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Focal FD 4.350

Compact 4-channel amplifier — 58 watts RMS x 4

Item #: 091FD4350

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When size matters

If you want an audio upgrade but you're short on room, Focal's FD 4.350 may be the amp for you. This 4-channel amplifier packs a respectable punch, driving four speakers with up to 100 watts RMS each even though it's only the size of a small paperback book. Explore your options with 2- and 3-channel mode to power subs and speakers in different combos.

No sacrifices

The amplifier's active high- and low-pass crossovers let you get hands-on with sound optimization as well. And if you're keeping your factory radio, the amp comes with external audio transformers that automatically detect and convert the high-level signals from your speaker wires.

Cool under pressure

The FD 4.350 uses Direct FET Technology to dissipate heat efficiently from its aluminum chassis, ensuring long-term reliability. And speaking of saving space, you can stack this amp with others in the FD Series to power an entire system.

Without cover


  • ultra-compact D class 4-channel amplifier
  • 58 watts RMS x 4 at 4 ohms (100 watts RMS x 4 at 2 ohms)
  • 200 watts RMS x 2 at 4 ohms (bridged mode)
  • CEA-2006 compliant
  • stackable aluminum chassis
  • Direct FET® Technology for efficient heat dissipation
  • cable accessories included
  • high-level inputs with auto-detection (2 external transformers) and RCA low-level inputs
  • high- and low-pass crossover: adjustable 40-400 Hz
  • 10-gauge power and ground leads recommended — wiring and hardware not included with amplifier
  • fuse rating: 30A x 1
  • dimensions: 7-7/8"W x 1-11/16"H x 4-5/16"D
  • warranty: 1 year
  • Our 60-day money-back guarantee

My system has plenty of power. Who needs an amp?

You might think you don't need an amp because you have a 400-watt system in your car, or because your new stereo puts out 50 watts a channel. But those are peak wattage ratings, which may boil down to 15 or 20 watts per channel, using the more realistic RMS rating. An amp sends your speakers the power they need to deliver your music with clarity and impact, whether you're using factory speakers or high-performance components. And low-frequency reproduction requires lots of power, so an amp is an absolute must if you're adding a sub to your system.

Focal FD 4.350 Reviews

Average Customer Review:

3 Reviews

Focal FD 4.350

Written by: Carl from Nashville on February 12, 2016

Just as advertised

Pros: Nice small unit with good sound

Cons: None

Amazing quality in a small size

Written by: bigaudiofanatic from New Jersey on December 14, 2015

These amps are small, powerful and amazing. One thing the other review did not mention is that you do not turn the gain all the way up. You use this to tune your amp so there is no clipping in your signal. Proper tuning of the gain for your system insures long life of your speakers. no issues with these at all.

Pros: Small, simple.

Cons: Terminals could be a little bigger.

Poor quality amp

Written by: Milton from California on June 18, 2015

Crutchfield Customer Review (What's this?)

Poor quality amp! All the harnesses was cheap made...include the fuse holder. When you crank it up the bass was popping! & that only less than 1/2 way! First I though was my speaker? Than I exchange with another amp (Rockford T400x4ad) speaker did not pop! Even I crank it up full! I love all my Focal speaker! But this is junk!

Pros: Small size, fit all most any where!

Cons: All harnesses are cheap made!

Hands-on research

What's in the box?

Download owner's manual

  • 4-channel amplifier
  • Two 30-amp AGC fuses (1 installed/ 1 spare)
  • 2 Terminal covers (installed)
  • 8" Power wire with in-line fuse holder
  • 2 External speaker level input transformers
  • Two 8" Speaker input harnesses (Molex plug on one end and tinned bare wire on the other)
  • 8" Speaker level input transformer harness (Molex plugs on both ends)
  • Four 2" Self-tapping screws
  • 2.5mm Allen wrench
  • 9 Crimp-on spade connectors (14/16 gauge)
  • 2 Crimp-on spade connectors (10/12 gauge)
  • 6 Red spade insulators
  • 5 Black spade insulators
  • User manual (English/ French)

