Desk Reflections
Early reflections from the desk, console and screen comb-filter the midrange before the room gets a say.
Related
A vocal sounds dull in the midrange and a snare rim click seems squashed; move the speakers to the other side of the desk and the problem follows the desk. The desktop, the console surface and the screen are the three reflectors people forget, and all three sit close enough that their reflections arrive almost with the direct sound.
A path difference of centimetres
The extra distance the reflection travels sets the first notch, at roughly the speed of sound divided by twice that difference. An extra 0.2 m puts the notch near 860 Hz; 0.4 m brings it to 430 Hz. Shorter paths push the notch up into the region where voices and snares live. The result is a comb of evenly spaced notches, not a smooth roll-off.
What each surface does
| Surface | Typical path difference | First notch | Symptom | Treatment |
|---|---|---|---|---|
| Desktop | 0.15–0.30 m | 570–1140 Hz | Nasal voice, hard acoustic guitar | Angle it or add a pad |
| Console top | 0.10–0.25 m | 690–1700 Hz | Midrange grit | Break up the flat area |
| Screen | 0.20–0.35 m | 490–860 Hz | Soft centre image | Move back and down |
| Near side wall | 0.30–0.60 m | 290–570 Hz | Unnatural width | Symmetrical absorption |
Fixing the desk, not the speaker
Raise the monitors on stands so the front edge sits level with or slightly above the desktop, which keeps the desk reflection out of the listening axis. If the desk has to stay, lay an absorbent pad on the desk between speaker and listener, right on the reflection point. An angled console beats a flat one; push the screen back and lower it so its reflection lands behind your head. Keep every change symmetrical or the image will shift.
A reflection is not a driver fault
When the same pair behaves differently on two desks, the desk is the variable. Nearfield monitoring raises the ratio of direct to reflected sound, but the desk path is so short that proximity does not remove it. EQ rarely helps, because the notch comes from a time difference rather than a tilted response. The quick test: lift the speakers thirty centimetres and listen again; if the dip moves or disappears, the desk caused it.
Listen in the library
All tracks from midicn-lib — inline badge is the license tier (C1 commercial / C2 non-commercial / C3 study only).
Along the same line
Sources
- Everest, F. Alton，Master Handbook of Acoustics（McGraw-Hill）— 早期反射与梳状滤波
- Newell, Philip，Recording Studio Design（Focal Press）— 控制室台面与调音台反射
- Genelec，Monitor Setup Guide（厂商文档）— 桌面摆放与声学处理建议