DIY soundbar from car speakers: from theory to practice

Do you dream of powerful sound in your living room, but are not ready to spend 20-30 thousand on a branded soundbar? Car speakers are a great alternative! They are cheaper than home speaker systems, designed for high loads and often surpass the quality of budget multimedia speakers. In this article we will look at how to assemble a soundbar from car speakers with your own hands - from selecting components to final sound settings.

The main advantage of this solution is configuration flexibility. You can choose speakers with the desired impedance, power and frequency range, and experiment with enclosures (from a simple wooden box to an acoustically optimized design). But there are also pitfalls: incorrect matching with the amplifier, errors in calculating the volume of the housing, or ignoring the phasing of the speakers can nullify all efforts. We'll tell you how to avoid them.

This instruction is suitable for both beginners and those who have already dealt with car audio. We won't go into complex crossover circuits (although we will mention them), but will focus on practical solution with a minimum budget and maximum results. Ready to get started? Then let's get started!

Why car speakers are suitable for a soundbar

At first glance, car speakers are designed to work in the confined space of a car, where acoustic conditions are far from ideal. However, their design features make them universal:

• 🔊 Wide frequency range: Modern coaxial speakers (e.g. Pioneer TS-A1670F or Alpine S-S65C) cover the range from 60 Hz to 22 kHz, which is sufficient for reproducing speech, music and film effects.
• 🛡️ Increased reliability: Car speakers are designed to withstand vibrations, temperature changes and humidity - at home they will last longer than many budget home speakers.
• 💰 Price/quality: Mid-range speakers (e.g. JBL GTO629) are 2-3 times cheaper than home drivers with similar characteristics.
• 🔧 Ease of modification: They can be combined with subwoofers, tweeters and amplifiers without complex modifications.

Of course, they also have disadvantages. For example, Car speakers typically have an impedance of 4 ohms (not 8 ohms like home speakers), requiring a compatible amplifier. They can also sound “harder” due to the lack of acoustic design designed for the room. But these problems can be solved—we’ll talk about that later.

⚠️ Attention: Do not use speakers from old Soviet cars (for example, VAZ-2106 or GAZ-24). Their paper cones and weak magnets will not withstand the load from modern amplifiers and will quickly fail.

Which speakers to choose: parameters and recommendations

80% of the final sound of your soundbar depends on the choice of speakers. Here are the key parameters to pay attention to:

Parameter	Recommended values	Explanation
Type	Coaxial or component	Coaxial ones are easier to install (all in one case), component ones give better sound, but require separate installation of midbass and tweeters.
Size	13–16 cm (5–6.5 inches)	Optimal balance between low frequencies and compactness. 20 cm (8 in) speakers will require a large cabinet.
Impedance	4 ohm	Most car speakers are 4 ohms, but check for compatibility with your amplifier!
Power (RMS)	50–100 W	Do not confuse with peak power! RMS is the actual power that a speaker can handle over a long period of time.
Sensitivity	From 88 dB	The higher, the louder the sound for the same amplifier power.

Among the tested models:

• 🥇 Focal Access 165 CA1 — component system with excellent sound balance (ideal for music).
• 💎 Morel Maximo 6 — coaxial speakers with a silk tweeter (soft sound, without “metallic” impurities).
• 💰 Pyle PL63BL — a budget option with acceptable quality (suitable for movies and games).

If you plan to connect your soundbar to your TV, pay attention to speakers with wide dispersion angle (for example, Kicker 43DSC6504). They fill the room with sound evenly, even if the listener is not in the center.

Required tools and materials

Before assembly, prepare everything you need. Here is the minimum set:

Set of speakers (2–6 pieces depending on configuration)

Amplifier (or AV receiver supporting 4 ohms)

Case (wooden, plastic or ready-made box)

Speaker cable (cross-section no less than 2.5 mm²)

Terminals, soldering or connection connectors

Drill and wood bits (for attaching speakers)

Sealant or silicone (to seal holes)

Insulating material (sintepon, mineral wool)

Screwdrivers, wire cutters, soldering iron -->

If you are making a cabinet from scratch, use 15-18mm thick plywood or MDF. Avoid chipboard - it does not dampen vibrations well. For acoustic decoupling, the inner walls of the housing can be covered with bitumen vibration insulation (for example, StP Gold).

To connect to a TV or computer you will need:

• 🔌 Audio interface: Optical cable (TOSLINK), HDMI ARC or 3.5 mm jack (if the amplifier supports it).
• 📶 Bluetooth module (optional): For example, TPA3110 with Bluetooth 5.0 for wireless connection.

⚠️ Attention: Do not use thin “Chinese” cables to connect speakers! The resistance of such wires can reach 1–2 ohms per meter, which will distort the sound and overload the amplifier. The best option is copper stranded cable with a cross section of 4 mm² for midbass and 2.5 mm² for tweeters.

