ST400 Classic Motorcycle Amplifier


Kenwood's super-compact KAC-M1814 will add new clarity and impact to the basic sound system of almost any kind of vehicle on land or water, and it'll fit in a lot of places when space is tight. This marine-rated 4-channel amp will pump up your audio system with 45 watts RMS per channel — that's more than twice the power of most motorcycle stereos or marine receivers. The amp uses plastic covers to protect its connections and features a conformal-coated circuit board that keeps out moisture and salt, so the tunes won't stop just because of a little wetness.

When you use the speaker-level inputs, the amplifier will sense the signal and turn itself on, so you won't need to run a separate remote turn-on lead to the receiver or fuse box. Kenwood goes to great lengths to ensure good sound quality, putting the preamp and output power amp stages on separate circuit boards for better, cleaner performance.

The Kenwood KAC-M1814 4-channel amplifier is effectively two full range 2-channel amps built into one chassis, labeled A (front) and B (rear). Each section of the amp is bridgeable, so it can be wired as 4-channel, 3-channel, or 2-channel. The amp features a conformal coating on the circuit board to protect it from moisture. This allows you to use the amp for marine applications or on All-Terrain Vehicles (ATVs).


RMS Power Output (Watts x Channels) 45 x 4
Peak Power Output (Watts x Channels) 100 x 4
Power at 2 Ohms (Watts x Channels) 45 x 4
Bridged Power (Watts x Channels) 90 x 2
Minimum Impedance Bridged 4
Minimum Impedance Unbridged 2
Best Frequency Response 20-20k Hz
THD at Rated RMS Power 1%
Signal to Noise Ratio 82 dB
Input Voltage 14.4v
Amplifier Class D
Low-Pass Crossover Frequency 50-200 Hz
Low-Pass Slope (dB/octave) 12 dB/octave
High-Pass Crossover Frequency 50-200 Hz
High-Pass Slope (dB/octave) 12 dB/octave
Fuse Rating 15
Speaker Level Inputs Yes
Width (inches) 8-5/8
Height (inches) 1-13/16
Depth (inches) 3-15/16


Ask a Question
  • Is there a mounting bracket for the ST400 amplifier?

    Yes, we offer a mounting bracket for this amplifier under our Installation Extras

  • Does it come with plug and play wiring

    There is a harness that plugs directly in to the motorcycle amplifier.  The other end are loose wires to connect directly to your battery and motorcycle speakers.

  • How many channels does it have? can I play with sound balance between front and rear speaker? is It water proof?

    The ST400 Amplifier has 4 channels, with front and rear output.  It is water resistant, with conforming coating to protect components from elements.

  • Will it play the music from my phone if connected with USB? Pandora?

    This amplifier will play the music from your phone, including Pandora, using the headphone jack.  You connect the plug to the headphone jack of your phone and the other end plugs in to the amp.  The USB port is for charging only.  You can also add one of our Bluetooth controllers for a wireless connection from your phone.