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11
Configuration
Since the SMR™821a is an analog product‚ there is not a lot of configuration to worry about. No
software‚ no data cables‚ no networks and no headaches. However‚ there are a few things to
remember while you begin to use your new SMR™821a mixer.
The SMR™821a is shipped from the factory ready to go. You should be able to follow the steps below
and get audio through the unit.
The first step is to calibrate your gain settings for the inputs. Each microphone input has a Gain
Control and a Level Control. These controls work together while the Status LED and the master Level
Meters provide a visual indication of the control’s behavior. To properly adjust the SMR™821a for
optimal performance‚ follow these simple steps for each input channel:
1. Adjust the Channel‚ Left‚ Right and Aux Level Controls so they are at the midpoint. There is a
center detent on the control which indicates this position.
2. Adjust the channel Gain Control to its minimum position—fully counter-clockwise—for the
channel you want to set.
3. Apply an audio signal to the input by either playing a line level audio source or by speaking into
a microphone at a nominal level. While monitoring the master Level Meters‚ slowly adjust the
Gain Control clockwise while audio is present. Keep turning the control until the Level Meters
are indicating nominal level—around the -6 dB to 0 dB area on the meters. In addition‚ the
channel Status LED should be green—not red. The bi-color Status LED illuminates green when a
signal is present at -20 dBu. It illuminates red when the signal level is near clipping. The Level
Control adjusts the signal level sent to the mix buses. This control should be operated near the
mid-point of its travel to assure an optimized signal-to-noise ratio and maximize headroom‚
once the Gain Control is properly set. If you find that the input signal is too
hot and you cannot properly adjust the Gain Control without causing a
clipping condition‚ you will need to use the Pad Switch‚ located on the rear
panel. This switch will give you an additional 20 dB of pad beyond what the
front panel Gain Control provides. Follow this procedure for each input to
ensure proper gain structure.
Figure 7.
Input Channel Controls
Figure 8.
Master Meters and Controls
Figure 9.
Stereo Input Channels
There is no Gain Control for channels 7 and 8. To properly adjust the gain on
these channels‚ you will need to control the output level of the audio source.
With the Channel Level and the Master Level controls at the detent position‚ a -
1o dBV signal will present a +4 dBu output at the Bus Output connectors.
It is important to adjust the gain down enough so the preamp will not clip at
louder levels. Carefully consider the type of audio source and adjust the gain
settings accordingly. Material with wide dynamic range will generally require a
lower gain control setting‚ while material that is fairly constant‚ can usually
tolerate a higher setting.
After these adjustments are made‚ make sure you monitor the front panel LEDs
and meters during normal use. Take note of the action of the Status LEDs.
Under normal operation‚ you should see lots of green with an occasional flash
of red. Constant red‚ however‚ indicates that a gain setting is improperly
adjusted and should be reset using the above procedure.