1. GAIN CONTROL. Available on L and R channels. Adjusts the gain of the audio channel, with units around the 7th dial (1 hour). Throttling usually requires some makeup gain to compare IN/BYPASS. The Gain control can also be used as a tape level.
2. REDUCTION CONTROL. Available on both L and R channels. Cutout adjusts the amount of limiting or compression on that channel. This could also be called a “threshold”. Turning this control clockwise increases the amount of limiting or compression.
3. VU METER. One for each channel, showing the gain reduction in dB when switch #7 is unchecked and showing the output level in dB when switch #7 is turned on and lit.
4. HP SC CONTROL. Inserts a high-pass filter into the sidechain circuit, reducing the amount of compression or limiting below 80 Hz. Note: this filter can be changed to 150 Hz via an internal jumper. See the manual for details.
5. INPUT/BYPASS CONTROL. If the switch is turned on and illuminated, the audio will pass through the limiter/compressor circuit and all front panel controls will work. If the switch is off, audio still flows through the Unity tubes, but with Unity Gain without compression or limiting.