Associated with a small FET input stage, this amplifier is ideal for beginners to make some small electric guitar amplifier. Don’t think you will get results similar to those offered by the amps of a certain class, but for someone who starts in the DIY, and choosing a good size of speaker driver, it’s a nice little montage.

Possible simplification :

• A component that you can try to remove: R4 + R5 + C7 C5, C6. And finally, you can also try to remove R6 and C8, while not forgetting to replace R6 with a strap (for short circuit, if you prefer), just to see what happens when at maximum volume.
• The number of components in the preamp section can be reduced … a different preamp and easier. Maybe you’ve seen a small preamp with two resistors and a FET type PN4221: it is very difficult to get any easier, but these transistors is outdated. You can experiment with other types of general FETs.

PCB Layout

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This Low voltage bridge audio amplifier circuit is for low voltage applications requiring high power outputs. Output power  levels of 1.0 W into 4 ohm from 6 V-and 3.5 W into 8 ohm from 12 V are typical. Coupling capacitors are not necessary since the output dc levels will-be within a few tenths of a volt of each other. Where critical matching is required the 500 K potentiometer is added and adjusted for zero dc current flow through the load.

Parts list :
R1, R2, R3, R4 : 270 ohm
R5 : 2,7 ohm
VR1 : 10K
VR2 : 500K Variable
C1, C2 : 20uF
C3 : 0.05uF
C4 : 0.1uF
IC1, IC2 : LM386

Note :

Vs = 8V   RL = 4 ohm   Po = 1 W

Vs = 12V   RL = 8 ohm   Po = 3,5 W

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