Sine Design

GRS 4FR-8

fullrange · EBP 163 → suits a ported box · nominal (full) — GRS datasheet (https://www.parts-express.com/pedocs/specs/GRS%20Spec%20Sheets/292-434--grs-4fr-8-spec-sheet.pdf)

Thiele/Small parameters

Fs (resonance)127 Hz
Qts0.7
Qes / Qms0.78 / 6.71
Vas1.7 L
Re / nominal Z6.9 Ω / 8 Ω
Xmax1.0 mm
Sensitivity88.3 dB (1 W/1 m, calc); 89 dB (2.83 V/1 m, mfr)
Power handling15 W

Published (nominal) values, params full — verify by measurement (DATS/REW) before building.

Datasheet (PDF) ↗ — manufacturer-hosted

Recommended enclosures

Sealed (Qtc 0.707) — Vb84.6 L
Sealed — Fc / F3128.3 / 128.3 Hz
Ported (suggested) — Vb10.5 L
Ported — Fb / F372.3 / 62.9 Hz
Open in designer →Use my measured parameters →Buy at Parts Express →

Affiliate disclosure: some links are affiliate links and we may earn a commission on qualifying purchases at no extra cost to you. Prices are estimates at the time of writing; verify on the retailer's site.

About this driver

The GRS 4FR-8 is a 4.5″ fullrange with a free-air resonance of 127 Hz and a total Q (Qts) of 0.7. Its efficiency-bandwidth product (EBP) of 163 points toward a ported alignment. In a 84.6 L sealed box it reaches an F3 of 128.3 Hz (Qtc 0.707); a suggested 10.5 L box tuned to 72.3 Hz extends to about 62.9 Hz. See the sealed vs ported guide for how to choose.

Recommended partners

modeled estimate

The tweeters below pair well with the GRS 4FR-8 in a two-way design — each grade is a modeled estimate of the crossover match, with a suggested crossover point. Open any pair in the guided builder to design the crossover and total the parts.

Modeled estimate from T/S + geometry — no measurements. The verdict is robust; it improves with measured FRD/ZMA data.

Related fullranges