Planning
The P2 design uses four GRS 12SW-4HE drivers in a common roughly 350 L net chamber. The outer target is 2337 × 500 × 400 mm in 18 mm material. A central 100 × 300 mm port is folded inside the shallow enclosure.
Driver displacement, braces, rings and the port assembly are accounted for in the volume budget. Real part dimensions still have to be checked before cutting material.
Simulation
The linear model uses a roughly 20 Hz tuning and a protective 17 Hz fourth-order Butterworth high-pass as a planning case. Modelled excursion and port velocity remain below their chosen planning limits at the lower voltage case and approach them more closely at the higher case. Room gain and seat response are deliberately not invented.
Build
Real driver dimensions and displacement are checked first, followed by a dry assembly of braces and port before final bonding.
Measurements
Impedance, near-field response, REW measurements at several seats and phase/delay integration with LNGR IB-15.4 are planned.
Changes
P2 replaces the earlier two-GRS-18PT preview. Four GRS 12SW-4HE drivers now define the project while the 400 mm depth and 500 mm height remain fixed.
Result
The current result is a reproducible P2 planning package, not a finished subwoofer. Final extension, maximum output and room integration remain measurement tasks.