S3 Layout Re-split

The four-room split forced the east zone into a cramped 11.23 m² video studio and a small 8.56 m² editing suite, separated by an internal partition (Wall 7) and its door (D4). Editing is a quiet, non-critical activity (the old NC-25 target) that does not need a dedicated acoustically-isolated room — it can be performed at any workstation, including inside the Control Room or Video/Podcast space. Dedicating an isolated room to it wasted the most valuable floor area in the facility.

Removing the Editing Suite lets the entire east zone become a single Video/Podcast room of 19.78 m². Freed of the internal Wall 7 / D4 partition, the room also gains a high 3.40 m clear ceiling. A Rev2 laser survey found the true slab-to-slab at 366.4 cm — not the 340 cm assumed on the old drawings — so the height chain is now measured, not estimated: 366.4 slab − 15 cm floated floor − 11 cm compact decoupled ceiling leaf = 340 cm clear, with the hanging MEP (HVAC unit and black pipe) boxed into a perimeter bulkhead with an HVAC service hatch. The larger volume (67.3 m³) pushes the Schroeder frequency down to 120–140 Hz (state-dependent) and spreads the room modes more evenly, giving a well-behaved, flexible space for multi-camera video, podcast panels, and small live sessions. Two weak partition elements (Wall 7 and door D4) are eliminated entirely.

Backdrop — the HYBRID stack (Study B fork, owner decision 2026-08-06). Version A (acoustics5) resolved the backdrop as a curtain-only system (motorised interchangeable-fabric backdrop). Study B forks that decision into a hybrid: Layer 1 is a hard cove cyclorama — raft-mounted independent framing (never fixed through the isolation leaves), Knauf 12.5 mm flats + Knauf Herform flexible-board coves, finished in Rosco Chroma Key Green #5711 with Roscoflamex PA additive (ASTM E84 Class A route) — wrapping the North wall (full 479) plus the East wall north-half (206) around the NE corner. Layer 2 is a pair of motorised curtain tracks in front of the cyc: WHITE heavyweight molton ≥300 g/m² IFR at ~25 cm and BLACK molton/velour ≥300 g/m² IFR at ~35 cm off the cyc face, slab-hung on isolated neoprene hangers. A Rosco Chroma Floor ramped sweep sits at the cyc base. Green is ONLY the painted cyc — there is no green curtain. The trade is deliberate: the hard cyc gives a broadcast-grade key AND a live music state (S1, RT 0.332 s — choir/instruments), while the deployed curtains return the room to curtain-class speech absorption (S2/S3, 0.242 s). The S1 250 Hz build-up is cured by 2× BT-08 membranes retuned ~250 Hz; upsizing the ceiling clouds to 40% was rejected because it kills the S1 music floor.

In the four-room layout the Control Room was reached only through the buffer spine or from VO Live (D3). With the east-zone re-split and the removal of the old Editing access, the Control Room needed its own external entry so engineers can come and go without transiting VO Live or the buffer during a take. (The old buffer↔Control door D2 has since been deleted in Rev2 — Control is now entered only by external D5.)

D5 is a new STC 50 acoustic door (90 × 220 cm) on the south wall. It matches the STC 50 perimeter-shell/entry standard (same as D1), so it introduces no weak link in the envelope. It opens outward for clean egress and to avoid any swing conflict with the console and the side-wall first-reflection panels inside the room. Routing Control traffic through its own door reduces footfall-borne disturbance in VO Live and the buffer spine during recording.

A corners-only Control Room treatment — bass traps in all corners, QRD diffusers on the rear wall, ceiling cloud — would meet the RT60 target of 0.30s without any flat absorption panels on the side walls. The RT60 number would be correct. However, RT60 does not capture early reflections.

In a nearfield monitoring environment, the primary acoustic concern after RT60 is the first reflection points — the spots on the left and right walls where direct sound from the monitors bounces once before reaching the mix position. Untreated, these reflections arrive 5–15 ms after the direct sound, causing comb filtering that colours the frequency response and compromises stereo imaging. This is audible on every mix as a smeared centre image and unreliable low-mid decisions.

Three panels — at the first reflection points on the east and west side walls (~120 cm AFF, positioned by mirror method from the mix position) plus an absorptive/splayed front — eliminate this artefact without over-damping the room. The room is too small for a time-based reflection-free zone (ITDG under 15 ms), so the RFZ is achieved by absorbing the E/W first-reflection points directly. The resulting mid-band RT60 of approximately 0.307s sits in the preferred range for broadcast monitoring. Heavier flat absorption was rejected: it would over-damp the larger 6.97 m² Control Room and lose the natural reverb tail needed for mixing judgment.