Project 2004: My Chip Amp - Gainclone

This is a clone of the highly acclaimed SakuraSystem Gaincard amplifier.

I have built a couple of these Gainclones. 
1. A four-channel power-amp used as my main amplifier with my Thule pre-amp for normal stereo
and also for DD and DTS surround.
2. A two-channel integrated amp with potentiometer, for my bedroom stereo.
+ a few more.


4-channel Gainclone:
This gainclone has a 12-volt trigger standby circuit (between the transformers)
which is connected to the Thule preamp through an i/o port and data cable.
This circuit enables the Thule preamp to power-on the Gainclone's main PSU from standby mode, 
and also turn off the main PSU back to standby mode. LED on front is red in standby mode and green
in power-on mode.

A special thanks to Max Jens Jensen for designing this standby circuit, and also for designing the PCB-layouts of the amplifier
and bridges PCBs and for providing parts.
See more pictures of this standby circuit here.

Details:
32 MUR860 diodes for bridges
Elna 1000uf caps
ERO MKP1841 film caps
Allen Bradley resistors
Caddock resistors
LM3875T opamps
500VA, 24,6 volt AC, MU-metal shields
Homemade pcb's
Monacor case
Solid rubber feets.

Thanks to Ole Nielsen for providing parts for my DIY amplifiers during the years.

This pcb can be used with two variations of a Gainclone circuit:
Variation 1 (the one I use)
Variation 2
Comments:
Variation 1: Use C5 0,1uf and R2 220K at pin 7. Use C4A 2,2uF at input. Do not use R6.
Variation 2: Do not use C5 0,1uf but only R2 18K at pin 7. Use C4 4,7uF at input. Use R6 22K.