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What Is a Mono Car Amplifier? How do I Wire Monoblock?

Having an amplifier installed in the car audio systems puts the listening experience on a higher level.

When looking at the amplifier, you may come across different classes, sizes, styles, working with different impedances, having a different number of channels, or even those with a single channel, known as monoblocks.

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But what is the monoblock car amplifier, and how does it work? Let’s find out below:

A monoblock amplifier is a single unit responsible for amplifying a single mono-channel. Monoblocks are typically larger, heavier, and more expensive than multi-channel amplifiers, but they can deliver louder sound with less distortion because there’s no sharing of components between channels like in multi-channel amplifiers.

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Tip: If you have more than one subwoofer, you should use a separate monoblock amplifier for each driver or one multi-channel amplifier.

Using a multi-channel amplifier can make the installation easier with less wiring, but multi-channel amplifiers cannot power the strongest subwoofers.

Also, multi-channel amplifiers do not produce frequencies around 20 or 25Hz needed by the big subs, so if you have two subs with 2,000W RMS each, you have to use two monoblocks, for example, Skar Audio SKv2-2500.1D (link to Amazon).

In the article below, I will explain more about monoblock amps and will only refer to subwoofers as they are the most common application for monoblock amplifiers.

However, keep in mind that you can use a monoblock amplifier to power any car speakers, including your tweets and mid-range speakers.

The downside is that those systems are costly and rarely installed in cars.

Are Monoblock Amplifiers Better Than Multi-Channel Amplifiers?

The main benefit of using two monoblock amplifiers in your car for two separate channels instead of one two-channel amplifier is signal and energy isolation.

When you use two monoblocks, you use separated transformers and a power supply to each channel, and this separation significantly improves sound quality.

In other words, you dedicate the total energy of the amplifier to the single channel, and the effect is fantastic.

It does not mean that stereo amplifiers are bad. They are great and used in the majority of cars. However, mono amplifiers for vehicles are often used to produce deep, strong bass, and they can do it very well.

The total power produced by monoblock goes towards one single speaker without any signal distortion.

Monoblocks usually work in 4, 2, or even 1 Ohm minimum impedance, which strengthens the mono signal even more. When you have a subwoofer in your car, having a separate monoblock subwoofer amp is the right way to go, especially if it is made in high performance class d technology.

More about class D amplifiers you can find in this article explaining if class D amplifiers are good for car audio.

how to wire car mono amplifier

The disadvantage of using a monoblock is its size and weight. Usually, they are much bigger than stereo amplifiers, so when you want to install one in a small trunk, it may be challenging.

Also, when you need to use monoblocks to power speakers, you need to have at least two of them if you’re thinking just about door speakers. Or, even more, when your project is more ambitious, you will want to have a dedicated amplifier for each speaker in a car.

Another reason why monoblocks are not so popular in typical car stereo systems is their price. Monoblocks are over twice as expensive as two-channel amps, but with price comes unquestionable quality. If your budget allows you and you have room in a car, not many other things in the system will be as powerful as a mono block amplifier.

What Is the Purpose of a Monoblock Amplifier?

Monoblock can be used to power either a subwoofer or speakers, but for speakers, it has to be one amplifier per channel or even one amplifier per single speaker.

When you decide to build a system this way, the sound effect will be astonishing. Just imagine each door speaker with a dedicated amplifier. Can anything be better?

However, this solution is quite expensive for most cars and most often considered by audiophiles that pay attention to how things sound and value perfect tones more than anything else.

But, if monoblock amplifiers can power audio at home, why do no install it in a car?

Before 2000, one of my friends had installed three small chrome Genesis MK1 amplifiers in his BMW Z4. Two for door speakers and one for a subwoofer. I do not remember how powerful they were, but looking today at the manuals, it must have been at least 100W RMS per channel.

Listening to music in this car was something I will never forget for the rest of my life, such unbelievable power, acoustic, every sound clear. 

car mono amplifier Genesis MK1
Genesis MK1 monoblock

You have to try this, and if you are not thinking about installing monoblocks for stereo in the car, try to find an acoustic studio and ask for a demonstration.

First, listen to the same speakers with a stereo amplifier, and then with hi-end separated monoblocks. You will not regret it.

How Do I Wire Monoblock in a Car?

