Helix CB C87.2-S3 – 3.5″ (87 mm) 2-way coaxial speaker

The Helix CB C87.2-S3 is a 2-way coaxial speaker system with a 87 mm (3.4″) midrange and a 13 mm PEI dome tweeter from the BASIC series of the HELIX COMPOSE platform. COMPOSE was created by reworking proven universal speakers to meet the demands of modern vehicles, combining the flexibility of universal designs with the fit of vehicle-specific systems under the motto “developed inside the vehicle, for the vehicle”. BASIC is the entry point into the COMPOSE range and is designed to be driven by HELIX and MATCH amplifiers.

Its 3 Ω design is tuned to match HELIX and MATCH amplifiers, increasing efficiency and maximum sound pressure. The midrange combines a lightweight yet stiff injected polypropylene cone with a ventilated steel basket, a powerful magnet system and a soft polyurethane dustcap for a refined upper midrange, while the tweeter uses a lightweight PEI dome driven by a highly efficient neodymium magnet. An integrated 6 dB high-pass crossover and a compact construction make it suited to tight installation spaces.

Key Features

2-way coaxial system: combines high efficiency with strong sound performance in a single speaker
3 Ω technology: gets the maximum power output from the amplifier, especially with HELIX and MATCH amplifiers
Compact design: makes installation easier in cramped mounting locations
13 mm PEI dome tweeter: provides accurate, detailed treble
Neodymium tweeter magnet: highly efficient, with high magnetic flux linearity
87 mm (3.4″) midrange: lightweight injected polypropylene cone with the stiffness needed for good sound
Ventilated steel basket: sturdy basket with additional ventilation holes for voice coil cooling and high power handling
Powerful magnet system: optimises impulse response of the midrange
Polyurethane dustcap: soft dustcap that optimises the upper-midrange response
Integrated crossover: built-in 6 dB high-pass for the tweeter

Drivers & Construction

Tweeter: 13 mm PEI dome, neodymium magnet, 13 mm voice coil
Midrange: 87 mm (3.4″), injected polypropylene cone, 25 mm voice coil (winding height 8.3 mm), steel basket with ventilation holes, soft polyurethane dustcap

Acoustic Performance

Power handling: 40 W RMS / 60 W max.
Impedance: 3 Ω (DC resistance Re 3.0 Ω)
Sensitivity: 88 dB @ 2.83 V / 1 m; 84 dB @ 1 W / 1 m
Frequency response: 110 Hz – 22,000 Hz
T/S parameters (midrange): Fs 92 Hz, Qms 3.80, Qes 0.74, Qts 0.62, Vas 1.5 l, Cms 820 µm/N, Bl 2.9 Tm, Sd 36 cm², Mms 3.6 g, Rms 0.52 kg/s
Max. linear excursion (Xmax): ±2.2 mm

Crossover

Type: integrated in the speaker
Slope: 6 dB high-pass for the tweeter

Installation Notes

Outer diameter: 86.9 mm / 3.43″
Installation diameter: 79.0 mm / 3.11″
Installation depth: 42.0 mm / 1.65″
Compact design: intended to simplify installation in tight spaces

Technical Specifications

Power handling RMS / Max.	P	40 / 60 Watts
Frequency response		110 Hz – 22,000 Hz
Impedance	Z	3 Ω
Sensitivity	SPL	88 dB @ 2.83V / 1m 84 dB @ 1W / 1m
Outer diameter	ø	86.9 mm / 3.43”
Installation diameter	ø	79.0 mm / 3.11”
Installation depth		42.0 mm / 1.65”

Midrange
Impedance	Z	3 Ω
DC resistance	Re	3.0 Ω
Resonance frequency	Fs	92 Hz
Mechanical Q factor	Qms	3.80
Electrical Q factor	Qes	0.74
Total Q factor	Qts	0.62
Compliance	Cms	820 μm/N
Equivalent air volume	Vas	1.5 L
Force factor	Bl*	2.9 Tm
Cone area	Sd	36 cm²
Moving mass	Mms	3.6 g
Mechanical resistance	Rms	0.52 kg/s
Voice coil diameter	ø	25 mm
Voice coil winding height		8.3 mm
Max. linear excursion	Xmax	+/- 2.2 mm

Tweeter
Voice coil diameter	ø	13 mm

Features
Tweeter		PEI dome and neodymium magnet
Midbass		Injected polypropylene cone
Crossover		Integrated, 6 dB highpass

Scope of Delivery

2 x CB C87.2-S3
1 x Mounting material

8.7 cm (3.5″)

Manufacturer

Dimensions cm (inch)

Impedance (Ohm)

Type

Helix CB C87.2-S3

Ground Zero GZCS 8.7CX