GainClone ver 1 - LM3875T with 2000uF per rail

My decision of building a GainClone amp starts from a day I read a forum about a very simple power amplifier based on a chip. This design orginally came from a company called 47 laboratory. The orginal design is called GainCard and it got some good reviews over the internet and many people started building some clones from the design, therefore the name GainClone. Since the design is so simple that I could build it easily and so I gave it a try.

My design is based on one of the non-inverted design with the modification of replacing the 1000uF caps with 2000uF.



Aluminum case with attenuator as volume control

Internals : Dual Mono configuration, 2x 18V 250VA transformers, 8 diode (MUR860) per channel


Close up on the 2 channels, I used Kynar insulated 30AWG silver plated wire for signal interconnects. The heatsink used is a copper heatsink for 1U server.

Close up on LM3875, the 2 caps are Panasonic FC Cap, 2000uF per rail, total 4000uF per channel.


The schematic is very similar to the one at the Chill Amp page :

However, I removed the input DC filter caps. and the 1000uF caps are changed to 2000uF. I do this because I know my CD output has no DC offset, so I removed the input caps to get a better bass. Also I am going to use this Amp to drive my 4ohms speaker, I need bigger caps to provide enough current to the chip.

The power supplies I used are two 18V 250VA transformers.




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