Audio Para EQ CHOP
The Audio Para EQ CHOP (parametric equalizer) applies up to 3 parametric filters to the incoming sound. The three filters are in series, where internally, the second filter takes its input from the output of the first filter, and so on.
It is called parametric because each filter has 3 controls - center frequency, bandwidth and boost, which in the old days, was more than usual analog filters.
Each filter has a center frequency (the Frequency parameter) where the filter will have the most effect, and a bandwidth which is roughly expressed in octaves, and is typically 3 or 4. The Boost parameter, when it is greater than 0, will make louder the audio around the center frequency. When boost is less than 0, it will make the audio quieter around the center frequency. Boost is in decibels (dB) where 0 dB has no effect.
You can best hear the effects of the Audio Para EQ CHOP by passing it rich-spectrum music. The Audio Para EQ CHOP is implemented with three 4-pole filters internally.
Input 2-4: See Frequency Modulation Channels, and the Scope parameter.
The Audio Para EQ CHOP is implemented as three 4-pole filters in series.
Parameters - Parametric EQ Page
/units - How frequency is expressed:
- Logarithmic - The filter cutoff frequency can be expressed as a power-of-10. See Frequency (Hz = 10**val) below.
- Frequency - The filter cutoff frequency can be expressed in Hz.
/enableeq1 - When off, it passes the sound through the first equalizer unchanged.
Boost (dB) EQ1
/boost1 - When boost is greater than 0, it will make louder the audio around the center frequency. When boost is less than 0, it will make the audio quieter around the center frequency. Boost is in decibels (dB) where 0 dB has no effect.
Frequency (Hz = 10**val) EQ1
/frequencylog1 - The frequency is expressed in power-of-10, where value 0 translates to 1 Hz (10**0), value 1 is 10 Hz (10**1), value 2 is 100 Hz (10**2), value 3 is 1000 Hz, value 4 is 10,000 Hz, value 4.5 is 31,623 Hz. The parameter in this form gives more meaningful range in relation to human hearing, as increasing the parameter by 1 raises the frequency by about 3 octaves.
Frequency (Hz) EQ1
/frequencyhz1 - The filter frequency is expressed in Hz (cycles per second). This parameter set to 1000 has exactly the same effect as the above parameter set to 3.
/bandwidth1 - Bandwidth determines how much the levels decrease near the center frequency, expressed in octaves.
Similar parameters for EQ 2 and EQ 3.
Parameters - Common Page
Scope - The filter effect can be limited to only some of the channels by placing their channel names here, e.g.
The python member
.chanIndex can be used to apply a different parameter value for each channel.
Frequency Modulation Channels Input
The second input is the Frequency Modulation Channels, which allows the filter parameters to be changed within the CHOP's time slice interval (typically 1/60 sec). This prevents audible stepping of the parameters that you are changing quickly.
You can send in a channel called
frequency to override the value of the parameter. You would do this if you want to adjust the center frequency very quickly. The parameter can only change as fast as the timeline rate, typically 1/60 seconds. Changed quickly, the stepping in frequency is noticable. To improve on that, you would send a
frequency channel in that is at a higher sample rate, like 400, which you can set in a CHOP like an LFO CHOP.