Surround Channel Level Test Signals

There are many options available to generate test signals for your speakers in a surround system. The goal is to send a signal that represents a typical sound yet does not interact with other basic settings or room problems. This is represented by a band limited pink noise signal that evenly places the majority of the energy between 500 Hz and 2 kHz. These frequencies bypass the region where bass modes and bass management effect the level yet is wide enough to cover several octaves. Bass modal problems would cause the results to vary greatly with location in many rooms. A signal with several octaves range will average the effects of comb filtering and speaker frequency anomalies in this range. Sound in this frequency range also targets key frequencies for dialog intelligibility and is where a high percentage of music and dialog sound will be present.

Problems exist with test signals found on discs and in devices. These include signals that are not band limited well or the levels are not consistent with the LFE channel level test. Avia and Gold Line offer discs with signals that represent these standards while Digital Video Essentials (DVE) has channel levels that are inconsistent with the LFE channel test and are not as well band limited as Avia or Gold Line. Many receivers and preamp processors also have these same problems. The Avia and Gold Line DVD’s are the sources I recommend for those who wish to check or set their channel levels. Measurements of test signals from these three sources are shown below.

W. Jeff Meier

ISF and THX Certified Home Theater Consultant

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