Crown Audio IQ P.I.P.-DSP manual Auto Standby, ODEP Limiter, Excessive IOC Warning

IQ–P.I.P.–DSPProgrammable Input Processor with DSP for IQ Systems

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

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