Studio Technologies 72 - Manual (Page 7)

Model 72 User Guide Issue 2, July 2004
Studio Technologies, Inc. Page 7
Model 72
Level Meter / Interface
Intercom Audio Levels
In North America the two most common
intercom systems are those from RTS
and Clear-Com. From tests performed
in Studio Technologies’ lab the nominal
RTS TW-series audio level was approxi-
mately –10 dBu. The dynamic range
control provided by belt-packs such as
the MP-325 was very good, limiting the
maximum level to at most 10 dB above
the nominal. The nominal audio level as-
sociated with a single-channel Clear-Com
system was harder to characterize. It ap-
peared to be a few dB less than –10 dBu,
but with a much larger dynamic range.
Level peaks of 10 to 20 dB over nominal
were easy to produce.
The contents of this section, along with the
previous one, may elicit howls of protest
from a host of engineers and intercom-
system experts. But for years we’ve heard
differing reports as to the actual nominal
audio levels for RTS and Clear-Com
systems. The “in-the-know cats” agreed
that the nominal level of RTS TW-series
intercom (and 4000-series IFB) was
–10 dBu, a value that we confirmed in our
tests. But the nominal level for Clear-Com
party-line systems was variously reported
as –20, –15, –12, –10, and “you know,
the Clear-Com level!” It’s most likely that
early Clear-Com systems did use a nomi-
nal level in the –20 dB range. But after
making controlled tests, their contempo-
rary equipment seemed to be much
closer to –10 dBu. And with the limited
dynamic-range control that we experi-
enced, the actual level during operation
may vary widely.
In conclusion, the engineers at Studio
Technologies are always open to learning
more. Additional information from the field
concerning IFB and intercom system lev-
els would be welcomed. Stopping by our
offices for an in-person chat would be also
great. (And bringing along pizza and beer
for a tech-talk session would certainly get
our attention!) Just park the production
trailers on the street!