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 (south) | 207 cm [AC] |
| Width (north) | 275 cm |
| Width (avg) | 241 cm |
| Depth | 225 cm |
| Area | 5.43 m² |
| Volume | 14.93 m³ |
| Ceiling AFF | 275 cm (60% Rockfon cloud) (60% = 3.30 m² of 5.43 m² floor area, centered above listening position) |
| Flooring | Carpet |
| NC target | NC-18 |
| RT60 achieved | 0.30s |
| Schroeder freq | 283 Hz |
| IDU | IDU-03 (shared with Editing) |
Floor Plan Position
Control Room sits south of VO Live, west of the buffer spine. The south wall width is 207 cm (not 210) — this is a locked SSOT value.
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 | 2 [AC] | First-reflection side walls — cannot be removed or moved |
| Bass traps | 4 | Rockwool RWA45 150mm, floor-to-ceiling, corners |
| QRD diffusers | 2 | Rear wall |
| Ceiling | 60% | 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 (68% depth) |
38% Rule — Mix Position Geometry
Optimal listening position = 38% of room depth from speaker wall = 0.38 x 225cm = 85.5cm.
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 225cm = 85.5cm.
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 | 0.42 | ✓ Pass |
| 250 Hz | 0.38 | 0.38 | ✓ Pass |
| 500 Hz | 0.35 | 0.34 | ✓ Pass |
| 1 kHz | 0.33 | 0.32 | ✓ Pass |
| 2 kHz | 0.33 | 0.31 | ✓ Pass |
| 4 kHz | 0.33 | 0.30 | ✓ Pass |
Room Modes
| Mode | Frequency |
|---|---|
| Length (L) | 76.2 Hz |
| Width (W) | 71.2 Hz |
| Height (H) | 62.4 Hz |
| Schroeder | 283 Hz |
62.4 Hz Double Mode Warning
Room width (275cm) equals ceiling height (275cm), creating a doubled axial mode at 62.4 Hz (f = 343 / (2 x 2.75) = 62.4 Hz). This causes phantom bass buildup at the mix position. A membrane absorber tuned to ~62 Hz on the south wall is recommended to manage this resonance.
Schroeder frequency: 283 Hz — modal behavior dominates below this frequency.
Room width (275cm) equals ceiling height (275cm), creating a doubled axial mode at 62.4 Hz (f = 343 / (2 x 2.75) = 62.4 Hz). This causes phantom bass buildup at the mix position. A membrane absorber tuned to ~62 Hz on the south wall is recommended to manage this resonance.
Schroeder frequency: 283 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 | 53 | 47–51 | VO/Control partition (obs. window OW-1) |
| South perimeter | Concrete | 65 | 58–62 | 300mm concrete + RSIC-1 + 50mm RW + 2×gyp |
| East (W5) | Buffer spine | 55 | 49–53 | 2×12.5mm gyp+GG + 100mm studs+RW + 2×12.5mm gyp+GG |
| West (W2) | Diagonal concrete | 65 | 58–62 | RSIC-V clips |
| Ceiling | Rockfon cloud | — | — | 60% coverage, 275cm AFF |
| Floor | Float | — | — | Carpet finish + 15cm Sylomer buildup |
HVAC
| Parameter | Value |
|---|---|
| IDU | IDU-03 (shared with Editing) |
| Trunk silencer | Run B: 1000mm, 25dB |
| Branch silencer | Run B1: 500mm, 15dB (Control branch) |
Design Constraints [AC]
- [AC] First-reflection panels (2 panels) — cannot be removed or moved
- [AC] Observation window OW-1 into VO Live on north wall, sill 100cm AFF, 5° tilt
- [AC] COL_W at (369.1, 140.6) passes through this zone — 10mm air gap maintained
- Custom production desk (207cm room width × 160cm desk = 47cm 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.