Super pre tone control project using LF353

I often recommend you many preamplifiers with tone control circuits. Today we will see other interesting projects. (Please do not get bored them).

Also, it used LF353 or NE5532 as the main parts and helping of a transistor. To increase high power gain.

Today we will see other interesting projects. (Please do not get bored them).

Super Preamplifier Tone control circuit project using NE5532 and LF353

Types of tone controls

We can divide normally type of tone control are 2 types as follows.

  • Passive Tone Control
  • Active Tone Control

Passive tone control

A style of the passive tone control circuit is shown in figure 1. We do not widely use this circuit. Because sound quality is reduced and low performance.

typical passive tone control circuitFigure 1 Typical passive tone control

Active Tone Control

We like to use it. the active tone control type that most familiar. is the Baxandall type circuit As shown in Figure 2.

negative feedback pre tone control circuit baxandall type

Figure 2: The typical negative feedback tone (Baxendale type)

The advantage of this active tone control type is not caused loss signal. We may understand the function of this circuit easier. By considering the comparison of the circuit in Figure 3.

Basic feeback circuit of op-amp
Figure 3: The simple feedback circuit

See that the gain of the circuit is equal to the Rb / Ra. So

  • Rb = 10, Ra we have gain = 10.
  • Ra=Rb, The gain will be 1


If we return to consider in figure 2, will see that C1, R1 & C2 + R2 are connected together that the value its Impedance will decrease as the frequency increases.

If we adjust VR1, the Ra1 value is greater than C1 + R1. Then, the gain of line M in figure 4.

behavior of negative feedback tone control overlap effect exaggerated
Figure 4 Behavior of negative feedback tone control (overlap effect exaggerated)

How does circuit works

On the contrary, if we adjust the volume in the other direction. Will have gain of the circuit as line N. In figure 4 VR1 serves as the Treble control.

Then consider the P3 + C3 and C4 + R4 will see that resistance is even higher. When lower frequency so has the gain of the circuit as figure 4 then P, Q to R5-resistor that serves as a separate circuit, the 2 parts, 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

sequential 2 stage tone control avoids-inter action between controls

Figure 5 Sequential two-stage tone control which avoids inter-action between controls.

From these principles, we can design the tone control circuit solutions.As circuit shown in Figure 6.

Super pre tone control project using LF353
Figure 6 Super tone control circuit.

We use the circuit of TR1, TR2 transistor acts as a Matching circuit. Between input and this super tone control. We connect Q1, emitter follower type. And have Q2 is a constant cureent cource circuit.

The IC1-LF353 will act as the adjust the 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 drive a circuit with low impedance, and the load applied to high resistance.

To avoid hum noise in the background.
Use: 15V Dual power supply

How to build

Order to PCB layout and positioning devices in Figure 7 . I can not tell how many, because I believe you can do it.


Figure 7 PCB of Super tone control

PCB layout of this project

PCB layout of this project

Part list

IC1: LF353, Wide Bandwidth Dual JFET Input Operational Amplifier or NE5532N
Q1, Q2: BC549, 45V 100mA NPN Transistor

0.25W +/- 1% Resistors
R1, R5, R15: 2.2K
R2, R16: 100 ohms
R3: 270K
R4, R8, R9, R11, R12: 10K
R6: 2.2K
R7, R10, R13, R14: 100K
R15: 3.3K
VR1, VR2: 100KB Linear Potentiometer
VR3: 50KA CT non Linear Potentiometer

Electrolytic Capacitors
C1, C2, C7: 10uF 16V
C12, C13: 100uF 25V

Polyester Capacitor
C3, C4: 0.0047uF 50V
C5, C6: 0.047uF 50V
C8: 0.001uF 50V
C9: 0.01uF 50V
C10, C11: 0.1uF 50V

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