Accurate Bass Tone Control
Circuit diagram:Accurate Bass Tone Control Circuit Diagram
The analogue selectors used may be driven by mechanical switches, standard logic circuit or a microcontroller. The selectors used in the present circuit are Type SSM2404 versions from Analogue Devices, which switch noiselessly. Each IC contains four selectors, so that a total of eight are used. The step size is 1.25 dB at 20 Hz with a maximum of 10dB . The circuit can be mirrored with S1, which means that a selection may be made of amplification or attenuation of bass frequencies. The user can choose between attenuation only and extending the range by dividing R9. The control can be bridged by switch S2.
To prevent the output impedance of the circuit having too much effect on the operation of the circuit, the output impedance must be ≤ 10 Ω. Resistor R1 2 protects the circuit against too small a load. At maximum bass amplification at Ui n = 1 V r.m.s., the THD+N <0.001% for a frequency range of 20 Hz to 20kHz and and a bandwidth of 80kHz. The circuit draws a current of about 10 mA.