Intermediate build

A Full System Rebuild: Doors, Subwoofer and One Amplifier

Researched from published relations and manufacturer specifications. Updated 2026-09-17.

The complete parts list

Grouped by function rather than by price, so you can see what each part of the system costs on its own. Every line links to the product, and the total is computed from catalog prices rather than typed by hand.

What you can skip

Telling you not to buy something is what makes the rest of this list worth reading. On this build, these are the things people add that are not earning their place.

• A separate monoblock. The fifth channel here is a genuine 300 watt class D channel, not a token.
• Rear components. Rear fill wants coaxials: a separate rear tweeter pulls the image backwards.
• Full coverage butyl. A quarter coverage on the outer skin does most of the work and saves both money and weight.

What to upgrade first

When the budget comes back around, this is the order that gets the most for the money.

1. A DSP, once everything is in. Time alignment is where most remaining sound quality lives.
2. A dedicated monoblock and a second subwoofer, if bass is the priority rather than the front stage.
3. An aftermarket head unit, if the factory unit turns out to be the limit after the converter is in.

Frequently asked questions

Is a five channel amplifier a compromise?

Less than it used to be. The real limitation is the subwoofer channel, which on most five channel amplifiers is not stable below 2 ohms, so it cannot present the load a dedicated monoblock can. For a single dual voice coil subwoofer wired to 2 ohms that is not a compromise at all, and the halved wiring is a genuine benefit.

Do I really need to deaden the doors?

For a component front stage, it is the highest value item on this list. Sealing the inner door skin stops the speaker back wave cancelling the front wave around the edge of the cone, which is often a larger improvement in output than a more expensive speaker. Butyl on the outer skin then stops the panel ringing along with the music.

Where should the tweeters go?

As high and as far forward as the car allows, usually the sail panel or the A pillar, aimed roughly at the opposite headrest. Imaging comes almost entirely from tweeter placement, because the woofers are down at ankle height and the ear cannot localise low frequency well. Crossing over too low for the mounting location is the usual mistake.

How much power do the door speakers actually need?

Far less than people expect. Most 6.5 inch component sets are rated somewhere between 50 and 100 watts RMS, and the four channels on this amplifier comfortably cover that. Sensitivity matters more than power in a door: three decibels of sensitivity is worth the same as doubling the wattage, and it is usually free in the choice between two sets.