Audio System R08 FLAT EVO3-D4
8″ subwoofer · dual 4 Ω · 200 W RMS
Fs 59 HzQts 0.47Vas 0.27 ft³Xmax 0.49″
The published specs don’t add up:
- Fs, Vas and Sd don't match the moving mass of 45 g (they give 60 g) — one of the spec sheet values is probably wrong.
Recommended box
For a sedan, one sub, 200 W. It’s the same math as the designer’s step-by-step mode, where you can fit the box to your space, vehicle and amp and get plans, a cut sheet and DXF.
Sealed
| Net volume | 0.28 ft³ (8 L) |
|---|---|
| Qtc | 0.65 |
| Fc | 83 Hz |
| F3 (−3 dB, no cabin gain) | 94 Hz |
| Example box (outside) | 10 1/4″ × 10 1/4″ × 8 1/2″ |
Ported
| Net volume | 0.64 ft³ (18 L) |
|---|---|
| Tuning (Fb) | 47 Hz |
| Port | slot 1 15/16 × 14 5/16″, 49 5/16″ long |
| Port velocity at 200 W | 27 ft/s |
| F3 (−3 dB, no cabin gain) | 43 Hz |
| Example box (outside) | 31 1/2″ × 15 3/4″ × 8 1/16″ |
The volume and tuning are the recommendation, but the port doesn’t fit this example box. Size the box and port in the designer.
Open ported box in designerThiele/Small parameters
| Fs | 59 Hz |
|---|---|
| Qts | 0.47 |
| Qes | 0.51 |
| Qms | 5.58 |
| Vas | 0.27 ft³ |
| Re (one coil) | 3.6 Ω |
| Sd | 32.7 in² |
| Xmax | 0.49″ |
| Vd | 16.1 in³ calc. |
| Mms | 60 g calc. |
| BL | 12.5 T·m calc. |
| EBP | 116 — suits ported calc. |
| Sensitivity, 1 W / 1 m | 86.9 dB calc. |
General
| Size | 8″ |
|---|---|
| Voice coils | dual 4 Ω |
| RMS power | 200 W |
Mounting dimensions
| Cutout diameter | 7″ |
|---|---|
| Mounting depth | 3 1/4″ |
| Overall diameter | 8 7/16″ |
“≈” means the value isn’t in the spec sheet and a typical value for the size is used; “calc.” means it’s calculated from the published parameters. Check the manufacturer’s spec sheet before you build.
Data sources
- audio-system.de/wp-content/uploads/2025/03/Manual-R08-FLAT-EVO3-D4-1.pdf
- audio-system.de/produkte/subwoofer/radion-series/
Other Audio System 8″ models
- Audio System HX 08 SQ 8″ · 4 Ω
- Audio System R08 EVO 8″ · dual 4 Ω
- Audio System X08 EVO 8″ · dual 2 Ω