Prototype Power Amplifier

posted in: Audio Projects 0

This unit was capable of approximately 85W RMS with a peak power output over 100W! This was the first amplifier I built that was over 50W as well as the first time I used this particular audio amplifier IC. This prototype would lead to several more refined versions that eventually became the amplifier I used for my DJ business.

In this photo the prototype is sitting on the Custom Speaker System I built specifically for this design. The board on the right is the power amplifier main board, consisting of both the left and right channels, along with support components, including National Semiconductor LM3886T power amplifier IC, capacitors and output inductor coils. The board on the left is the main power supply for the amplifier only. It is sitting on top of its power transformer and provides +/- 37 VDC.

The small board on the bottom left is a temporary volume control board mounted on a small piece of PCB. This was used to limit volume from a CD player during testing until the Prototype Audio Controller was finished. The schematic used was a slight variation of the reference schematic in the datasheet for the amplifier IC. This type of amplifier is also called a “gain clone” amplifier. When I have time I will try to redraw the schematic and post it. Either way I plan to visit such a project again since I purchased enclosures specifically for a final version that was never realized.

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