Loop Configurations Explained: why one size does not fit all

Summary

A loop distributor's guide to perimeter, cancellation, figure-of-eight and array loops, with its rules of thumb on how far a loop's field spills and how metal in floors limits a simple loop's width.

Key findings

• Says a perimeter loop is the easiest and, where it works, cheapest layout, but that large areas, spill control or metal loss can rarely be handled with one.
• Warns never to install a perimeter loop at listening height: in its example, 0.25 m vertically from the loop, the field was about -1 dB at the centre of the room and over +9 dB at the edge, outside the standard's tolerance; the further the loop is from the listening plane, the more even the field.
• Gives the widest floor-level perimeter loop as about 22 m for seated listeners (listening plane 1.2 m) and 26 m for standing listeners (1.7 m) with no metal; over standard reinforced concrete 6-10 m (5-9 m standing), heavy reinforced concrete 3-6 m (2-5 m), a metal system floor or steel deck 1-3 m (2-3 m), and under a glass or metal suspended ceiling 3 m.
• Says a perimeter loop's spill field extends one to two times its width, with a signal above -32 dB (the background noise level it treats as the limit) still present there, so a 5 m loop may still radiate above that level 5-10 m away.
• Says metal loss correction flattens the response at only one point, so in larger loops some areas stay under-corrected and others over-corrected; where the field varies by more than 6 dB, smaller multiple loops are needed. Moving the loop away from the metal, for example to ceiling level, is offered as another remedy.
• Describes a cancellation loop as a simple, relatively low-cost way to cut spill in one or two directions, at the price of part of the room lacking full coverage.

Limits

A distributor's guide based on its own design tools and products, with field plots but no measured sites or data behind its width table and spill figures. The page shows no date; it refers to IEC 60118-4:2006, since replaced by the 2014 edition, and the site footer gives copyright 2012.

Read the original

www.univoxaudio.co.uk/knowledge-centre-wiki/a-guide-to-induction-loops/loop-configurations

Link checked 9 October 2026. We link to the original and do not host copies.

Cited in

• Where do hearing loops fall short: metal, spill, noise and upkeep?Partly answered

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