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Copyright
2008 FiveFish Studios
www.fivefishstudios.com
SC-1mk2 Microphone Preamp Kit
LED or Light Emitting Diode
The LED chosen is small in size, small in power consumption, crystal clear when OFF, but bright red when
turned ON. Lower power consumption means less heat, and less current draw from the power supply. High
efficiency means the LED lamp is bright even without using a lot of current. This is a little more expensive
than your normal, old-style LED lamp that consumes about 20mA of power. This LED uses only 4.9mA.
Just like a diode, there is a required correct polarity orientation for it to work properly.
Jumper Terminals
To facilitate easy setup, jumper terminals are used in the SC-1mk2 Mic Preamp. There is (1) jumper terminal on the board
labeled JP2. (JP1 has been removed from the SC-1mk2 model.) In normal use, the header terminals must be shorted and
“jumpered.”
Solder the short ends of the HEADER to the PCB as shown on the photo on the right.
INSERT Solder Pads and JP2 jumper
You’ll notice (3) solder pads on the PCB, behind the blue potentiometer. These are the INSERT Solder Pads.
Pin 1 = very bottom hole = GND = Ground Terminal
Pin 2 = middle hole = SEND
Pin 3 = top hole = RETURN
In normal operation, JP2 shorts the SEND solder pad to the RETURN solder pad.
TROUBLESHOOTING NOTE: If you forget to put in jumper JP2, you will NOT hear any sound from your preamp. So if you’re not
getting any output, check that JP2 is connected and shorted with a jumper jack.
So what’s the INSERT Solder Pads for? You can wire the preamp to optionally use an INSERT TRS Jack.
These 3 pads connect to a switching TRS jack. You must then wire the TRS jacks properly so that without any external jack
plugged in, the SEND and RETURN makes an automatic connection. If you plug in an INSERT CABLE, the internal connection is
broken and the signal is routed to the external signal processing device, and brought back to the preamp using the RTN pad.
Therefore…. If you’ll be wiring an optional INSERT JACK with your SC-1mk2 preamp, remove jumper JP2. Otherwise, leave jumper
JP2 in place. See page 16.