Connection diagram: how to connect speakers to an amplifier

The most common mistake newbies make is incorrect impedance matching. If you connect two 4 ohm speakers in parallel, the total resistance will drop to 2 ohms, which can burn out the amplifier. Here are the basic diagrams:

1. Serial connection:

   The speakers are connected in a “chain”: the plus of the first with the minus of the second. The overall impedance increases (for example, two 4 ohm speakers will produce 8 ohms). Suitable for amplifiers that do not drive low impedance loads.

   Amplifier (+) → Speaker 1 (+) → Speaker 1 (-) → Speaker 2 (+) → Speaker 2 (-) → Amplifier (-)

2. Parallel connection:

   All the pros come together, all the minuses come together. Impedance drops (two 4 ohm speakers = 2 ohms). Requires an amplifier that can support a low impedance load (e.g. Behringer NX3000D).

3. Series-parallel:

   A combination of the first two schemes. For example, two pairs of speakers connected in parallel and then in series with each other. Delivers 4 ohms with four 4 ohm speakers.

Optimal for a soundbar circuit with separate connection:

- Midbass (13–16 cm) - on a separate amplifier channel.

- Tweeters - through capacitors (crossover) or to the high-frequency output of the amplifier.

- Subwoofer (optional) - to the subwoofer output.

How to check the phasing of speakers?

To ensure that the speakers work in the same phase (not cancel each other out), connect them to an amplifier and apply a test signal (for example, a 100 Hz bass note). Place your finger near the center of the diffuser - it should move outward simultaneously on all speakers. If one is “retracted”, change the polarity of its connection.

Housing Assembly: Acoustic Design and Mistakes

The enclosure is more than just a “speaker box.” Its volume, shape and material directly affect the sound. Here are the key rules:

• 📦 Case volume must match the size of the speakers. For 16 cm midbass, 15–25 liters per speaker is optimal. Calculation formula:

  V = (Vas / (Qts^2 - 1)) * 0.85

  where Vas — equivalent speaker volume (indicated in the datasheet), Qts - quality factor.

• 🔨 Hardness: The walls of the housing must not vibrate. They can be strengthened using internal stiffeners or a second layer of plywood.
• 🕳️ Bass holes: If the cabinet is closed, the low frequencies will be “muffled”. Solution - bass reflex (tube of a certain diameter and length) or bandpass (for subwoofers).
• 🧹 Absorption: The inside of the housing must be filled with sound-absorbing material (sintepon, mineral wool) by 50–70%. This reduces resonance.

An example of calculating a bass reflex for a speaker Alpine S-W12D4:

- Pipe diameter: 7–10 cm.

- Length: ~20 cm (depending on the volume of the case and the frequency setting).

- Located on the front or back wall.

⚠️ Attention: Do not use plastic tool boxes or food containers as enclosures! They resonate at medium frequencies, which leads to a “booming” sound. The exception is specialized plastic housings for acoustics (for example, B-Craft).

Sound settings: from balance to equalizer

After assembly, the soundbar needs to be “trained” to suit your room. Here's the step-by-step plan:

1. Positioning:

   Place the soundbar centrally under the TV or on the wall. Tilt angle: 0–15 degrees towards the listener. Avoid placing in niches or close to corners (this will enhance the bass uncontrollably).

2. Channel balance:

   Play a monaural signal (such as a newscaster's voice) and adjust the volume of each speaker so that the sound comes directly from the center.

3. Equalizer:

   Use REW (Room EQ Wizard) or the amplifier's built-in equalizer to smooth out peaks and valleys. Typical settings for a soundbar made from car speakers:

   • 60–80 Hz: +2–3 dB (bass boost).
   • 200–500 Hz: -1–2 dB (reduced boominess).
   • 3–6 kHz: +1 dB (improves speech intelligibility).

Test tracks:

Check the sound on different materials:

• 🎵 Music: «Bohemian Rhapsody» (Queen) — checking the dynamic range.
• 🎬 Movie: rain scene from "Blade Runner 2049" — detailing of high frequencies.
• 🎮 Games: «Hellblade: Senua’s Sacrifice» - spatial sound.

If you don't have a measurement microphone, use mobile apps like AudioTool (Android) or Studio Six Digital Audio Tools (iOS). They will help you roughly estimate the frequency response (amplitude-frequency response) of your system.

💡

The most common mistake when setting up is over-boosting the bass. This leads to sound smearing and overloading the speakers. It's better to undercut the low frequencies a little than overdo it!

Common mistakes and how to avoid them

Even experienced craftsmen sometimes make mistakes. Here's what most often spoils the sound of homemade soundbars:

Error	Consequences	Solution
Impedance mismatch	Amplifier overheating, sound distortion	Use a connection diagram that matches the capabilities of the amplifier (see section 4).
Lack of sound insulation of the case	Resonance, boxy sound	Cover the walls with bitumen vibration insulation and fill the body with padding polyester.
Incorrect speaker phasing	Weak bass, empty sound	Check the movement of the diffusers (see spoiler in section 4).
Case too small	“Thin” bass, speaker overload	Increase the volume or use a closed enclosure with a subwoofer.
Cheap cables	High frequency loss, noise	Use copper cables with a cross-section of 2.5 mm² or more.

