Crown Audio IQ P.I.P.-DSP - Manual (Page 17)

Page 17
IQ–P.I.P.–DSP Programmable Input Processor with DSP for IQ Systems
Reference Manual
output limiters are controlled by the IQ System and has
five parameters:
Output Limiter: Turns this function on/off.
Threshold: Sets the threshold, in dB, above which
the limiter acts. The level is based on the scaled
output voltage monitors (see Section 4.4). The
range is from 0 dB to –40 dB.
Attack Time: Sets the attack time of the limiter. The
attack time is defined as the time it takes the limiter
to attenuate the input signal by 10 dB. The range is
from 10 milliseconds to 30 seconds.
Release Time: Sets the release time of the limiter.
The release time is defined as the time it takes the
limiter to increase the input gain by 10 dB. The
range is 100 milliseconds to 30 seconds.
Ratio: The compression ratio is fixed at ¥:1.
4.14 Auto Standby
The Auto Standby feature automatically turns off the
high-voltage supplies of the amplifier when no audio
signal is detected at the input for a predetermined
period of time. The channels are controlled
independently. Using it, many
IQ Systems can pay for
themselves in just a few years due to reduced energy
costs. There are four parameters which control this
feature:
Auto Standby: Turns this function on/off.
Standby Level: Sets the level, in dB, below which
the high voltage supply of an amplifier channel will
be turned off. The range is from +16 dBu to –40
dBu.
Standby Time: Sets the time, in minutes, that the
input signal must remain below the Standby Level
before the channel’s high-voltage supply is turned
off. The range is from 0 to 255 minutes. A setting of
0 (zero) yields a turn-off delay of approximately 2
seconds to facilitate setup of the function.
Use Turn-On Delay: Enables or disables the IQ
address turn-on delay. This is a delay that prevents
all the amplifiers from turning on at the same instant
and tripping power breakers when an “all amps on”
command is issued by the
IQ System. The turn-on
delay is calculated by: 10 msec x IQ address
value. It may be desirable to disable this turn-on
delay when using the Auto Standby feature so that
the first syllable of speech is not missed when a
voice page suddenly causes the Auto Standby
function to turn a high-voltage supply back on.
4.15 ODEP Limiter
The effects of “ODEP limiting” the drive level of the
output devices (as described in Section 4.5) are very
audible. To overcome this, an
ODEP limiter is available
to proportionally limit the input audio signal as the
thermodynamic energy reserve of the amplifier is
consumed. This helps to prevent the amplifier from
“
ODEP limiting” the drive level of the output devices as
described earlier. In the majority of cases, limiting the
input signal produces a very smooth sound. And since
the input signal is only limited when and to the degree
necessary, it is very difficult to detect. There are four
parameters which control this feature:
ODEP Conservation: Turns this function on/off.
ODEP Trigger Level: Sets the ODEP level, in
percent, above which the conservation limiting will
begin. The range is from 1 to 100%.
ODEP Conservation Amount: Sets the amount,
in dB, that the input signal level will be attenuated
for each percentage point that the
ODEP level
exceeds the trigger level. The range is ½ to 6 dB in
½-dB steps.
ODEP Conservation Release Time: Sets the
release time of the conservation limiter. The release
time is based on 10 dB of attenuation. For example,
a setting of 10 seconds will result in the
IQ–P.I.P.–
DSP taking 10 seconds to release 10 dB of
attenuation. The range for this parameter is 200
milliseconds to 30 seconds.
4.16 Excessive IOC Warning
A “trigger” can be set that will cause a warning
message to appear on the host computer’s screen if
too many
IOC events occur over a specified length of
time. Three parameters control this feature:
IOC Error Detect: Turns this function on/off.
IOC Error Time: Sets the time interval over which
IOC events will be counted. The range is from 1 to
10 seconds.
IOC Error Count: Sets the number of IOC events
that must occur during the preceding time interval
before a warning message is displayed.
Note: An
“IOC event” is one complete on-off-on cycle. The
range is from 1 to 100 events per unit time
4.17 Excessive ODEP Warning
The user can set a “trigger” that will cause a warning
message to appear on the host computer’s screen if
the
ODEP level ever rises above a predetermined level.
It is generally assumed that a sudden rise in the ODEP