Soundstream R3.8
8″ subwoofer · dual 2 Ω · 700 W RMS
Fs 39.1 HzQts 1.15Vas 0.65 ft³
The published specs don’t add up:
- Fs, Vas and Sd don't match the moving mass of 134.9398 g (they give 59 g) — one of the spec sheet values is probably wrong.
Recommended box
For a sedan, one sub, 700 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 | 0.78 ft³ (22 L) |
|---|---|
| Qtc | 1.56 |
| Fc | 53 Hz |
| F3 (−3 dB, no cabin gain) | 38 Hz |
| Example box (outside) | 11″ × 11″ × 16 5/8″ |
Ported
| Net volume | 1.31 ft³ (37 L) |
|---|---|
| Tuning (Fb) | 41 Hz |
| Port | round port Ø2 1/2″, 4 1/4″ long |
| Port velocity at 700 W | 295 ft/s |
| F3 (−3 dB, no cabin gain) | 32 Hz |
| Example box (outside) | 27 1/2″ × 15 3/4″ × 7 11/16″ |
Thiele/Small parameters
| Fs | 39.1 Hz |
|---|---|
| Qts | 1.15 |
| Qes | 1.371 |
| Qms | 7.19 |
| Vas | 0.65 ft³ |
| Re (one coil) | 2.21 Ω |
| Sd | ≈ 33.3 in² |
| Xmax | ≈ 0.39″ |
| EBP | 28 — suits sealed calc. |
| Sensitivity, 1 W / 1 m | 81 dB calc. |
General
| Size | 8″ |
|---|---|
| Voice coils | dual 2 Ω |
| RMS power | 700 W |
Mounting dimensions
| Cutout diameter | 7 13/16″ |
|---|---|
| Mounting depth | 5 1/4″ |
“≈” 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.