Control Room
B311 — Audio mixing and monitoring — The critical listening environment
Use Cases
Audio mixing, monitoring, quality control, client review sessions. This is where all recorded content is evaluated and mixed to final output.
Requires NC-18 and calibrated stereo monitoring with Genelec 8030C speakers at ±30°.
Room Data
| Parameter | Value |
|---|---|
| Room code | B311 |
| Width | N 293.5 / S 213.6 cm |
| Depth | 270 cm |
| Area | 6.97 m² |
| Volume | 19.17 m³ |
| Ceiling AFF | 275 cm (28% Rockfon cloud) (28% = 1.95 m² of 6.97 m² floor area, centered above listening position) |
| Flooring | Carpet |
| NC target | NC-18 |
| RT60 achieved | 0.307s |
| Schroeder freq | 253 Hz |
| IDU | IDU-03 (dedicated; former Editing branch capped) |
Floor Plan Position
Control Room sits south of VO Live, west of the buffer spine. Room footprint is a trapezoid — north 293.5 cm, south 213.6 cm, depth 270 cm (west wall diagonal). A new external entry door D5 (STC 50, 90×220, opens out) is set in the south perimeter wall.
Column COL_W at (369.1, 140.6) passes through this zone with a 10mm air gap maintained around it.
Room Footprint
Acoustic Treatment
| Element | Qty | Specification |
|---|---|---|
| Absorption panels | 3 [AC] | First-reflection side walls — cannot be removed or moved |
| Corner bass traps | 3 | Rockwool RWA45 150mm, 300mm corner, full-height floor-to-ceiling |
| Soffit trap | 1 | Above D3 door head, NE (serves the corner blocked by the door; SE carries a full corner trap) |
| 125Hz membrane traps | 3 | 4mm ply + 100mm cavity + 50mm RWA45, 1200×600, f0≈123Hz (South ×2, West ×1) |
| QRD diffusers | 2 | Rear wall |
| Ceiling | 28% | Rockfon cloud (partial coverage) |
| Ceiling cloud | 1 [AC] | 200x120cm suspended cloud, centered over mix position at 245cm AFF. 50mm Rockwool RWA45 in fabric-wrapped frame. Reduces first ceiling reflections at the listening position. |
Monitor Setup
| Parameter | Value |
|---|---|
| Monitors | Genelec 8030C L+R |
| Angle | ±30° stereo triangle |
| Listening position | 1.54m from front wall (57% of 2.70m clear depth — equilateral triangle governs) |
38% Rule — Mix Position Geometry
Optimal listening position = 38% of room depth from speaker wall = 0.38 x 270cm = 102.6cm.
Stereo triangle: speakers at ±30° = 1.54m separation at 1.33m distance.
SBIR Warning: Side-wall proximity creates a cancellation notch near 90 Hz. The 2 first-reflection panels on side walls are mandatory to manage this.
Optimal listening position = 38% of room depth from speaker wall = 0.38 x 270cm = 102.6cm.
Stereo triangle: speakers at ±30° = 1.54m separation at 1.33m distance.
SBIR Warning: Side-wall proximity creates a cancellation notch near 90 Hz. The 2 first-reflection panels on side walls are mandatory to manage this.
RT60 Analysis
| Band | Target (s) | Achieved (s) | Status |
|---|---|---|---|
| 125 Hz | 0.40 | 0.23 | ✓ Pass |
| 250 Hz | 0.38 | 0.24 | ✓ Pass |
| 500 Hz | 0.35 | 0.24 | ✓ Pass |
| 1 kHz | 0.33 | 0.22 | ✓ Pass |
| 2 kHz | 0.33 | 0.21 | ✓ Pass |
| 4 kHz | 0.33 | 0.20 | ✓ Pass |
Room Modes
| Mode | Frequency |
|---|---|
| Length (L) | 63.5 Hz |
| Width (W) | 66.5 Hz |
| Height (H) | 62.4 Hz |
| Schroeder | 253 Hz |
62–67 Hz Modal Congestion Warning
The three fundamental axial modes cluster tightly — Length 63.5 Hz, Width 66.5 Hz, Height 62.4 Hz — all within a 4 Hz band. This congestion causes phantom bass buildup at the mix position. Membrane absorbers tuned to ~63 Hz plus full-height corner traps manage this resonance.
Schroeder frequency: 253 Hz — modal behavior dominates below this frequency.
The three fundamental axial modes cluster tightly — Length 63.5 Hz, Width 66.5 Hz, Height 62.4 Hz — all within a 4 Hz band. This congestion causes phantom bass buildup at the mix position. Membrane absorbers tuned to ~63 Hz plus full-height corner traps manage this resonance.
Schroeder frequency: 253 Hz — modal behavior dominates below this frequency.
Noise Criteria
Target: NC-18
| Octave (Hz) | 63 | 125 | 250 | 500 | 1k | 2k | 4k | 8k |
|---|---|---|---|---|---|---|---|---|
| NC-18 limit (dB) | 54 | 44 | 37 | 31 | 27 | 24 | 22 | 21 |
Boundary Build-ups
| Wall | Type | Lab STC | Field | Assembly |
|---|---|---|---|---|
| North (W6) | Partition (NEW BUILD) | 53 | 47–51 | NEW-BUILD VO/Control partition at y=280 (obs. window OW-1) |
| South perimeter | Gypsum stud (existing) | ~50 | 44–48 | Existing gypsum partition lined/rebuilt to STC 50 class (PW-03); D5 external door hosted here as a FRAMED opening on a steel subframe — no concrete cutting, no lintel |
| East (W5) | Buffer spine (NEW BUILD) | 55 | 49–53 | NEW-BUILD double leaf (W-07): 2×12.5mm gyp+GG + 100mm studs+RW + 2×12.5mm gyp+GG |
| West (W2) | Existing gypsum diagonal + NEW inner leaf | ~60 (class) | 55–60 | Existing gypsum wall (kept, NO fixings into it) + ≥25mm air gap + independent 70mm stud leaf w/ RWA45 + 2×12.5 SoundBloc + GG (PW-02) |
| Ceiling | Rockfon cloud | — | — | 28% coverage, 275cm AFF |
| Floor | Float | — | — | Carpet finish + 15cm Sylomer buildup |
HVAC
| Parameter | Value |
|---|---|
| IDU | IDU-03 (dedicated; B2 silencer RETAINED + re-rated for Control — BOQ HV-02; the capped item is the orphan east-zone spur, BOQ HV-01) |
| Trunk silencer | Run B: 1000mm, 25dB |
| Branch silencer | Run B1: 500mm, 15dB (Control branch) |
Design Constraints [AC]
- [AC] First-reflection panels (3 panels) — cannot be removed or moved
- [AC] New external entry door D5 (STC 50, 90×220) in south perimeter wall — opens OUT
- [AC] Observation window OW-1 into VO Live on north wall, sill 110cm AFF, 5° tilt
- [AC] COL_W at (369.1, 140.6) passes through this zone — 10mm air gap maintained
- Custom production desk (room tapers 213.6 south → 293.5 north; a 160cm desk leaves 54–134cm clearance). L-shaped: main wing 160×75cm + return wing 90×60cm + raised monitor shelf +20cm. Steel frame + birch plywood. Full build spec in project documentation.