Page 6
Copyright
2008 FiveFish Studios
www.fivefishstudios.com
SC-1mk500 Microphone Preamp Kit
Transistor
We’re using a transistor as a switching device in the SC-1mk500 Mic Preamp Kit. The transistor has (3) legs, the Collector, Base
and Emitter terminals. Looking from the top, the transistor has a half-circle shape, like a half-moon.
Take note when inserting transistors that you do not insert them backwards. Otherwise, phantom power will not work, and
possibly even ruin the transistor. The flat side should be facing to the right.
Grayhill Selector Switch
The SC-1mk500 uses a sealed, high-performance, high-quality, 12-position, Grayhill selector switch. This is one of the most
expensive items in this kit.
Some boutique preamp manufacturers also use Grayhill selector switches for their preamps. They are durable, reliable, have a
nice solid feel to it, and provide good resistance to RF Interference. This switch will be the most commonly used/abused
mechanical device on the SC-1mk500 preamp. I want this part to withstand being turned and turned and turned.
DPDT Switch (Dual Pole, Dual Throw.)
The SC-1mk500 also use a high quality, PCB mounted DPDT switch. This is another one of the expensive items in the kit. Again,
since this is a mechanical device, I want it to withstand repeated use of toggling on and off.
You need to toggle the switch to the leftmost position (pointing to the LED) to turn on phantom power. If you mount the SC-
1mk500 PCB vertically, the switch will be turned ON pointing upwards. If you mount the SC-1mk500 PCB horizontally, the
switch will be turned ON pointing left, towards the LED.
Bourns Sealed Potentiometer
This is another high-priced item in this kit because it is another mechanical component and I want this part to withstand the use
and abuse of being rotated constantly. I want it to provide a smooth feel, and not wore out easily, and become “scratchy” like a
cheap, carbon potentiometer. I want it to have a longer life than plain “guitar potentiometers.” This is also sealed from the
elements so dirt, grime, oil, and impurities will not contaminate the resistive element and produce a “scratchy” volume control.
The resistive element inside is made of conductive plastic. Unlike carbon potentiometers, these will last a very long time even
after repeated rotations.
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.
