Helix W8 Competition (1x4 Ohm)
8″ subwoofer · 4 Ω · 250 W RMS
The Helix W8 Competition (1x4 Ohm) is a 8″ subwoofer. With Qts 0.25 and EBP 154 it suits a ported box: deeper and louder; sealed, the bass sounds a bit dry. Modest excursion (Xmax 0.24″) — for clean sound at moderate levels, not for SPL competitions.
| Source | web.archive.org · manufacturer data |
|---|---|
| Checked against source | October 2026 |
| Thiele/Small parameters | complete |
| Mounting dimensions | 1 of 4 — missing: cutout, frame outer diameter, magnet diameter; the designer will use an estimate |
Recommended box
For a sedan, one sub, 250 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
smaller, tighter| Bass character (Qtc) | Dry and tight · 0.46 |
|---|---|
| Fc | 76 Hz |
| F3 (−3 dB, no cabin gain) | 135 Hz |
| Example box (outside) | 10 5/8″ × 10 5/8″ × 7 7/8″ |
Ported
deeper, louder| Tuning (Fb) | 41 Hz |
|---|---|
| Port | 2 round ports Ø3″, 21 1/4″ long |
| Port velocity at 250 W | 72 ft/s |
| F3 (−3 dB, no cabin gain) | 117 Hz |
| Example box (outside) | 28″ × 15 3/4″ × 6 7/8″ |
Deeper: 0.64 ft³ (18 L) tuned to 42 Hz, 14 1/16″ × 15 3/4″ × 11 5/8″ outside — a bigger box with flatter deep bass. Open in the calculator
Projects with this subwoofer
Boxes that users designed and published: plans, cut sheet and response graph.
Thiele/Small parameters
| Size | 8″ |
|---|---|
| Voice coils | 4 Ω |
| RMS power | 250 W |
| Fs | 41.6 Hz |
| Qts | 0.25 |
| Qes | 0.27 |
| Qms | 4.2 |
| Vas | 0.65 ft³ |
| Re | 3.5 Ω |
|---|---|
| Sd | 32.6 in² |
| Xmax | 0.24″ |
| Vd | 7.7 in³ calc. |
| Mms | 50 g calc. |
| BL | 13 T·m calc. |
| EBP | 154 — suits ported calc. |
| Sensitivity, 1 W / 1 m | 88.9 dB calc. |
Mounting dimensions
| Cutout diameter | ≈ 7 5/16″ |
|---|---|
| Mounting depth | 4 7/16″ |
Where it fits in a vehicle
Spots from our vehicle guides where the cutout, mounting depth and recommended box fit. The spot sizes are approximate — measure your own vehicle.
- F-150 SuperCrew — under the rear seat sealed and ported box
- F-150 regular cab — behind the seat sealed and ported box
- Ram Crew Cab — under the rear seat sealed and ported box
- Ram regular cab — behind the seat sealed and ported box
- Tacoma Double Cab — under the rear seat sealed and ported box
- Tacoma Access Cab — behind the front seats sealed and ported box
- Bronco 4-door — behind the rear seat sealed and ported box
- Wrangler 4-door, hard top — behind the rear seat sealed and ported box
- Wrangler 4-door, soft top — behind the rear seat sealed and ported box
- Silverado / Sierra Crew Cab — under the rear seat sealed and ported box
- Silverado / Sierra regular cab — behind the seat sealed and ported box
- Spare tire well sealed box
- Polaris RZR / Ranger — under the seat sealed box
- Can-Am — under the seat sealed box
- Avalanche — under the rear seat sealed and ported box
- FJ Cruiser — behind the rear seat sealed and ported box
- El Camino 1978–87 — behind the seat sealed and ported box
- Cherokee XJ — cargo area, spare moved out sealed and ported box
- Excursion — behind the third row sealed and ported box
- Mustang 2015–2023 coupe — trunk sealed and ported box
- Challenger / Charger — trunk sealed and ported box
- Tesla Model 3 — well under the trunk floor sealed and ported box
- Club Car Precedent — under the rear seat sealed and ported box
Cone area (Sd) calculated from Fs, Vas and Mms: 32.7 in².
“≈” 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
- web.archive.org/web/20060311214447/http://www.audiotec-fischer.com/pdfs/Woofer_W
- web.archive.org/web/20060311213645/http://www.audiotec-fischer.com/pdfs/HelixPro
- web.archive.org/web/20061016233435/http://www.audiotec-fischer.com/pdfs/Helix%20
Other Helix 8″ models
- Helix IK S8-DVC2 (2x2 Ohm) 8″ · dual 2 Ω
- Helix IK S8-SVC2 (1x2 Ohm) 8″ · 2 Ω
- Helix IK W8-DVC2 (2x2 Ohm) 8″ · dual 2 Ω
- Helix IK W8-SVC2 (1x2 Ohm) 8″ · 2 Ω
- Helix IQ W8-DVC2 (2x2 Ohm) 8″ · dual 2 Ω
- Helix K 8W-SVC2 (1x2 Ohm) 8″ · 2 Ω
Similar 8″ subwoofers from other brands
Close in Fs, Qts and Vas — a box of similar volume will suit them.
- JBL Stage 810 0.28 ft³ sealed · 0.95 ft³ ported
- Lanzar MAX8 0.32 ft³ sealed · 0.99 ft³ ported
- Audio System X08 EVO 0.28 ft³ sealed · 0.95 ft³ ported
- Orion Cobalt 8 DVC (1999) 0.28 ft³ sealed · 0.92 ft³ ported
- Morel Ultimo 802 (SVC 2 ohm) 0.35 ft³ sealed · 0.60 ft³ ported
- Gladen RS 08 EXTREME (SVC 2 ohm) 0.32 ft³ sealed · 1.02 ft³ ported
FAQ
What box does the Helix W8 Competition (1x4 Ohm) need?
Recommended net volume: 0.28 ft³ sealed, 0.95 ft³ ported tuned to 41 Hz — for one sub in a sedan at 250 W. Fit the box to your space and amp in the free calculator, with plans and a cut sheet.
What are the Helix W8 Competition (1x4 Ohm) Thiele/Small specs?
Fs 41.6 Hz, Qts 0.25, Vas 0.65 ft³, Xmax 0.24″, Sd 32.6 in².
What is the Helix W8 Competition (1x4 Ohm) mounting depth?
Mounting depth is 4 7/16″. The inside depth of the box must exceed the mounting depth by at least 1″.
How much power does the Helix W8 Competition (1x4 Ohm) handle and how do I wire it?
RMS power rating: 250 W. Wiring for several subs and amp power — in the wiring calculator.
Is the Helix W8 Competition (1x4 Ohm) better sealed or ported?
EBP 154: a ported box (0.95 ft³, tuned to 41 Hz) suits it best — deeper and louder. Sealed (0.28 ft³) the bass is drier.
What port does the Helix W8 Competition (1x4 Ohm) need?
For the 0.95 ft³ ported box tuned to 41 Hz: 2 round ports Ø3″, 21 1/4″ long, area 14.1 in²; or a round port Ø4 1/4″, ≈ 20 3/8″ long. Port air speed at 250 W: 72 ft/s.
What box do two Helix W8 Competition (1x4 Ohm) subs need?
Two subs need twice the volume: 0.57 ft³ sealed, or 1.91 ft³ ported at the same 41 Hz tuning with twice the port area. One shared chamber or one per sub — whatever fits your vehicle.