Abbingdon Music Research LS-77 owner manual AppendixB - Abbingdon Acoustic Setup Regime

AppendixB - Abbingdon Acoustic Setup Regime

The Abbingdon Acoustic Setup Regime (AASR) is a process of optimising the Speaker/room/listener placement interactively, repeatable and is rooted in decades worth of practice. AASR takes account of the simple fact that no rigid mathematical principle, no simulation software and no measurement system currently available correlates reliably with subjectively perceived "good sound". AASR is concrete and reliable science, not some form of voodoo, though the process is very involved and some of it will seem somewhat unconventional. Using AASR provides an imaging and sound-staging that is exceptional. Non of the mathematical based procedures even takes these two matters into account.

The most basic requirement for AASR is to establish the Zone Of Least Interaction (ZOLI) with walls. This area is found in every listening room and is usually two to five feet long (60-150cm). It is the region most likely to be free of the listening room's most severe acoustical interaction. The first stages of determining the zone will produce a largish area, but at this point the rough dimensions must be regarded only as a basic starting point.

With the aid of a friend who does not mind feeling a little foolish, place yourself in the target listening position while your assistant speaks in a moderately loud voice at constant level, projecting into the room. Alternatively, use your own voice and walk in similar patterns listen to how your voice interacts with the room. Give it a few tries and listening very hard you will know what it is about. When you or your assistant comes to the boundary of the ZOLI (zone of least interaction) nearest to the side or rear wall the voice will become more prominent in lower frequencies and will seem to have more energy. When exiting the ZOLI towards the middle between wall again a distinct change in vocal tonality will be heard.

The first step is used to determine the zone relative to the back wall, so the person speaking should start at the back wall, in front of the listening position, walking toward the listening position while speaking. As the speaker approaches the listening position, the voice will appear to 'free up' as it is relieved of the low frequency energy imparted by the closeness to the rear wall. In other words, you are listening for the point in the room where the rear wall stops to reinforce bass. When this point is reached, mark the floor with a piece of masking-tape or similar.

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