Firstly, while the Sanchun SC-180A is purchased as a finished product selling for around $250, it is advertised as DIY upgradable. It is essentially a passive four input balanced/line level switch box and a 300 step R2R volume control with enough space inside the cabinet to fit a DIY amplifier or preamplifier board. Both XLR and RCA output whatever input is selected at the same time so you can connect a power amp via XLR and a subwoofer via RCA.
If the component labelling is to be believed, it is fitted with a mix of Nichicon and Chemi-Con electrolytic caps, Sprague orange drop caps, Dale resistors and Japanese Takamisawa relays. The main PCB has four mystery ICs (ID has been sanded off) mounted underneath and another two on the LED display board. The case is nicely made from aluminium and features a large LED display that shows input source and volume level. It also comes with a small plastic remote control.
On power up, a relay clicks and the front display immediately lights up. You then hear a second click from the large blue relay that closes the terminals on an unused green terminal block. I suspect this is used to activate power supply to any boards you add. Eight seconds after power up, you hear two more relays click connecting the XLR and RCA outputs. You can individually set the starting volume of each of the four inputs or have them all the same.
I have ordered a cheap Accuphase C-3850 preamplifier kit and a 12-0-12 + 15-0-15 toroidal to fit into the Sanchun but I am having trouble identifying where to connect the C-3850 lines in/out to this board other than connecting it between the line level cabling between the RCA inputs and the main PCB.
If the component labelling is to be believed, it is fitted with a mix of Nichicon and Chemi-Con electrolytic caps, Sprague orange drop caps, Dale resistors and Japanese Takamisawa relays. The main PCB has four mystery ICs (ID has been sanded off) mounted underneath and another two on the LED display board. The case is nicely made from aluminium and features a large LED display that shows input source and volume level. It also comes with a small plastic remote control.
On power up, a relay clicks and the front display immediately lights up. You then hear a second click from the large blue relay that closes the terminals on an unused green terminal block. I suspect this is used to activate power supply to any boards you add. Eight seconds after power up, you hear two more relays click connecting the XLR and RCA outputs. You can individually set the starting volume of each of the four inputs or have them all the same.
I have ordered a cheap Accuphase C-3850 preamplifier kit and a 12-0-12 + 15-0-15 toroidal to fit into the Sanchun but I am having trouble identifying where to connect the C-3850 lines in/out to this board other than connecting it between the line level cabling between the RCA inputs and the main PCB.
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