Stereo preamp is important part of audio system, it makes weak sound signals from mic or other devices and is stronger for better use.
The LA3161 is a two-channel preamplifier chip designed for car stereos; it produces low noise, performs reliably and requires only a few external components.
It also includes built-in voltage control to reduce noise and improve sound quality.
Hence, this Stereo Preamplifier Circuit using IC LA3161 explains how LA3161 preamp circuit works, how to build it, with formulas and ends with a conclusion.
Circuit Working:
Parts List:
| Components | Values | Quantity |
|---|---|---|
| Resistors (All resistors are 1/4 watt unless specified) | 100k | 2 |
| 7.5k | 2 | |
| 100Ω R5 and R6 | 2 | |
| 150Ω | 1 | |
| Capacitors | Ceramic 1000pF | 2 |
| Ceramic 0.01µF 2 | 2 | |
| Electrolytic 47µF 25V | 3 | |
| Electrolytic 10µF 25V | 4 | |
| Semiconductors | IC LA3161 | 1 |
This circuit runs on 12V power and LA3161 IC can take up to 18V and 200mW power.
Also, audio left and right go in through C8 pin 1 and C9 pin 8 to block DC., then C10 and C11 remove high-frequency noise.
After that, IC boosts weak audio signals.
Now R1, R4, C1 and C2 control gain and frequency and C4 and C5 let only AC audio go to output.
Therefore, the left and right outputs can go to the next amplifier or operate directly and C6 and C7 stabilize the power supply and reduce noise.
Formulas with Calculations:
Here are simple formulas for LA3161 stereo preamp circuit:
Voltage Gain (AV):
AV = R4 / R3
= 100k / 7.5k = 13.33
Signal gets about 13 times louder.
Cutoff Frequency (fC):
fC = 1 / (2πRC)
= 1 / (2π × 100k × 10nF) = 159.15 Hz
Hence, this sets the low-frequency limit of the sound.
How to Build:
To build a Stereo Preamplifier Circuit using IC LA3161 following are the steps we need to follow the assembling:
- First, collect all parts shown in the circuit diagram.
- Next, connect pin 1 of LA3161 to audio left input using capacitor C8.
- Add capacitor C10 between C8 and ground (GND) to filter noise.
- Then from pin 2 connect R2, R1 and C1 in series.
- Also, connect capacitor C6 and resistor R6 from pin 2 to GND.
- After that, connect pin 3 to audio left output through capacitor C4.
- Now connect pin 4 to +12V supply through resistor R7.
- Also place capacitor C7 between +12V and GND for power filtering.
- Further, connect pin 5 directly to GND and connect pin 6 to audio right output through capacitor C5.
- Now from pin 7 connect R3, R4 and C2 in series and also connect capacitor C3 and resistor R5 from pin 7 to GND.
- Finally, connect pin 8 to audio right input using capacitor C9 and then add capacitor C11 between C9 and ground to reduce noise.
Conclusion:
To conclude, Stereo Preamplifier Circuit using IC LA3161 is easy to make and works well, it uses few parts and boosts sound nicely.
Moreover, we can change part values to control sound gain and frequency and it is also good for people who love electronics and audio projects.