Speaker Coverage Planner — Frequently asked

Inverse-square law: SPL(d) = sensitivity + 10·log10(power_W) - 20·log10(distance/1m). At sensitivity 100 dB SPL @1W/1m, driven with 400W RMS, at 8m listener distance: SPL = 100 + 10·log10(400) - 20·log10(8) = 100 + 26 - 18 = 108 dB. The calculator runs this exact math. Its limits: it assumes free-field propagation (no room reflections), single-cabinet contribution (no array summation), no air-loss at high frequencies, and the manufacturer's rated sensitivity (which is an anechoic average — real cabinets vary 2-3 dB across the frequency band). For final venue design, manufacturer prediction software (Soundvision for L-Acoustics, ArrayCalc for d&b, K-array proprietary) models all of these and produces per-seat SPL maps.

Because line-array geometry exists to control vertical coverage taper across audience depth. Each cabinet narrowly aims a slice of the seating; assembling 6-12 cabinets in an array creates continuous vertical coverage from front-row to back-row, with each cabinet's vertical splay calibrated so that distant rows receive the same SPL as close rows. Wide vertical dispersion would put energy on the ceiling and the floor — wasted energy that returns as reverberation. The narrow vertical control is the engineering value of line array.

Touring brands (L-Acoustics K-Series, d&b V/Y/J, K-array Mugello, JBL VTX) prioritise SPL output, transport durability and rapid rigging; they cost more per box but justify it on tour. Install brands (L-Acoustics A-Series, d&b Y/E-Series, K-array Pinnacle, JBL VRX/AC) prioritise low visual profile, longevity in fixed installations and cost-per-seat efficiency. For permanent worship and auditoria, install tiers are usually correct. For premium concert and event-grade installations, touring-grade cabinets earn their premium through headroom.

100V line distributes amplifier output through a step-up transformer, recovers at each speaker through a step-down transformer. Loses 1-2 dB per 100m of cable run — negligible. Default for distributed BGM in restaurants, retail and large public spaces where many small speakers are wired across long distances from a central amp. Low-impedance (8 ohm typical) delivers higher peak SPL with lower distortion and full bandwidth. Default for live events, premium worship, theatre and serious AV where SPL and fidelity matter more than wire cost.

When the source material extends below the main cabinet's low-frequency rolloff. Most install line-array boxes roll off around 60-80 Hz; touring cabinets sometimes to 50 Hz. Kick drums, bass guitar, electronic music, film LFE channels and orchestral percussion all extend to 30-45 Hz — outside main-cabinet bandwidth. Pairing 2-6 subwoofers (depending on room size) with mains is standard for live amplified music. For speech-priority installations (worship sermons, conferences) subs are often unnecessary; the main cabinet's natural rolloff matches voice fundamentals.

Per-seat SPL prediction with real-room reflections, array splay/taper modelling and processor configuration. Soundvision (L-Acoustics), ArrayCalc (d&b), K-array proprietary, EASE Focus (generic) — all output per-seat SPL maps, frequency-response per seat, sub-array steering and amplifier deployment plans. Use the calculator on this page for first-order scoping; specify the brand's prediction software output as a project deliverable from your integrator. The two tools are sequential, not redundant.

v1 deliberately limits to 7 brands with broad professional-AV coverage — K-array, KGEAR, JBL Professional, d&b audiotechnik, L-Acoustics, Fonestar and Ecler. Kasper Sound and other domestic / international brands are not in v1 pending verified datasheet collection. We will not commit half-verified data — the trust the calculator exists to build degrades the moment a single spec is approximated. Send brand and model spec via /contact; verified additions land in editorial batches.