Focal SUB 10 Car Subwoofer

Focal SUB 10 is a passive 25 cm car subwoofer designed for a separately configured audio system. It has a single voice coil and a nominal impedance of 4 Ω. The driver can be installed in either a sealed or bass-reflex enclosure.

The package contains one speaker. This is not a complete subwoofer enclosure with a built-in amplifier. Installation requires a suitable enclosure, an external amplifier and speaker cable.

Who this subwoofer is for

This model is intended for a car audio system in which the low-frequency section is designed separately. This approach allows the enclosure type and amplifier to be selected according to the space available in the vehicle. The passive design also gives the installer control over amplification and system tuning.

The 25 cm designation refers to the nominal 10-inch speaker class. It does not specify the required mounting cut-out or installation depth. Before building an enclosure, measure the actual driver and allow sufficient clearance for its terminals.

Choosing an enclosure

A sealed enclosure can have a volume starting at 10 litres. Because it does not need a bass-reflex port, it can be installed in a smaller enclosure. The cabinet must have strong, airtight joints, as air leaks will affect its operation.

A bass-reflex enclosure can have a volume starting at 25 litres. The port opening must have an unobstructed path for airflow. Its dimensions and tuning must be calculated for the chosen enclosure design.

These volumes are starting limits rather than complete enclosure plans. The space occupied by the speaker, internal bracing and the bass-reflex port must also be considered during the design process.

Cone, surround and magnetic system

The polypropylene cone is the moving part of the speaker that transfers low-frequency energy into the air. It is connected to the basket by a butyl surround. The surround allows the cone to move backwards and forwards while helping it remain correctly centred.

A ferrite magnet forms part of the magnetic system in which the voice coil moves. These details must not be replaced with specifications from another SUB 10 variant. The SUB 10 Slim is a separate model with different parameters.

Connection and amplifier selection

Speaker cable is connected through the screw terminals. Tighten the connections securely and maintain consistent polarity throughout the system. Reversed polarity can weaken bass reproduction when the subwoofer plays together with the other speakers.

One driver presents the amplifier with a nominal 4 Ω load. The amplifier must operate reliably at this impedance. Connecting multiple drivers changes the total load, so the wiring arrangement must remain within the amplifier’s operating capabilities.

The speaker itself has no amplifier controls. Gain, the low-pass filter and phase are adjusted on the external amplifier or audio processor. Begin with a low gain setting and increase it while listening carefully, keeping the system free from audible distortion.

Understanding the power and sensitivity figures

The 250 W RMS nominal power rating is the main reference for amplifier selection and system adjustment. The 500 W maximum rating does not describe continuous operation. An amplifier should therefore not be selected solely by comparing maximum-power figures.

The 85 dB sensitivity rating was measured using 2.83 V at a distance of one metre. It is meaningful to compare this figure only with speakers measured under the same conditions. In a vehicle, the final result is also affected by the enclosure, amplifier and cabin acoustics.

Tuning and positioning in the vehicle

The enclosure must be secured firmly so that it cannot move while the vehicle is being driven. Luggage and trim panels must not obstruct the cone or the bass-reflex opening. Enclosure placement will also affect how bass is distributed throughout the passenger compartment.

Begin low-pass filter adjustment with reference to the lower reproduction limit of the main speakers. Setting the crossover too high can make the location of the bass source more noticeable. If the amplifier provides phase adjustment, compare the available settings while listening from the driver’s seat.

System compatibility

The manufacturer states that this model is compatible with all Focal Car Audio products. It is particularly recommended for Auditor, Access, Universal, Polyglass and Slatefiber systems. The amplifier load and enclosure design must still be selected separately for the installation.

Technical specifications

FAQ

Is this a complete subwoofer enclosure?

No. It is a single passive speaker that requires a separate enclosure and external amplifier. The enclosure type can be chosen to suit the installation space and the intended system design.

Which enclosure should I choose?

A sealed enclosure takes up less space and does not require a bass-reflex port. A bass-reflex design needs a larger volume and a port that has been accurately designed and tuned.

How do I connect the speaker?

Connect the speaker cable to the terminals and tighten it securely. Maintain matching positive and negative polarity at both the amplifier and speaker ends.

What kind of amplifier should I choose?

The amplifier must operate reliably with the nominal load shown in the specification table. Use the RMS rating as the main power reference rather than relying only on the maximum-power figure.

How should I set the gain?

Start with the gain set low. Increase it gradually until the bass integrates with the main speakers without audible distortion.

Can I use two of these subwoofers?

Each speaker is sold separately. Connecting multiple units changes the load presented to the amplifier. Do not choose series or parallel wiring without first checking the amplifier’s permitted operating limits.

Is this model intended for a home stereo or cinema system?

No. It is designed for a car audio system. Compatibility is specified for Focal Car Audio products, so home audio use is not the intended application for this model.