Sound Performance Lab Parametric Equalizer owner manual Parametric Highpass Bandpass Lowpass

CONTROLS

Fig. 11:

Notch:

Curve 1: Q = 1,5;

Roll-Off = steep

Curve 2: Q = 0,2;

Roll-Off = steep

Curve 3: Q = 1,5;

Roll-Off = gentle

Curve 4: Q = 0,2;

Roll-Off = gentle

PARAMETRIC,

HIGHPASS,

BANDPASS,

LOWPASS

a notch across the audio spectrum. A further creative use is to create a pseudo stereo image from a mono signal by split- ting the signal and applying different notches to each of the two channels. If these two channels are then panned left and right in the final mix, it creates an illusion of space. The position, number and width of the notches must be fine tuned by ear.

Curves 2 and 3 show an alomst identical response in Fig.

11.Nevertheless there is an audible difference that is much greater than shown in the graph.

The 4-way rotary switch sets the equalizer function (Parametric, Low-pass, High-pass, Band-pass), although if you select Notch this overrides whatever other equalizer mode has been selected.

When using these three modes you should be aware that the filters are connected in series, and depending on the fil- ter types and settings, it is possible to set up a situation where there is no output at all. For example, if one filter is set as a High-pass filter with a cut-off frequency of 1kHz, everything below 1kHz will be attenuated. If this signal is now fed into the next stage, set as a Low-pass filter, with a cut-off frequency of 500Hz, it will pass only signals below 500Hz. As the first filter’s output contains little or nothing below 1kHz the result is very little signal.

For this reason, Band-pass filters are often used on their own while High-pass and Low-pass are usually used as a pair to provide control over the extremes of the audio spectrum. Conversely, they can be used to ‘bracket’ a narrower section

20 OPTIMIZER