Theater Calculators
Subwoofer Quarter/Eighth Space Placement Estimator
https://www.theatersizing.com/calculators/subwoofer-boundary-gain/
Estimate only — not a calibrated SPL meter, an acoustic report or an electrical design. Confirm with measurement.
Subwoofer Quarter/Eighth Space Placement Estimator
Each nearby large boundary can add about 6 dB. Floor only is half space (+6). Floor+wall is quarter (+12). A corner is eighth (+18). Smoothness is not included.
Inputs
Results
- Boundary gain
- 12dB
- Corrected SPL
- 102.0dB
Calculation method
Gain = 6 dB × number of boundaries (0–3). Add to an anechoic SPL.
Exact formula
G = 6N, N ∈ {0,1,2,3}. Limits: infinite rigid planes, no room modes, no destructive interference at the seat.
Frequently asked questions
Is +18 dB real?
In a textbook eighth-space, toward 18 dB. In a leaky living room, less, and lumpy.
Dual subs?
Two locations beat one louder corner. This tool is one sub.
Raise it off the floor?
That removes a boundary and the +6 that came with it.
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