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LM3886 Amp: Circuit of Audio Power Amplifier

Author: Irene
Date: 21 Feb 2022
 12924
lm3886 amplifier

Introduction

LM3886 is a high-performance audio power amplifier. It exhibits extremely low THD+N values of 0.03% at the rated output into the rated load over the audio spectrum and provides excellent linearity with an IMD (SMPTE) typical rating of 0.004%. It is very suitable for enthusiasts who pursue both beautiful sound quality and strong volume. This article introduces several practical applications of LM3886 in home theater systems.

This is a technical examination vedio of the LM3886 Amplifier.

Catalog

Introduction

Catalog

I High Quality Dual-channel Power Amplifier

II Powerful BTL Power Amplifier

III Subwoofer Speaker

IV FAQ

Ordering & Quantity

I High Quality Dual Channel Power Amplifier

LM3886 outputs nearly 70W power at rated voltage and the peak power is 150W. The dual-channel power amplifier adopts a simple and typical circuit, which can replace a variety of HI-FI power amplifiers,  and is suitable for the left and right main channel of a power amplifier in home cinema. The whole circuit is installed on the same PCB. Each of the two LM3886s is equipped with a special aluminum radiator (length 140, thickness 50, height 75 (mm)), which are fixed on both sides of the PCB to facilitate heat dissipation. The power transformer can choose double 24~28V, 3~5A.

II Powerful BTL Power Amplifier

A pure BTL bridge amplifier is composed of an operational amplifier NE5532, an LM3886 in-phase amplifier, and an LM3886 inverting amplifier, which can easily output more than 200W undistorted power. It can be used in dance halls, karaoke, theaters, and other occasions. This circuit can keep the sound quality natural and smooth when playing at a low volume. BTL Power amplifier circuit is shown in Figure 1. One circuit board for each channel, with independent rectification. The size of the two radiators is 140mm in length, 50mm in thickness, and 100mm in height.

  Figure 1. BTL Power Amplifier Circuit

III Subwoofer Speaker

Figure 2 is the circuit of a household subwoofer speaker.  

Figure 2. circuit of subwoofer speaker

In the picture, the Linkwitz active compensator accurately controls the center frequency f1 of the compensation peak and its Q value, so that the closed box (see Figure 3) with a natural corner frequency of about 50 Hz and the frequency response curve (see Figure 4) extends down flatly. The low end -3dB point reaches 25Hz.

Figure 3. Closed box 

 

Figure 4. frequency response curve

In Figure 4, curve A is natural frequency response; B is compensation curve; and C is system frequency response. The turning frequency of the low-pass filter is continuously adjustable from 80Hz to 200Hz, so that the active subwoofer can match the reader's dual channel speaker with different frequency limits. The loudspeaker uses silver flute YD310-43. The basin diameter is 310mm. The magnet diameter is 158mm. The resonance frequency is 25Hz. Q=0.35. The continuous power is 50W, and the sensitivity is as high as 95dB. Compared with the Hivi S8 unit with a sensitivity of 88dB, the sensitivity difference between the two is 7dB. For the closed box, the output sound pressure of Yindi YD310-43 when it input 50W is equivalent to the output of Hivi S8 unit when it input ≥200W.

 

Yindi can also be replaced by the Blue Whale YD310-8XA. Instead of the bass reflex with poor transient performance and low sensitivity, it is better to use the simplest closed box. The box shall be solid and air tight, filled with glass fiber cotton or acrylic cotton for warmth absorption, and the small cavity at the bottom of the box shall be used to install the circuit part. For the sake of simple installation, all circuits are installed on the PCB. The PCB, radiator, switch and I/O connector are fixed on the metal panel, and then fixed on the speaker with 6 screws. Then, it can work after connecting to horn and transformer. Connect the subwoofer active speaker with the home stereo speaker to form a 3D playback system.

IV FAQ

What type of amplifier is LM3886?

High-performance audio power amplifier

 

What is the THD+N value of LM3886?

0.03%

 

What type of systems is LM3886 used for?

Home theater systems

 

What is the peak power of the LM3886?

150W

 

How much power does the LM3886 output at rated voltage?

70W

 

How much undistorted power can a BTL bridge amplifier output?

200W

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