Another common problem is nonlinear distortion at high volume. They appear as "wheezing" or "rattling". Reasons:

- Exceeding the amplifier power (the RMS of the speakers is lower than that of the amplifier).

- Mechanical limitations of the speaker (for example, insufficient cone travel).

- Clipping (signal limiting) due to too high level at the amplifier input.

Solution: reduce the volume on the source (TV, computer) and increase it on the amplifier. This will reduce noise and distortion.

Additional enhancements: from Bluetooth to multi-channel audio

A basic car speaker soundbar already sounds better than many factory solutions, but it can be upgraded:

• 📱 Bluetooth module: Install the board TPA3110 with Bluetooth 5.0 for wireless connection. The cost is about 1,500 rubles.
• 🔊 Subwoofer: Add a powered subwoofer (such as Sony SA-W2500) for deep bass. Connect through the amplifier's subwoofer output.
• 🎛️ Digital processor: Devices like MiniDSP 2x4 HD allow you to more accurately adjust the sound to the room (correction of frequency response, delays, etc.).
• 🔄 Multichannel audio: If you have a 5.1 or 7.1 amplifier, you can assemble a full-fledged system: soundbar as front speakers + rear speakers + subwoofer.

For movie lovers, an interesting solution would be to add height speakers (for Dolby Atmos formats). They can be installed on the ceiling or use reflective modules (for example, Onkyo SKH-410). However, this will require a supporting AV receiver (with height channel output).

How to connect a soundbar to a TV via HDMI ARC?

1. Make sure your amplifier supports HDMI ARC (eg Yamaha RX-V4A).

2. Connect the HDMI cable from the port HDMI ARC TV to the corresponding amplifier input.

3. In the TV settings (Sound → Sound Out) select HDMI ARC or External speakers.

4. On the amplifier, activate the ARC mode (usually in the menu Audio Settings).

5. Check the sound - if there is no sound, restart both devices.

FAQ: answers to frequently asked questions

Can I use speakers from different manufacturers?

Technically yes, but this is fraught with sound imbalance. Speakers of the same brand and series usually have similar characteristics (sensitivity, impedance, frequency response). If you mix, for example, Pioneer and JBL, one may sound louder than the other, or there will be a noticeable difference in timbre.

If you still want to combine, select speakers with the same sensitivity (for example, 90 dB) and close impedance (all 4 ohms). Also be sure to adjust the volume balance on the amplifier.

Which amplifier is best for a soundbar?

Optimal options:

• Budget: Lepai LP-2020A+ (20 W/channel, suitable for small rooms).
• Middle class: Behringer A500 (500W, support 2 Ohm).
• For cinema: Yamaha RX-V385 (AV receiver with Dolby Digital).
• With Bluetooth: Fosi Audio BT20A (compact, 100 W/channel).

The main thing is that the amplifier supports the impedance of your speakers (usually 4 ohms) and has sufficient power reserve (the RMS of the amplifier should be 20-30% higher than the total power of the speakers).

Is it necessary to make a crossover for tweeters?

If you have coaxial speakers (where the tweeter is built into the midbass), a crossover is not needed - it is already inside. For component systems crossover is required, otherwise the tweeters will burn out from low frequencies.

You can buy a ready-made passive crossover (for example, Soundstream VX-65) or solder it yourself. Typical circuit for a 2-way crossover:

• 4.7 uF capacitor + 0.47 mH coil for tweeter (cut off at 4 kHz).
• 1.5 mH coil for midbass (cut at 200 Hz).

How to reduce noise and background in a soundbar?

The noise usually appears due to:

1. Poor grounding: Connect the amplifier and signal source to the same outlet through a surge protector.
2. Cheap cables: Replace them with shielded ones (for example, Canare 4S11).
3. Interference from mobile phones: Keep your smartphone 1 m away from the amplifier.
4. Bad power supply: If the amplifier is on a chip (for example, TPA3110), use a power source with a current of at least 5A.

Also check input signal level - if it is too low, the amplifier will “raise” the noise along with the useful signal.

Is it possible to make a soundbar without an amplifier?

Technically yes, but the sound will be quiet and distorted. The speakers have low sensitivity (usually 88–92 dB) and require an amplifier for normal volume. Alternatives:

• Use active speakers (with a built-in amplifier), but this is no longer a budget option.
• Connect speakers to headphone output TV or computer (maximum 1–2 W, enough for a test, but not for constant use).
• Build an amplifier on a chip LM386 (power 0.5–1 W, suitable for a small room).

An amplifier is required for full sound. Even the simplest Lepai LP-2020A+ costs only 2–3 thousand rubles and will provide 20 W of pure power per channel.