How to build a versatile preamplifier circuit

How to build a versatile audio pre-amplifier circuit

For most of the audio amplifier circuits, a small preamplifier circuit has to be added for initial handling of audio signals for quality reproduction at the end. For this normally a simple pre-amplifier has to be constructed and it can be added to most of the audio power amplifiers. 

You can easily build a small signal audio pre-amplifier for handling audio signals before amplification. Though the pre-amplifier actually amplifies the normally feeble audio signals to sufficiently optimal level for further amplification and processing at audio amplifiers. 

Know your circuit

The circuit schematic of the pre-amplifier is given below. The circuit is a very simple one uses just a few components. It can be built for a low cost since very few components are used. The low noise pre-amplifier gives very good audio output signals are further amplified with suitable audio power amplifiers. Study the circuit and the schematic very straight-forward. Even a novice can easily understand the circuit design. 

Parts list

S. No	Item	Description	Quantity
1	T1	Transistor BC 549 C	1
2	T2	Transistor BC 549 B	1
3	C1, C4	10 MFD electrolytic capacitor	2
4	C2	10 KPF ceramic capacitor	1
5	C3	220 MFD electrolytic capacitor	1
6	C5	4.7 MFD electrolytic capacitor	1
7	R1	560K ohms Resistor	1
8	R2	5.6K ohms Resistor	1
9	R3	47 ohms Resistor	1
10	R4	6.8K ohms Resistor	1
11	R5	33K ohms Resistor	1
12	R6	1.5K ohms Resistor	1
13	Bat	9V Battery	1
14	S1	On/off switch	1

Know your design

The pre-amplifier is designed with two NPN silicon transistors BC 549. The Input signal is fed to transistor T1 via C1. The amplified signal is again amplified in the Transistor T2. The amplified audio signal is taken out from the emitter of T2 via C5. The circuit works with 9V battery supply.  

know your assembly

The circuit can be easily assembled on a small veroboard or general-purpose PCB. The size of the assembly is very small and it can be attached to any audio power amplifier unit cabinet itself.  

In nutshell

Build this low-noise versatile audio pre-amplifier circuit by yourself as DIY project. It can be used wherever for amplification of low audio signals before feeding to audio power amplifiers. Give your valuable suggestions and comments.