How to Upgrade a Weak Sound System in a New Car

Upgrading your Car’s Audio System nowadays appears to be scary than it truly is. This general guide will help you get the sound you were looking for, that you and the family can both enjoy at the end of this article. You will be able to find out where to buy all of this we are talking about.

What’s wrong with the sound?

First, identify what your sound is missing, is it more bass? Does your door speakers sound weird? Do you want louder?

OK, lets first start on what, year make and model you have. Depending on the manufacture, you will have one or all of the following sizes. 1″, 2.5″ 3.5″, 4″, 5.25″, 6″, 6.5″, 7″, 8″, 6×9″ speakers and or subwoofers. Most American Car’s share 6.5″, 3.5″, and 6×9 combinations. Most European cars, share 6.5″ in the doors, sometimes 2, and 3-way speakers. A simple google search, in most cases, will help you find the speaker you are looking for be sure to use, “year, make, model, trim level speaker size.”

Replace that is there! So if its a 6.5 co axle, choose that. If its a component setup, which means a tweeter with a crossover based on its size, replace that.

From there, you will get a general listing on what that sizes the doors, dash, and rear deck.

Example: “2020 VW PASSAT GT Speaker sizes.”

Results display, 6.5″ components up front and 6.5 in the rear.

Note, the speakers mounting cutout and depth as not all the times the speaker will drop in without a spacer.


Now, let us identify what your wanting, that is, louder? If you are, you’re going to need either upgrade the radio and add an amplifier or integrate with a DSP or line out convertor box.

We recommend since this is a new car article to integrate with a DSP or lineout convertor. Retaining your factory radio is everything, in our opinion. Companies like Metra and PAC are a little slow to develop aftermarket radio integration, like a wiring harness, antenna adapter, and dash kit. Please note most New Fiat Chrysler Products late 2018 and up with a big screen up front require additional parts like resistors and diodes at + a lineout convertor and or DSP. This also goes for BMW and Mercedes, as they know to have the moST system. This Data Canbus infotainment system controls the Car’s audio, air conditioning, lighting, and more.

What is a lineout convertor? This helps you integrate a factory signal off the amp and speaker wires; typically, a rotational knob allows you to boost the signal from the converter box.


What is DSP? This is a Digital Sound Processor that allows you to integrate into the factory system, and tune with a piece of software from your phone or laptop with a graphic representation. This does require a skill level or intermediate.

Power Ratings and matching speakers with amplifiers

Once you have that sorted out, picking your speaker, you’ll need to pair the correct speakers to an amplifier. We suggest pairing via RMS ratings and budget.

Please pay attention to the ohm load of the speakers, aka the impedance of the speakers as they play a big roll in the power output of amplifiers.

Impedance is usually single 4 ohms. Sometimes you can find them in 2 ohms and 8 ohms.

There is no such thing as peak power ratings; this is a marketing stunt from mainstream companies.

Try to match the RMS power rating on the amplifier.

What is RMS? Root Mean Squared, which means power output almost all the time.


Let’s say your stock system is 35 watts per speaker. You’re going to upgrade to possibly a 75 RMS speaker. The 75-watt speakers would need a 75 watt RMS per channel amplifier, this based on the Car, would, in return, give you a louder system vs. the sound you had at 35 watts per speaker per channel you had initially.


Now we have to pick an amplifier; most amplifiers come in 1 or for five channels.

1 Channel is usually a monoblock amplifier or full range

2 Channel is often high pass or low pass filtered channels

4 Channel is often high pass and occasionally controllable per channel

5 Channel is four high pass channels and one mono channel, seen as an and-one mono channel.

What is a high pass? Tweeters and midrange frequencies, aka the depth of the voice.

What is the low pass? Typically this is the bass you hear.

What is monoblock? This is usually a one channel bass amplifier technology.

What is the full range? This feature allows the amplifier to play the full range of frequencies of the amp, which means Bass, Mids, and Highs.

Not all amplifiers are made equal! Usually, if it is good to good to be true, it probably is. But dont worry! We have at the end of this guide a place that is perhaps the best place to buy car audio!

Wire, RCA, Batteries, and Power, and Distribution

When you get into power and wires, this is very straight forward. Understand to make power; you need to have reserve power. Running Multiple amplifiers means you need more power wire from the battery and to your amplifier distribution block. The same goes for all your cables, and typically with your RCA cabling, it’s one run per channel.

We recommend using top quality RCA cables.

Not all cabling is created equal, and your going to wanna grab the Oxigen FREE Copper, also know as OFC wired or Tinned coated OFC wire. There is a CCA wire, which is copper-clad aluminum. Please stay away from this wire, corrodes, melts, and you’re probably going to have to keep on replacing it.

Long Story Short, it’s tinned OFC for the win!

Once that is handled, you’re going to wanna distribute all this wire. Your going to wanna get the ones that fit the wire your running. We would recommend using SMD products, also known as Steve Meade Design Products. These are made in the USA and tested on safety and quality.

Here are some additional optional recommendations with power wire:

Use wire ferrules and heat shrink. These will protect wire ends from accidental wire fraying.

Choosing Subwoofers

It is time to figure out what the bass drop you’re looking for; subwoofers are sized in the range from 6.5″, 8″ 10″, 12″, 15″, 18″, 21″ and 32″ single voice coil and dual voice coil configurations.

Smaller subwoofers, tighter area to work with, bigger subwoofers typically want a lower hertz or bass drop.

You can’t ever go wrong with a single 12 or dual 12 set up!

Grabbing 2 – dual voice coil 4-ohm subwoofers wiring them down to 1 ohm with + to + and – to – will get you to a safe 1-ohm load on your bass amp you have chosen.

If you chose a dual voice coil 12 from + to + and – to – will bring you down to a 1-ohm load.

Keep an eye on air space; you’re going to need to make sure you can fit the subwoofer box based on that info leading into the box section.

Choosing a Box

Here you are ready for everything now you need a sub box.

Tune the FS of the sub to the output of the box. Try to stay away from prefabs on Amazon and eBay. They have air leaks and, overall, a horrible experience. Getting one from our provided sources below is all your going to need, as seen below!

Final thoughts and sources

Finally, we have summed up what it takes to get an upgraded sound on that new Car.

Down4SoundShop is the #1 Place Car Audio Online.