Practical tools for measured work
First Reflection Point Calculator
Locate symmetric side-wall first reflection points with the mirror-source method and real room coordinates.
The side-wall markers come from the mirror-source method. They identify geometric specular paths at seated ear height.
How it works
How to use it: enter the speaker and listener coordinates measured from the front wall, plus each speaker inset from its side wall.
Method. Each speaker is mirrored across its adjacent wall. A straight line from listener to mirror intersects the real wall at the first reflection point.
Example. In a symmetric 4.2 m room, both wall points occur at the same distance from the front wall.
Current-input example
The result above uses these exact values. This snapshot is included when the page is printed so the output can be checked against the original measurements.
- Room width
- 4.2 m
- Room length
- 5.5 m
- Listener from front
- 3.4 m
- Speakers from front
- 0.6 m
- Speaker side inset
- 0.8 m
Primary result: Left wall point: 1.37 m from front.
Before using the result
- Measure from the datum or reference edge described by this tool, and do not mix inside, outside and centerline dimensions.
- Keep inputs in the displayed units and preserve more precision than the final cutting or purchasing tolerance requires.
- When the result is close to a limit, verify it with a test piece, field measurement, manufacturer drawing or qualified project professional.
Limitations
This solves horizontal specular geometry only. Speaker directivity, toe-in, ceiling and floor paths, seat width, panel size and absorption bandwidth matter. Confirm with a mirror test or measurement.
Frequently asked questions
How large should a panel be?
The point is only a centre reference. Panel size should cover movement across the listening area and the relevant speaker radiation, with practical mounting tolerance.
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