Product Research



CEA-2006 Compliant: CEA-2006 is a system of testing and measurement for mobile audio amplifiers. This voluntary standard advocates a uniform method for measuring an amplifier's RMS power output. The criteria for measuring power uses a DC input voltage of 14.4 volts and the RMS power output is measured into a 4Ω load, with 1% or less Total Harmonic Distortion plus noise (THD+N), and over a frequency range of 20 Hz to 20 kHz (for full range amplifiers). CEA-2006 standards allow consumers to compare car amplifiers and receivers under the same conditions (apples to apples). Using CEA-2006 criteria, the Focal FD 4.350 is rated at 58 watts RMS x 4 channels.

2Ω Stable: The amplifier can also support a 2Ω load; the 2Ω power output is 100 watts RMS x 4 channels.

4-Channel Amp: The FD 4.350 is a 4-channel amplifier, basically two 2-channel amps in one chassis. The inputs, outputs, and controls are labeled CH 1-2 or CH 3-4.

Bridgeable: Both sides of the amp are independently bridgeable; it can be used in 4-channel, 3-channel, or 2-channel modes. The bridged power output is 200 watts RMS x 2 channels into 4Ω.

Stackable: All the FD series amps (FD 1.350, FD 2.350, and FD 4.350) have the same footprint, and can be stacked on top of one another.

Speaker Level Input: Two external speaker level input transformers are included, used when your source unit doesn't have RCA outputs. The transformers are connected to the amp with the included wiring harness. The transformers' dimensions are approximately:

  • Width: 2-3/8"
  • Height: 1-1/4"
  • Depth: 2" (3" including wiring)

Auto Turn-on: When using a speaker level input, the amp will turn on automatically when it senses the input signal.


Input Select: The input select switch has three options:

  • 1/2: the stereo signal at the CH 1-2 input is shorted to the CH 3-4 input, so both sets receive a stereo input
  • 3/4: channels 1-2 and 3-4 maintain discrete inputs
  • 1+2: channels 1-2 receive a stereo signal; that signal is then summed and sent to channels 3-4 as a mono signal

Independent Controls: The Channels 1-2 and 3-4 have separate controls for gain, crossover mode, and crossover point frequency:

  • Gain: rotary control; continuously variable from 200mV to 5 volts line level (RCA) and from 400mV to 10 volts speaker level
  • Crossover Mode: three position switch; LPF (Low Pass Filter), Full (full range), or HPF (High Pass Filter)
  • Frequency: rotary control; continuously variable from 40 Hz to 400 Hz


Power Connections: The power and ground connections are 0.3" wide screw terminals. A Phillips-head or flat blade screw driver (not supplied) is required to tighten/loosen the terminals. Crimp-on spade connectors are included for both terminals.

Speaker Outputs: There are 0.22" wide screw terminals for four speakers and the remote turn-on lead. A Phillips-head or flat blade screw driver (not supplied) is required to tighten/loosen the terminals. Crimp-on spade connectors are included for all the terminals.

Line Level Input: The line input is two pair of stereo RCA jacks.

Speaker Level Input: Two external speaker level input transformers and wiring harnesses are included for the speaker level input. (Each has inputs for two speakers.)

Our Product Research Team

At Crutchfield, you'll get detailed, accurate information that's hard to find elsewhere. That's because we have our own in-house Product Research team. They verify what’s in the box, check the owner's manual, and record dimensions, features and specs. We stay on top of new products and technologies to help people make informed choices.

Product reviews from the Crutchfield Labs

Great compact amp!

Written by Chance, Advisor, on 7/22/2015 2:47:00 PM
I installed this in my Honda Accord under the passenger seat. I was hoping to find something compact, yet clean sounding, and this amp is perfect. I have it powering Focal components up front and a pair of coaxial speakers in the rear. My sound is crisp and clean at all volume levels and the amp is tiny and fits well! I even had enough space to put a JL Audio amp under the same seat to power a subwoofer.
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