Figure 8 and Figure 9 illustrate the loudness characteristics

obtained with C

being kept at the nominal 0.01 µF. These values naturally

modify the bass tone response as in

Figure 2 and Figure 3.

With pins 9 (loudness) and 14 (volume) directly connected,

loudness control starts at typically −8 dB volume, with most

of the control action complete by −30 dB.

Figure 10 and Figure 11 show the effect of resistively offset-

ting the voltage applied to pin 9 towards the control refer-

ence voltage (pin 19). Because the control inputs are high

impedance, this is easily done and high value resistors may

be used for minimal additional loading. It is possible to re-

duce the rate of onset of control to extend the active range to

−50 dB volume control and below.

The control on pin 9 may also be divided down towards

ground bringing the control action on earlier. This is illus-

trated in

Figure 12, With a suitable level shifting network be-

tween pins 14 and 9, the onset of loudness control and its

rate of change may be readily modified.

When adjusted for maximum boost in the usual application

circuit, the LM4610 cannot give additional boost from the

loudness control with reducing gain. If it is required, some

additional boost can be obtained by restricting the tone con-

trol range and modifying C

lustrating this for the case of bass boost is shown in Figure

13. The resulting responses are given in

Figure 14 showing

the continuing loudness control action possible with bass

boost previously applied.

DS101125-10

FIGURE 7. Loudness Compensated Volume

Characteristic

DS101125-11

FIGURE 8. Loudness Compensated Volume

Characteristic

DS101125-12

FIGURE 9. Loudness Compensated Volume

Characteristic

DS101125-13

FIGURE 10. Loudness Compensated Volume

Characteristic

DS101125-14

FIGURE 11. Loudness Compensated Volume

Characteristic

DS101125-15

FIGURE 12. Loudness Compensated Volume

Characteristic

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