ART Pro Audio Pro Channel - Mic Preamp/Compressor/EQ - Manual (Page 11)

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before disconnecting microphones.
Another Note: Most dynamic microphones won’t be affected or damaged if they are
plugged into the Pro Channel when phantom power is turned on (we haven’t run across
any). However, if the mic doesn’t need it, don’t use it. Some things are best left
untested!
Phase Switch
The Phase switch is used to reverse the phase of the signal leaving the Pro Channel’s
preamp section. The Phase switch reverses the polarity of the Preamp Output jack and
everything after it in the signal chain. In the Normal position (out), the signal is in-
phase. In the Reverse position (in), the polarity of Pins 2 and 3 of the Output XLR jack
(and the Tip of the ¼” jacks) are reversed and the signal is changed to 180 degrees out
of phase with the input signal.
In multiple microphone applications, mic placement can affect the phase of a signal. If
two microphones pick up the same signal from different locations, the result can be a
hollow or “frequency-shifted” sound; in some cases it may sound as if an instrument
disappears completely. Depressing the Phase switch can remedy this problem.
Note: In single microphone applications, switching the phase will produce no audible
change in the output signal.
Tube Drive/Gain Reduction Display
The top LED display (directly under the VU meter) shows how the tube gain is affecting
the input signal. These LEDs are calibrated with the tube circuitry to give you an
accurate representation of the tube’s output signal. The Tube Character LEDs measure
the signal level before the Preamp Output level control—use them as a visual guide for
setting the Gain control.
The first four (green) LEDs are labeled “Cln.” The tube is producing a clean output
when these are lit. The next four (yellow) LEDs are labeled “Warm.” This is the optimal
operating range for the Pro Channel’s preamp. At this level, the tube is producing an
output signal that most would term “warm” (or whatever you’d like to call it—
simmering, toasty, etc.) You’ll find the output signal has an enhanced bottom to low
mid quality with smooth high frequency detail.
The last two (red) LEDs are labeled “Clip.” The first red LED will light approximately
6dB before audible distortion occurs. If this light flickers, don’t panic. The unique
design of the Pro Channel allows the tube to distort well before any other gain stage.
When a tube goes into distortion, it’s a gradual process and tends to sound pleasing for a
range before it turns into a distortion box. You may also find that a “clipped” level is
suitable for some applications.
Preamp Output Control
The Preamp Output control sets the output level of the preamp section. In most
situations you’ll set this control around 12 o’clock (or its “0” setting). The Preamp
Output control has a range of no output (from its fully counter-clockwise position), to