ENSONIQ ASR-10 Manuel d'instructions télécharger pdf (Page 208)

Section 11 — WaveSample and Layer Parameters

About Filters 5

ASR-10 Filters

Each ASR-10 voice has its own pair of digital filters, F1 and F2, that are connected in series. The

filter settings determine which frequencies will be allowed to pass through to the output.

Low-Pass and High-Pass

A low-pass filter allows only those frequencies below the filter cutoff frequency to pass—higher

frequencies are filtered out. The reverse is true for the high-pass filters. In the ASR-10, the first

filter (F1) is always a low-pass filter. The second filter (F2) can be either a high-pass or low-pass

filter.

Poles — Rolloff Curves

“Pole” is an engineering term that describes the steepness of a filter. Each additional pole gives a

filter a steeper rolloff curve. In the ASR-10, four poles are available, but they are divided between

two filters; either as 2 and 2, or as 3 and 1. A single-pole filter will rolloff at 6 dB per octave; a 2-

pole, 12 dB per octave; a 3-pole, 18 dB per octave; and 4-pole, 24 dB per octave. To reproduce a 4-

pole low-pass filter (for that “classic” analog synth sound) you would set both filters to 2-pole

low-pass. Each filter would then roll-off at 12 dB per octave, resulting in a total 24 dB per octave

rolloff.

Cutoff Frequency

Every filter has a “knee” in the response curve, known as the cutoff frequency. This is the

frequency at which the filter begins filtering out frequencies. The filter cutoff frequency can

remain fixed over time, or it can be varied by modulating the filter with an envelope, LFO,

velocity, etc. You can create some very interesting filter configurations by using a different

modulator for each filter. For instance, try using pressure to modulate the filter. You can drive

one filter up with pressure, while simultaneously driving the other down.

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ENSONIQ ASR-10 Manuel d'instructions Page 208