Transistor stereo bass booster

This is a bass booster circuit that uses transistors as a base. It is designed to increase the low frequency of audio.

They are cheaper than ICs or normally circuit. Because of use each channel only 2 transistors together with resistor and capacitors approximately ten parts only.

Transistor stereo bass booster

In the circuit, Adjust potentiometer trimmer, 10-50K to turns a level of bass level up and down as you want.


Figure 1 is the circuit diagram on mono or signal channel. But the PCB layout below is stereo or dual-channel. Most people like it.

Working principle

Transistor stereo bass booster circuit

The Transistor stereo bass booster circuit

I do not like to read a lot of text. You may also same me. So, I keep the shortest explaining you.

Here is the step process:

C1 coupling an input signal into the base circuit of Q1 at pin B.

Both resistor R1 and R2 are biased currents to Q1, for first preamplifier section.

Then, a higher signal comes out of E of Q1. The voltage does not change but higher current. It keeps impedance to low.

To drive RC networks to separate and increase the bass signal to higher from other frequencies.

But the signals come out of the R C networks will be too lower.

So, we need to amplify to more with Q2 and a few parts.

After that, some signals at output goes back as a feedback signal to the R-C network circuit. To boost up a signal again.

Also bass booster circuits  below

How to builds

Building this project is easy. Just use a 12V power supply regulator that smooth enough.

It may be connected via R-100 ohms and has C-100uF 16V to ground.

As Figure 2 All resistors in circuit use 0.25 W.

Then, the wiring to a circuit and various components. You can view the example in Figure 2.

But look be carefully for the polarity of electrolytic capacitors, legs of the transistors. Must be correct only!

PCB layout
Component layout of Transistor stereo bass booster

Components layout of Transistor stereo bass booster


This circuit requires 12V DC voltage Regulator.

The components List

Q1-Q4: 2SC1815 or 2SC945 or 2SC458, NPN transistors

Electrolytic Capacitors
C1,C6: 10uF 16V
C5: 33uF 16V

Polyester Capacitors
C2: 0.033uF 50V
C3: 0.0022uF 50V

0.25W Resistors, 5% Tolerance
R2: 680 ohms
R3: 47K
R4: 2K
R5: 5.6K
R6: 24K
R7, R9, R10: 4.7K
R8: 39K
R11: 27K
R12: 220K
R13: 20K
R14: 3.3K
R15: 560 ohms
R16: 33K

Other see text.

What is more? Not only that.

Loot at This Active Bass Boost circuit

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I always try to make Electronics Learning Easy.


  1. mr.newbie

    wew… It work… Nice bass..tnx..plzz tell me what transistor pre amp with mid range that work??coz i build the tri amp and the three band using ne5532..its not woking..plz

  2. surya

    i want to run this same circuit using 5v,because iwant connet to pc supply (USB port)
    so what the changes i must do ??..sir

  3. jason

    evening sir , is the wattage of its resistor is 1/4 W ?

  4. Jesus

    Does this amplifier outputs only amplified low frequencies, or it outputs high and low frequencies, but with the function of manipulating the low frequency amplification?

  5. Sanjeev Kumar

    Dear sir where to connect ground supply or take out ground

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