Summit Audio MPC-100A Mic Preamp Compressor - Manual (Page 3)

THE CONTROLS
1. Line/Mic/48 3 position switch selects the input being used, line or mic, and also
engages the phantom power +48 volts for condensor microphones
2. Pad/-20 2 position switch engages 20 dB of input signal attenuation
3. Phase/180 2 position switch engages a 180 degree phase shift of the signal
4. DI Input 1/4" mono jack accepts Hi-Z instruments such as electric guitars
and basses; a direct input into the preamp tube, bypassing the input
transformer
5. Loading variable resistor for impedance matching of the Hi-Z input (range
is 10k to 1M ohms); adjust for desired upper harmonic content in
guitar sound
6. Gain 12 position rotary switch controls signal gain in the input preamp only
note: for Hi-Z input only top 7 positions have any effect (as shown in
blue)
7. OL left yellow LED indicates preamp vacuum tube saturation; when
LED is blinking, the tube is just entering soft clipping
Compressor Section Controls:
8.Gain variable resistor controls compressor vacuum tube gain
9. OL right yellow LED indicates compressor vacuum tube saturation; when
LED is blinking, the tube is just entering soft clipping
10. A.C. Threshold variable resistor sets the signal amplitude threshold, above
which compression engages
*NOTE!!! A setting of 10 yields the least compression, whereas a setting of 0
yields the most compression
11. Slope variable resistor controls the magnitude of compression (sometimes
referred to as ratio); a setting of 10 yields maximum compression,
whereas a setting of 0 yields the least compression
12. Attack 3 position switch selects fast, medium, and slow compression response
time to input signal peaks; this is how fast the compression can kick in
13. Release 3 position switch selects fast, medium, and slow compression release
time; this is how long it takes the compressor to stop attenuating signal