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Alpine PSU-300ACD

Powered System Upgrade for select 2018-up Honda Accord 4-door without factory premium sound

Item # 500PSU3ACD

The top two complaints about the way a car's factory system sounds are that there's not enough volume and...

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The top two complaints about the way a car's factory system sounds are that there's not enough volume and...

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Item # 500PSU3ACD

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About the Alpine PSU-300ACD

Fix your factory sound

The top two complaints about the way a car's factory system sounds are that there's not enough volume and there's not enough bass. Alpine's PSU-300ACD Powered System Upgrade solves both of these issues in your Honda Accord with a neat and clever combination of products designed to bring joy to all music lovers.

Fix your factory sound

The top two complaints about the way a car's factory system sounds are that there's not enough volume and there's not enough bass. Alpine's PSU-300ACD Powered System Upgrade solves both of these issues in your Honda Accord with a neat and clever combination of products designed to bring joy to all music lovers.

The components

The package includes a compact 4-channel amplifier and a powered subwoofer, both mounted in an Accord-specific bracket which you install under the passenger seat and wire up using Honda-specific harnesses. The PSU-300ACD upgrade is compatible with the factory Honda base radio and almost all other aftermarket receivers. Alpine says you should be able to install this upgrade in your car in two hours or less.

Universal power pack

Alpine's KTP-445U Power Pack amplifier increases your radio's power output to 45 watts RMS by 4 channels, considerably more than what's put out by the Honda radio. A universal plug lets you feed a signal via RCA outputs or speaker-level wiring. A built-in high-pass filter optimizes the sound for your speakers.

Compact powered subwoofer

Alpine's PWE-S8 powered sub uses a Class D amplifier rated at 120 watts RMS to drive the 8" shallow-mount, high-excursion subwoofer, so there's plenty of power for your bass. The amp features controls for phase, gain, and a low-pass crossover, so you'll be able to blend the bass with the rest of your system.  A wired remote control lets you adjust the bass level from the driver's seat. 

Important Note: This upgrade package won't work with Accords with the factory premium amplified system or with the EX-L or Touring models.


Product highlights:

  • factory audio system upgrade
  • fits select 2018-up Honda Accord 4-door without factory premium sound
  • Alpine KTP-445U Power Pack 4-channel amplifier
    • 45 watts RMS x 4 at 2 or 4 ohms
  • Alpine PWE-S8 compact powered subwoofer
    • 8" woofer
    • 120 watts RMS amplifier
  • vehicle-specific bracket holds sub and amp under front passenger seat
  • vehicle-specific wiring pre-cut and terminated
  • warranty: 1 year
  • Our 60-day money-back guarantee
  • MFR # PSU-300ACD

What's in the box:

  • PWE-S8 Powered sub and attached KTP-445U 4-ch amplifier w/ integrated brackets
  • 7' Main harness
  • 12' Loomed power cable (inline 20A fuse)
  • 9" T-harness
  • Four 10" speaker-RCA harnesses
  • Remote bass knob w/ 16' cord
  • 2.5" Strip of hook-and-loop fastener
  • Ten 6" wire-ties
  • One 1/2" self-tapping pan-head screw
  • 1 Star-washer
  • Installation guide
  • Warranty sheet
  • Alpine Technical Support contact sheet

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Not bad at all

Nathan from Gurnee on 7/8/2019

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Sounds good, way better than stock. Took a few hours to install, I'm happy so far. Adding speakers, will see if that helps as well. I'm not looking to have my neighbors hear me, just wanted to fill the empty sound of the accord sport.



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Not bad

Justin from Dallas, TX on 1/30/2019

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Verified employee purchase (What's this?)

Not super impressed. Understand it's a compact unit. Bass only seems really present with knob on max and +3 on head unit equalizer. Had it installed along with front and rear alpine components. Sounds a lot better than before... but before was pretty bad.



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Alpine PSU-300ACD

Dustin from Henderson, NV on 1/3/2019

2018 Honda Accord Sport

Verified customer (What's this?)
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Since the OEM Accord system is so terrible from the factory, this set-up sounds definitely better, that's for sure. It's louder, cleaner, and distortion free for the most part. I have a problem with the bass though. The lower notes just don't seem to hit. I'm certain it's installed correctly and all of the switches are set correctly. Alpine's instructions have you completely defeat the high pass crossovers on the 4-channel amp; a huge mistake in my opinion. The midbass was way too overpowering and muddy. I have mine set to 80hz right now and while it sounds better, something just doesn't seem right. The included instructions could use some work too. No mention of the shift console for the 2.0T. Inaccurate description of passenger seat connectors, and also steps that were left out which I felt are mandatory to access the connectors on the factory head unit. The way they have you route the power wire is not smart. I feel like it could be ran into the passenger compartment from the driver's side, which appears to be much easier. Running it through the passenger side can lead to issues with over-flexing/bending the soft aluminum A/C line, which might break. Be careful in this area.

Pros: Plug and Play No wire cutting


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13 of 14 found this helpful

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More details on the Alpine PSU-300ACD

Pat M.

