Gain Structure
Page 19
Peavey Electronics Corporation
Adjusting Full-Scale Input Sensitivity and Output Drive Settings in Legacy Mode
If the MM-8802 is operating with current software, ( MWare
™
V3.1.2 or X-Frame
™
88 V2.0) these settings are adjustable from
the software controls. If the MM-8802 is connected to a MediaMatrix system of an earlier vintage, then these software
controls, as well as all other analog controls, are disabled. In this case, the MM-8802 operates in “legacy” mode, and acts just
like an older BoB. In legacy mode, you must adjust the analog Full-Scale Input Sensitivity and Full-Scale Output Drive level
with the DIP switches. The illustration below shows the layout of the MM-8802’s internal DIP switches. These switches per-
form the same function as the software based Full-Scale Input Sensitivity and Full-Scale Output Drive controls shown on page
21. The range of adjustment is the same, and there is a switch for each input and output channel.
The default settings provide for a 12 dB loss through the MM-8802. This is done intentionally to maintain compatibility with
older BoBs. The illustration below shows the DIP switches as they appear on the circuit board at the factory default settings.
NOTE: If you are running new software and can see the Full-Scale Input Sensitivity and Full-Scale Output Drive con-
trols, as shown on page 21, then the DIP switches are NOT active. Software control will override these switches.
The DIP switches are located on the main circuit board inside the MM-8802. To gain access, remove only the top cover of the
unit. The switches are located on the center of the circuit board, adjacent to the input boards. It will be obvious, since these
DIP switches are the only DIP switches used on the MM-8802’s main board. There are four 8-position DIP assemblies. Each
channel is controlled by two switches, each with an “up” and “down” position. If the switch is located in the center of its trav-
el, it is not adjusted correctly. Just below the switches is a printed key of the switch positions and their relative levels. The key
applies to all channels.
Front
Rear
Adjustment of the DIP switches requires access to the inside of the MM-8802. It is highly recommended that this proce-
dure be performed ONLY by qualified service personnel. Remove the power cable prior to removing the cover. There
are dangerous voltages present inside the unit, as well as static sensitive components. Damage to the MM-8802’s inter-
nal components caused by unqualified persons performing this procedure will void the warranty.
W A R N I N G ! !
Full-Scale Output Drive
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 of the MM
™
-8802 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 MM-8802 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 MM-8802 or the levels inside the DPU.
In our previous example, we would be g23.0 dB at the input to the MM-8802’s digital to analog (D/A) converter. This is
full-scale, as determined by the input, and the DPU processing. The actual analog audio level at the MM-8802’s output is deter-
mined 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 down-
ward 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 MM-8802 would be exactly the same as
the input level of +18.0 dBu.
