Audio Engineering

224 Chapter 7

capacitors and is therefore free from any possibility of introduced distortion, whereas
the “ active ” network requires an internal gain block, which is not automatically above
suspicion.

In reality, however, any passive network must introduce an attenuation, in its fi at response
form, which is equal to the degree of boost sought at the maximum “ lift ” position, and
some external gain block must therefore be added to compensate for this gain loss.

This added gain block is just as prone to introduce distortion as that in an active network,
with the added disadvantage that it must provide a gain equal to that of the fi at-response

Lift

Cut

Gain (dB)

 12

 12

0

100 200 400 800

Frequency

50 Hz 1.6 K 3.2 K 6.4 K 12.8 K 20 kHz

Figure 7.56 : Graphic equalizer response characteristics.

Gain (dB)

Frequency adjust

Frequency

Lift

Cut

Figure 7.55 : Parametric equalizer control.