Helix Ci5 S200FM-D2 – 200 mm shallow hybrid woofer with 2 x 2 Ω dual voice coil
The Ci5 S200FM-D2 belongs to the HELIX COMPOSE i5 series, which sits between the i7 and i3 lines and targets a genuine hi-fi experience in the car. As part of the COMPOSE platform it adapts a universal driver to modern vehicles, with impedances matched to HELIX and MATCH amplifiers.
It is a hybrid design that works both as a mid-woofer and as a subwoofer, combining high excursion, power handling and output with an installation depth of just 47 mm. This makes it suitable for BMW under-seat positions and Mercedes bulkhead (footwell) locations. The glass-sphere-reinforced polymer basket provides stability, low self-resonance, reduced flux modulation and heat resistance, and car-specific FlexMount200 adaptor rings allow fitting in original positions.
Key Features
- High excursion: ±7.5 mm linear excursion for high SPL and strong low-frequency output.
- Hybrid concept: covers roughly 25–500 Hz, bridging subwoofer and mid-woofer duties.
- Dual 2 Ω voice coil: flexible wiring for mono, two-channel or multichannel amplifiers.
- Shallow build: only 47 mm installation depth for tight spaces.
- Compact outer diameter: same cone area as typical 200 mm woofers.
- Polypropylene cone: light yet stiff injected PP cone.
- Reinforced polymer basket: glass-bead composite for rigidity and reduced ringing.
- Powerful magnet system: high efficiency and good impulse response.
- Vehicle applications: suited to BMW under-seat installation and front-subwoofer use in Mercedes.
- FlexMount200: car-specific adaptors for acoustically optimised integration.
Drivers & Construction
200 mm flat woofer with injected polypropylene cone (194 cm² cone area), 38 mm dual voice coil with 20 mm winding height, powerful magnet system and glass-bead-reinforced polymer basket. Also available as single-voice-coil version Ci5 S200FM-S2 (1 x 2 Ω).
Acoustic Performance
Power handling 200 W RMS / 400 W max, impedance 2 x 2 Ω (Re 3.6 Ω), frequency response 25–500 Hz, sensitivity 90 dB at 2.83 V/1 m (87 dB at 1 W/1 m). Thiele-Small data: Fs 55 Hz, Qms 8.31, Qes 0.88, Qts 0.80, Cms 256 µm/N, Vas 13.5 l, BL 6.7 Tm, Mms 32 g, Rms 1.39 kg/s, Xmax ±7.5 mm.
Installation Notes
Outer diameter 195 mm (7.68″), installation diameter 173.5 mm (6.83″), installation depth 47.0 mm (1.85″). Use the vehicle-specific FlexMount200 adaptors for original under-seat and bulkhead positions.
Technical Specifications
| Power handling RMS / Max. | P |
200 / 400 Watts |
| Impedance | Z | 2 x 2 Ω |
| DC resistance | Re | 3.6 Ω |
| Frequency response | 25 Hz – 500 Hz | |
| Resonance frequency | Fs | 55 Hz |
| Mechanical Q factor | Qms | 8.31 |
| Electrical Q factor | Qes | 0.88 |
| Total Q factor | Qts | 0.80 |
| Compliance | Cms | 256 µm/N |
| Equivalent air volume | Vas | 13.5 L |
| Force factor | B*I | 6.7 Tm |
| Sensitivity | SPL | 90 dB @ 2.83 V / 1m 87 dB @ 1W / 1m |
| Cone area | Sd | 194 cm² |
| Moving mass | Mms | 32 g |
| Cone material | Injected polypropylene | |
| Mechanical resistance | Rms | 1.39 kg/s |
| Voice coil diameter | ø | 38 mm |
| Voice coil winding height | 20 mm | |
| Max. linear excursion | Xmax | +/- 7.5 mm |
| Outer diameter | ø | 195 mm / 7.68″ |
| Installation diameter | ø | 173.5 mm / 6.83″ |
| Installation depth | 47.0 mm / 1.85″ | |
| Features | FlexMount200 |
Scope of Delivery
2 x Ci5 S200FM-D2
2 x Mounting material
