Focal Impulse 4.320 Amp Compact Digital 4 Channel Amplifier Class D 4x55w RMS
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The Focal Impulse 4.320 is a compact Class D 4-channel car amplifier delivering 55W RMS x 4 at 4 ohms, from Focal's Impulse range. Its small chassis fits almost anywhere in a vehicle, making it well suited to speaker upgrades or a 3-channel speaker-plus-subwoofer setup.
Key specifications
- Channels: 4 (3-channel and bridged modes possible)
- Power at 4 ohms: 55W RMS x 4
- Power at 2 ohms: 80W RMS x 4
- Bridged: 160W RMS x 2 at 4 ohms
- Amplifier class: Class D, CEA-2006 compliant
- Inputs: preamp and speaker-level
- Front filter: switchable 75Hz high-pass
- Rear filter: adjustable high- or low-pass (40–200Hz), phase 0–180°
- Dimensions: 6-15/16" W x 1-7/8" H x 2-5/8" D
Big power from a tiny amp
Focal designed the Impulse 4.320 to fit almost anywhere inside a vehicle. The chassis is smaller than a brick, yet delivers 55W RMS to each channel. In 3-channel mode it powers a pair of speakers at 55W RMS each while sending up to 160W to a subwoofer — a practical pairing with something like the Focal ISUB Active compact under-seat subwoofer.
Plays well with other stereos
The Impulse 4.320 includes input harnesses for connecting to any aftermarket receiver or factory radio. Separate filters for the front and rear channels let you optimise the sound for speakers and subs independently. The adjustable phase control on the rear channels helps blend a subwoofer with front speakers such as the Focal 165 AS Access Series 2-way 6.5" component speakers.
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Specification
| front channels | switchable high-pass filter (75 Hz) |
|---|---|
| for power wire shorter than 10 feet | 12-gauge power and ground leads and a 15A fuse recommended |
| dimensions | 6-15/16"W x 1-7/8"H x 2-5/8"D |
More specs
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What's Included
- 4-Channel amplifier
- 9" Power/speaker output harness
- Two 25A ATO fuses (one installed in in-line fuse holder)
- 8" Speaker input harness
- 7" RCA line input harness
- 2 Mounting brackets
- User Manual
Focal
About the Focal Impulse 4.320
From our tech experts at CEN
A Focal Impulse 4-channel amplifier, Class D, rated at 55w RMS.
Who it suits
Drivers who have upgraded their speakers and found the head unit cannot drive them properly. Impulse is Focal’s compact digital amplifier line.
Our tech experts advise
Matching the amplifier to the speakers matters more than headline watts, and the gains want setting with a meter rather than by ear. It needs a fused feed from the battery on the correct cable gauge. Installation is priced per vehicle, so get in touch with your make, model and year and we will confirm what it needs. See car audio installation.
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Our team fits car audio, stereos, dash cams and vehicle security at our workshop in Beeston, Nottingham. Tell us your vehicle and we'll confirm the parts and a fitted price.
- 1
Tell us your vehicle
Make, model and year, and what you'd like fitted.
- 2
We confirm the parts
Fascia, wiring and interfaces checked for your car, with a fitted price.
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Bring it to our Beeston workshop and we do the rest.
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Plug & Play Kits
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Focal Inside Series
The Focal Inside offer is aimed at all drivers wishing to replace their car's original system with a hi-fi quality Plug & Play solution that integrates easily, without modifying the interior. Different configurations are available by brand (over 50 brands), by car model (1000 vehicle models).
Focal Car Audio
Deliver exceptional sound clarity and precision for your vehicle.
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Frequently Asked Questions
Q: How do I choose the right amplifier for my speakers or subwoofer?
A: Match the amplifier's RMS output per channel to the RMS handling of your speakers or subwoofer at the same impedance. The Specification tab lists the power figures. If in doubt, contact CEN with your setup and we will recommend a match.
Q: What wiring do I need to install this amplifier?
A: You will need an amplifier wiring kit sized to the amplifier's power draw, typically including power and earth cable, a fuse, RCA leads and a remote wire. CEN stocks complete wiring kits, and the amplifier's fuse rating is the guide to the cable gauge required.
Q: What class of amplifier is this and does it matter?
A: Class D amplifiers are compact and efficient, ideal for subwoofers and modern installs. Class AB designs are traditionally favoured for outright sound quality on mid and high frequencies. The class is listed in the Specification tab where provided.
Q: Will an amplifier work with my factory head unit?
A: Yes, in most cases. If your head unit has no RCA outputs you will need a line output converter to feed the amplifier a clean signal. CEN stocks line output converters and can advise the right one for your vehicle.
Q: Can CEN install this amplifier?
A: Yes. CEN offers professional amplifier installation from our Nottingham premises, including secure mounting, wiring and setup. Contact us to book.
Q: Can the Focal Impulse 4.320 power a subwoofer?
A: Yes. In 3-channel mode it powers a pair of speakers at 55W RMS each while sending up to 160W to a subwoofer. The rear channels have an adjustable high- or low-pass filter (40-200Hz) and a 0-180° phase control for blending the sub with the front speakers.
Q: Does the Focal Impulse 4.320 accept speaker-level inputs from a factory radio?
A: Yes. It has both preamp and speaker-level inputs, and comes with an 8-inch speaker input harness and a 7-inch RCA line input harness, so it can connect to an aftermarket receiver or a factory radio.
Q: Is a wiring kit included with the Focal Impulse 4.320?
A: No, the wiring kit is not included. Focal recommends 10-gauge power and ground leads with a 25A fuse, or 12-gauge leads with a 15A fuse for power wire shorter than 10 feet. The box includes the power/speaker output harness, input harnesses, two 25A ATO fuses (one installed in an in-line fuse holder), two mounting brackets and a user manual.
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