Product Research


Overview: Alpine's PSU-3ACD is a dedicated 300 watt sound system designed specifically for 2018 - Up Honda Accord 4-door LX, Hybrid, Sport, and EX models (excludes Touring and EX-L models) not equipped with a factory premium amplified sound system. The system includes a KTP-445U 4 x 45 watt amplifier, a PWE-S8 8" powered subwoofer, and all the wiring needed, pre-loomed and ready to install. The PSU-3ACD also includes a remote bass knob for changing the bass level from the dash.

Wiring: The PSU-3ACD system can be interfaced with a factory radio (non-amplified) or an aftermarket radio. The included T-harness interfaces the factory wiring in the dash, providing either a speaker-level signal from a factory radio or an RCA line-level signal from an aftermarket radio, to feed to the Alpine KTP-445U amplifier. The T-harness also feeds the amplified return signal back into the factory wiring and out to each of the speakers, utilizing the factory speaker wires. The provided wiring includes a 10 ga. power wire, with inline fuse holder, that gets run to the battery, providing power for both the 4-channel amp and the PWE-S8 subwoofer.

Mounting: Alpine provides pre-attached brackets that are designed specifically to mount both the KTP-445U amp and the PWE-S8 subwoofer underneath the passenger front seat. This means no usable space in the vehicle is taken up by the sound system.

KTP-445U: The Alpine KTP-445U Head Unit Power Pack is a power upgrade amplifier that allows you to add higher output and more dynamic response to your aftermarket or factory installed car stereo system (without factory amplifiers). The Power Pack employs a 45 watt x 4 channel amplifier with an unbelievably low noise floor, taking extra care to ensure a clean signal path, with no extraneous interference. The end result is a 1 Watt Signal-to-Noise Ratio of 82dB or better. Uniquely, the amplifier distortion actually decreases at higher frequencies, resulting in a clean and clear signal where your ear is most sensitive to distortion (< 0.03% THD+N @ 1W; 1% THD+N @ rated power). The Alpine KTP-445U Head Unit Power Pack provides independent controls for the Front & Rear inputs.

  • Front & Rear Gains: The Power Pack provides simple variable gain controls (speaker level: 0.5-10V, low-level: 0.2-4V) for flexibility and a wide variety of system applications.
  • Front & Rear HPF: High-Pass selectable switches for the amplifier's Front & Rear inputs allow frequency filtering for a wide variety of speakers. Choose "Full-Range" or a selectable range (60Hz, 80Hz, 120Hz) to fine-tune your crossover points (-12dB/oct.).
  • Configurable Inputs: On the bottom panel of the Power Pack there are selectable input options to accommodate Speaker-Level (0.5V-10V) or RCA (0.2V-4V) inputs.
  • 4Ch/2Ch Modes: Selectable 2-Channel & 4-Channel options give you the control to determine source inputs, and can eliminate the need for Y-adapters.

PWE-S8: The Alpine PWE-S8 is a compact self-amplified subwoofer with pre-installed brackets that allow it to fit underneath the passenger's front seat, keeping it out of sight. The PWE-S8 includes a built-in 120 watt Class D amp along with an 8" high-excursion subwoofer. It can accept either line- or speaker-level inputs and features an Auto Turn-on circuit that will activate the amp when it senses a signal on the speaker-level inputs. An included wired remote lets you easily adjust the bass level from the front seating area. The control can be mounted under a dash panel and gives you a level range from 0 to -20 dB, relative to the gain setting on the amplifier. Controls on the subwoofer include:

  • Gain: Can vary the input level from 0.2 - 4.0 volts line-level and 0.5 - 10 volts speaker-level.
  • Low Pass Filter: Rotary control that can set the filter cutoff between 50 - 150 Hz.
  • Phase: Switches between 0˚ and 180˚.
  • Power Mode: Switches between SP IN (speaker-level input) and REM (wired remote input).

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Customer Q&A

Crutchfield asked: Why did you buy this?
I bought the Alpine PSU-300ACD because the sound quality of the factory stereo in my 2018 Honda Accord sucks. [ Carl  Dec 18, 2018 ]

1 question already asked

Does this unit require disabling of the active noise reduction system?
[ Paulf3rd  Jun 26, 2019 ]
5 answers
Yes, possible feedback issues if not done
[ Robert  Jul 02, 2019 ]
Yes it does, if you do not disable the ANC you will get distortion and a humming sound. Included instructions outline how to do it. Very easy, just needs to be unplugges.
[ William  Jun 26, 2019 ]
Yes, any aftermarket system will require disabling the ANC. Otherwise you will get unwanted booming sounds. Honestly I can't tell a difference in noise since I unplugged the ANC.
[ William  Jun 26, 2019 ]
Yes. Easy to do. Included in instructions. You have to disconnect a connector behind the passenger vent.
[ Dustin  Jun 26, 2019 ]
If your car has a ANC system yes it is smart to disable it so you don't get feedback through your speakers.
[ Jason  Jun 26, 2019 ]

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