Op-Amp Audio Amplifier

In the below circuit is a versatile audio amplifier employing a low cost LM358 op-amp. The differential inputs give the amplifier excellent immunity to common-mode signals which are a common cause of amplifier instability. The dotted ground connection represents the wiring in a typical project illustrating how the ground sensing input can be connected to the ground at the source of the audio instead of at the amplifier where high currents are present. If the source is a power supply referenced signal then one of the amplifier inputs is connected to the positive supply.

For example, an NPN common-emitter preamplifier may be added for very high gain and by connecting the differential inputs across the collector resistor instead of from collector to ground, destabilizing feedback via the power supply is greatly reduced.

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This entry was posted on Monday, January 21st, 2008 at 5:33 pm and is filed under Audio power amplfier, Audio preamp circuits, Electronics And Projects, Schematics. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.