I always recommend relatively many circuits or project on the pre tone control. Today we see other interesting project. (Please do not get bored them).
We can divide normally type of the tone control are 2 types as following.
1. Passsive Tone Control
2. Active Tone Control
A stype of the passive tone control circuit be shown in figure 1. We do not widely used this circuit. Because sound quality is reduced and low performance.
Figure 1 Typical passive tone control
We like to use. the active tone control type that most familiar. is the Baxandall type circuit As shown in Figure 2.
Advantage of this active tone control type is not cause loss signal. We may understand the function of this circuit easier. By considering the comparison of circuit in Figure 3.
See that the gain of the circuit is equal to the Rb / Ra. So if Rb = 10Ra we have gain = 10.
IF Ra=Rb will be gain = 1
If we return to consider in figure 2, will seen that C1, R1 & C2 + R2 is connected together that the velue its Impedance will decrease as the frequency increases.
If we adjust RV1 Ra1 value is greater than C1 + R1. then The gain of the line M in figure 4.
On the contrary, if we adjust the volume in the other direction. Will have gain of circuit as line N. In figure 4 RV1 serves as the Treble control.
Then consider the P3 + C3 and C4 + R4 will see that resistance is even higher. When lower frequency so have the gain of circuit as figure 4 then P, Q to R5-resistor that serves as a separate circuit, the two part, not to interfere with each other.
Which in practice. Can not be strictly separated circuits. That is when we adjust the bass – treble would be with prejudice.
how modify so May be split both control circuit independent decisively as show in figure 5
From these principles, we can design the tone control circuit solutions.As circuit shown in Figure 6.
We use the circuit of TR1, TR2 transistor acts as a Matching circuit. Between input and this super tone control. By Q1 is connected as emitter follower type. and have Q2 is a constant cureent cource circuit.
The IC1-LF353 will act as the adjust treble sound. And IC2-NE5532N serves as a fine bass voice. Because the normal tone control and pre amplifier will work best well. When they is driven by a circuit with low impedance, and the load applied to a high resistance.
IC1___________LF353 Wide Bandwidth Dual JFET Input Operational Amplifier or NE5532N or M5218
*** but M5218 is very old ICs.
Q1, Q2________BC549 45V 100mA NPN Transistor
1/4W +/- 1% Resistors
R1, R5, R15___________2.2K
R2, R16______________100 ohm
R4, R8, R9, R11, R12____10K
R7, R10, R13, R14______100K
VR1, VR2______________100KB Linear Potentiometer
VR3____________________50KACT non Linear Potentiometer
C1, C2, C7______________10uF 16V
C12, C13________________100uF 25V
C3, C4__________________0.0047uF 50V
C5, C6__________________0.047uF 50V
C10, C11________________0.1uF 50V
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