User manual

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This +23.0 dBu level represents 0 dB on the front panel meters. Remember, the +23.0 dB DPU
level is always the maximum fullscale level that can be received by, or sent to the CAB 4n.
Anything above +23.0 dB (DPU level) that is sent to the CAB output block, and thus, to the
CAB’s D/A will be clipped. The additional 12 dB of headroom is only available within the DPU.
What about the outputs? The outputs are easy....just set the drive level you want. The full-scale
DPU levels will be available at the output side of the MM modular card installed in a CAB 4n
and at your choice of analog levels, so you don’t take a performance loss if you need a lower
output level to match the input sensitivity of your power amplifier. Likewise, if you use the CAB
4n to drive line-level audio over long distances and need to use a higher drive level, you still get
the same, full-scale performance. Also, the setting of the Full- Scale Output Drive level does not
affect the levels coming into the Cab 4n or the levels inside the DPU. In our previous example,
we would be getting +23.0 dB at the input to the CAB’s digital to analog (D/A) converters. This
is full-scale, as determined by the input, and the DPU processing. The actual analog audio level at
the Cab’s output is determined by the position of the Full-Scale Output switch. Remember, it
doesn’t matter which output setting you choose, you still get full-scale performance. Just like the
input side, these switches allow you to “shift” your dynamic range upward or downward to match
your application. If you choose a +6 dBu setting, then the full-scale analog output level will be +
6.0 dBu. As in our example, a +18.0 dBu setting would give you unity gain and the output level
of the Cab 4n would be exactly the same as the input level of +18.0 dBu.