MM
™
-8802 User Manual
Page 16
http://aa.peavey.com copyright 2000 All Rights Reserved
Gain Structure
Gain structure is among the most important, often debated and misunder-
stood topics in the audio industry. For years, engineers have disagreed with
each other about proper levels, gain I/O, meters and other issues that affect
the way we work. When digital audio came into the mainstream, the topic’s
confusion was only compounded, and today, few fully understand the inner
workings of gain structure. This is true within MediaMatrix
®
as well.
Although this manual does not present an exhaustive discussion on the
topic, it is important to understand the basics of gain structure, and how it
relates specifically to the MM-8802.
When the MM-8802 was designed, several important issues regarding the
gain structure of its input and output sections were carefully considered.
There were performance issues, interface, ease of use and compatibility
issues that played a big part in how the product was eventually designed.
In order to provide support for the thousands of MediaMatrix systems
already installed, the MM-8802 was designed with a unique contrast of old
and new. Essentially, the MM-8802 operates in one of two modes, “New” or
“Legacy” mode. These modes of operation extend to many facets of the MM-
8802’s functionality, but most significantly to the management of its gain
structure.
When running in New mode, the MM-8802 includes functionality that sup-
ports software control of all analog settings when using current (MWare
™
V3.1.2 or X-Frame
™
88 V2.0, or higher) software. When running in Legacy
mode, that is, systems that are running older software, the adjustments of
Full-Scale Input Sensitivity and Full-Scale Output Drive levels are adjustable
from internal DIP switches. In this mode, the MM-8802 acts just like a lega-
cy BoB.
The legacy BoB models (MM-8830, MM-8840, MM-8848) did not include
support for software-based analog gain control. The only adjustments that
could be made were by internal jumpers for Full-Scale Input Sensitivity and
Full-Scale Output Drive level. And, because real-world conditions prevent a
universal standard, it was possible that the factory settings would not be
appropriate for many projects. The likelihood was that, sooner or later, a
contractor would have to open the unit to adjust the analog settings.
It is very important to understand that it is the software that determines
what mode the MM-8802 is operating in, NOT the interface connector. The
new software includes support for control of the Full-Scale Input Sensitivity
and Full-Scale Output Drive settings directly from the control panel as well
as input and output analog gain (trim). When these software controls are
available, all internal hardware switches are bypassed.
The software controls are explained on page 21. For legacy operation, you
will need to use the MM-8802’s internal DIP switches to adjust analog Full-
Scale Input Sensitivity and Full-Scale Output Drive levels.
