

Version 2.2.0

Objeq Filter

  1. Object Knob Changes the filter frequency response.
  2. Object Display Shows the object matching the current filter’s frequency response. Click on an icon to set the filter to that object.
  3. Frequency Knob Sets the filter’s root frequency.
  4. Pitch Input Calibrated for 1V/octave pitch signals.
  5. Resonance Knob Sets the filter resonance, or decay time.
  6. Audio Input Signal to be filtered (stereo) with input level trim knob.
  7. Audio Output Filtered signal (stereo) with output level trim knob.


The Objeq Filter is a modular adaptation of the filter found in AAS Objeq Delay.

It is based on the physical modeling technology AAS is renowned for and can be used with the Pulse module to create lovely physical modeling patches. It also shines as a filter in a subtractive patch, endowing a sawtooth or rectangular VCO with a resonator object’s character.


Like any filter, the Objeq Filter module expects an audio source to be connected to its In jack, and will output the filtered audio signal to its Out jack. Input and output have pairs of jacks for stereo processing. Use the left jacks in mono patches.

Because it is based on physical modeling, it can also be used to generate acoustic sounds. This is done by feeding any kind of short pulse to the input. The low-pass and band-pass outputs of the Pulse module are particularly well suited for this task.

The timbre, frequency and decay time of the Objeq filter can be adjusted with the Object, Frequency and Resonance knobs respectively. Use the Pitch input for perfect 1V/Oct pitch tracking.

You can create a very simple physical modeling patch with a single Objeq Filter module by connecting the Trig and Pitch outputs of the Keyboard to the In and Pitch inputs of Objeq Filter, and connect the output to the Left jack of the Output module.

In Depth

Object Type

The module contains a bank of 17 filters running in parallel: one low-pass filter that represents the fundamental frequency of a resonator object and up to 16 band-pass filters that represents its next 16 modes.

The relative frequency of the filters can be set to match the modes of one of the 6 preset object types by clicking on its icon in the object display. These object types are, from left to right:

  • rectangular membrane
  • drumhead
  • rigid plate
  • string
  • marimba
  • beam

It is also possible to set the object type anywhere between two objects by using the Object knob.

Modulating the Object knob will produce a nice filter sweep where the fundamental frequency doesn’t change, and higher frequencies change more quickly than lower frequencies.


The Frequency knob sets the root frequency of the object.

When using the Objeq Filter in a physical modeling patch, you can make the pitch of the object track the keyboard by connect the Pitch output of a Keyboard to the Pitch input of the Objeq Filter and double-clicking on the Frequency knob to set it to middle C (261.63 Hz).

When using the Objeq Filter as a filter in an analog patch, modulating the frequency will produce rich filter sweeps.


This controls the quality factor (or resonance) of the 17 filters.

When used as a filter in a subtractive patch, a lower resonance will have a subtle effect while a higher resonance will completely change the character of the input signal.

When used in a physical modeling patch, the Resonance knob controls the decay time of the object.

Gain Staging

Depending on how the Objeq Filter is used, its output may be softer or louder than its input. This can be compensated with the output gain knob.

Internally, the Objeq Filter has a saturation threshold to avoid extreme volume variations when processing analog oscillators and arbitrary audio signals. When using the Objeq Filter as a resonator in a physical modeling patch, you may want to lower the input gain and increase the output gain to bypass this saturation and get the full dynamic range that the module can provide.


Learn how to use the Objeq Filter by watching this tutorial (this shows the Multiphonics CV‑2 version of the module):

For an example of how to use the Objeq Filter as a physical modeling oscillator, check out the Plucked String patch in the Basics folder of the Factory collection.

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