User guide

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CHAPTER 5
The Measurements
5.3.2. Description of the Measurement
SIM 3 utilizes an advanced implementation of the IFT that prevents the “phantom echoes” or
“wrap-around” artifacts of conventional sampling algorithms.
Delay Finder is useful for identifying:
■ Time offset between the reference and measurement channels
■ Timing and relative level of echo structures
■ Time domain characteristics of filters and circuits
■ Polarity
■ The physical and/or electronic alignment of sound sources / loudspeakers - within
components of an individual system at crossover, and among arrays of loudspeakers
■ Determining the correct delay times for supplemental and fill loudspeakers
Delay Finder is a necessary first step before SIM 3 can accurately perform frequency re-
sponse measurements; you must first match any time delay between the measurement
points in the system. Delay Finder displays measurement data in terms of amplitude and
time, reporting amplitude and time in milliseconds in the Room, Processor, Result and
Room+Processor views.
NOTE: For all Delay Finder measurements, set the Analysis Time window
long enough to capture the latency or propagation time, from +/-70 ms to
+/-560 ms. This time window will be the same for each view. Set the Amplitude
Threshold above the noise floor of the systems being measured, but below the level
of the signals to be measured.
The Delay Finder traces show the following:
■ Room Trace — the time in milliseconds for the audio to travel from the loudspeaker
output of the processor to the measurement microphone. This measurement includes
any processing, amplification, the loudspeakers and the room itself.
■ Processor Trace — any delay within the processing signal chain itself.
■ Result Trace — the sum of Processor and Room delays, which is the time between
the audio signal leaving the mixing console (source) and arriving at the measurement
microphone.
■ Room+Processor View — shows the previous two measurements on different graphs,
so the contribution of each element to the total delay can be separated.