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Simple Audio Compressor Circuit

Think like music have one volume knob.

Range that is dynamic? It is how far volume go from very soft to very loud.

Compressor do this job it move knob by itself.

When sound is too loud it make little lower and when it is too quiet it push it little louder.

So all sound come more same level which is not too loud not too soft.

Good for music or sound where volume go up-down too much.

Circuit Working:

Parts list:

ComponentQuantity
Resistors (All resistors are 1/4 watt unless specified)
10k1
100k1
5.6k1
12k1
220k1
1k1
Capacitors
Ceramic 47nF2
Ceramic 470nF1
Electrolytic 1µF 25V1
Semiconductors
Transistor BC5472
Diodes 1N41484

This audio compressor circuit uses only one main part and that is T1 transistor.

Audio connects through C1, R1, D1 and then C2 and R3.

Same times small part of audio connects to D3 and D4 and these make control voltage for T1.

How fast volume fade or change? that depends on C4 and R5.

Even if audio input change a lot like 50dB the output will stay around plus minus 3dB.

This circuit works good in transmitter use.

Formula:

This design controls the audio signal gain based on how loud it is.

This way we can make a Simple Audio Compressor Circuit.

It reduces the dynamic range and loud sound become less loud and quiet sound become little louder.

How to find Compression Ratio:

Compression ratio (R) tell us how much signal strength go down after some loud limit.

Formula is:

R = ​Vout​​ / Vin

where:

To control this ratio we can change transistor bias and feedback parts.

This circuit uses BC547 transistors and give base idea how to make audio compressor.

We can adjust it more for better sound or for special audio need.

How to Build:

To build a simple audio compressor circuit follow the below steps for connections:

Note:

Conclusion:

A simple audio compressor circuit is often used in audio recording, mixing and for broadcasting.

It help make sound better, control loud and soft parts and stop audio gear from getting too much signal.

Also it is used in music instruments, sound systems and telecom equipment.

Check sound stay clear, same level and easy to hear.

References:

Audio compression circuit and method

Dynamic range compression

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