56W High-Performance Audio Amplifier with LM3876 IC + PCB

Fig. 1 – High Performance 56W Audio Power Amplifier using LM3876 IC with PCB

This is a High Performance 56W Audio Power Amplifier, based on the LM3876 Integrated Circuit, with great sound quality, powered by a symmetrical power supply.

The Amplifier responds very well in all audible frequency ranges from 20Hz to 20Khz, and has a minimalistic and very compact design, which makes this amplifier a good choice to be assembled with little difficulty.

LM3876 Integrated Circuit Description

The LM3876 is a high-performance audio power amplifier capable of delivering 56W of continuous average power to an 8Ω load with 0.1% THD+N from 20Hz–20kHz.

The performance of the LM3876, utilizing its Self Peak Instantaneous Temperature (°Ke) (SPiKe) protection circuitry, puts it in a class above discrete and hybrid amplifiers by providing an inherently, dynamically protected Safe Operating Area (SOA) SPiKe protection.

Means that these parts are completely safe-guarded at the output against overvoltage, under-voltage, overloads, including shorts to the supplies, thermal runaway, and instantaneous temperature peaks.

The LM3876 maintains an excellent signal-to-noise ratio of greater than 95dB (min) with a typical low noise floor of 2.0μV. It exhibits extremely low THD+N values of 0.06% at the rated output into the rated load over the audio spectrum, and provides exceptional linearity with an IMD (SMPTE) typical rating of 0.004%.

Feature

56W Continuous Average Output Power into 8Ω
100W Instantaneous Peak Output Power Capability
Signal-to-Noise Ratio ≥ 95 dB(Min)
An Input Mute Function
Output Protection from a Short to Ground or to the Supplies Via Internal Current Limiting Circuitry
Output Over-Voltage Protection against Transients from Inductive Loads
Supply Under-Voltage Protection, not Allowing Internal Biasing to Occur when |VEE| + |VCC| ≤ 12V, thus Eliminating Turn-On and Turn-Off Transients
11-Lead TO-220 Package
Wide Supply Range 20V – 94V

🔌 The Schematic Circuit

In Figure 2 below we have the components arrangement of the power amplifier circuit with the LM3876 IC, and as we can see, the difficulty is not extreme.

Since there are few external components, making the amplifier circuit very simple to assemble, and a technician or hobbyist with medium experience can assemble it without much difficulty.

It is important to remember to be careful when assembling the circuit, not to invert any component such as capacitor diodes, or even when connecting the symmetrical voltage of the power supply. Not to invert the voltage poles, because the integrated circuit or other components can be damaged.

The coil is formed is a 5uH coil, for those who are going to assemble it, you can assemble it with 10 turns of 18 AWG Wire with a 3/8″ air core.

Fig. 2 – Schematic Circuit High Performance 56W Audio Power Amplifier using LM3876 IC

🧾 Component List

Semiconductors

U1 ………….. LM3876 Integrated Circuit

Resistors

R1, R5 ……. 1K resistor (brown, black, red, gold)
R2, R3 ……. 18K resistor (brown, gray, orange, gold)
R4 ………….. 10K resistor (brown, black, orange, gold)
R6, R7 ……. 22K resistor (red, red, orange, gold)
R8 ………….. 100Ω resistor (brown, black, brown, gold)
R9 ………….. 10Ω / 1W resistor (brown, black, black, gold)
RP1 ………… 10K Potentiometer

Capacitors

C1 …………….. 2.2μF Ceramic/Polyester Capacitor
C2 …………….. 220pF Ceramic/Polyester Capacitor
C3 …………….. 47 Ceramic/Polyester Capacitor
C4, C5 ………. 22μF / 65V Electrolytic Capacitor
C6, C7, C8 …. 0.1uF Ceramic/Polyester Capacitor
C9, C10 ……… 2.200uF / 65V Electrolytic Capacitor
L1 ……………… Inductor 5uH *Ver Texto

Others

P1, P2 ………… Screw Terminal Type 5mm 2-Pin Connector
P3 ……………… Screw Terminal Type 5mm 3-Pin Connector
J1 ……………… Set of male connectors 2-Pin (Optional)
Other ………….. PCB, Wires, Speaker, Heat Sink, etc.

⚡ Power Supply

The power is supplied through a 24 VAC transformer with center tape, i.e. [+VAC | GND | -VAC], after rectification the source will supply 35 VDC.

It is a standard power supply voltage for this amplifier to work with little heating and little distortion, as it works with a minimum of 18V and a maximum of 84V.

The current to power this amplifier is of at least 2A, and if it is going to use in stereo mode, two of these same ones, this current has to be doubled to 4 Amperes.

In Figure 3 below, we have a suggestion for a power supply that we use in our projects. In this article, besides having the schematic diagram with the Printed Circuit Board, you will understand how to easily calculate your own Power Supply, with the desired voltage.

You can in the link below:

Symmetrical Power Supply for Power Amplifiers using Calculation + PCB

Fig. 3 – Symmetrical Power Supply for Power Amplifiers

🖨️ Printed Circuit Board (PCB)

In Figure 4, we provide PCB – Printed Circuit Board, in GERBER, PDF and PNG files. These files are available for free download, on MEGA server, in a direct link, without any bypass.

All to make it easier for you to do a more optimized assembly, either at home, or with a company that prints the board. You can download the files in the Download option below.

Fig. 4 – PCB – High Performance 56W Audio Power Amplifier using LM3876 IC

📥 Files to download, Direct Link:

Click on the link beside: GERBER, PDF and PNG files

✨ Our Gratitude and Next Steps

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The ElCircuits Team ⚡