When you want to connect a mono amplifier to the subwoofer, the process is the same as for multichannel amps, and it should not take you more than half an hour if you follow the short guide below.

  • Disconnect the negative battery terminal. Do not play with car electricity or audio system with the battery grounded.
  • Run the power wire from the battery through the firewall to the amplifier. You can also do it from the cabin towards the engine. It is up to you which way you will find it more comfortable or with better access to the wall.
  • Cut the power cable and place a fuse holder close to the battery. You should place the main fuse under the hood for safety reasons.
  • Run a ground wire from the battery to the amplifier. Although many people use for ground any chassis connection in the trunk area, you may increase resistance by doing so and in effect, lose some power from your amplifier. In the case of the subwoofer, I would not risk any power loss. Use ground wire with the same gauge as a power wire. Both are equally important when it comes to power.
  • Run a signal wire from the head unit to the amplifier. Place RCA cables on the other side of the car than the power wire. Otherwise, when you keep them together, you may hear engine noise in the speakers, and this is the last thing you want to hear after installing a brand new amplifier.
  • Connect a remote if your mono amp comes equipped with it. You can run remote wires together with signal wires. That will allow you to adjust the amplifier’s volume from the driver’s seat without opening the trunk every time you need to change the bass.
  • Connect remote wire and signal wires with the amplifier.
  • Connect an amplifier with power and ground wires. Make sure to use wire gauges matching amplifier portals.
  • Place your monoblock in its position and bolt it down. Ensure the amplifier is installed in place with enough free air around, especially when it is A or AB class because they tend to create a lot of heat. When installing a powerful amplifier, you may need to place it vertically instead of on the floor in a trunk for better ventilation. Also, bolt it down securely, so it will not move in the trunk every time you brake or turn.
  • Connect speaker wires from the amp to the subwoofer . Try to make this connection as short as possible. It is better to create a more extended power connection and even screw an amplifier to the enclosure than use 4 feet long speaker wires.
  • When you have all connected and secured, re-connect the battery with your car chassis. Connect back battery to the primary ground wire.
  • Turn on the engine and test an amplifier. Do not start with full volume; increase it gradually. Set up your amp and make necessary adjustments to the high and low pass filters. Also, when you are using a crossover, now it is time to test all possible settings and find bass you will like.

Why Do Monoblock Amps Have More Than One Terminal?

Monoblock has only one channel, and what you see is the dual output for this one channel. Dual outputs in mono amplifiers do not have an option known from multichannel amps “bridge” and are often used to connect multiple subwoofers. Those are known as dual-mono amplifiers.

mono car amplifier with 2 channels
Mono car amplifier with dual speaker outputs

Many monoblock car amplifiers have four or more speaker terminals. Although they look like either two positive and two negative or two left and two right, in reality, this one audio channel.

Another way to use dual speaker terminals is for very powerful subwoofers, where you need to use low gauge wires that will not fit into a single terminal. Run a double wire from two positive terminals and place them in the same speaker’s output and the same for the negative.

Again, this is a handy feature also if you want to connect two woofers in parallel to “separate amplifier channels”.

Or, when you do not use both pairs of terminals, make a connection from one and leave the other terminal empty. This is one channel amplifier, so you will not lose any signal.

How to Match The Monoblock Amplifier With a Subwoofer?

Whether your mono car amplifier has a single or dual output, you have several ways to connect it with your subwoofers. Below are the most popular wiring alternatives with one or two speakers.

All monoblock amp wiring diagrams are from Rockford Fosgate (link opens in the new window). In this overview, you can find the most if not all possible monoblock with woofer connections:

  • When you want to power a one, single-coil woofer, impedance for both a speaker and amplifier should match.

Wiring diagram of single-coil 2-ohm subwoofer with 2-ohm amplifier:

2ohm single coil subwoofer with mono amplifier

Wiring diagram of single-coil 4-ohm subwoofer with 4-ohm amplifier:

single coil 4 ohm woofer with monoblock

Wiring diagram of single-coil 8-ohm subwoofer with 8-ohm amplifier:

8 ohm single coil with mono amplifier
  • For using a single speaker but with dual voice coil, you have options to connect them either in parallel or in series, depending on the amplifier and subwoofer’s impedance:

Wiring diagram of dual voice coil 2-ohm subwoofer with 1-ohm amplifier:

dual voice coil with mono amplifier

Wiring diagram of dual voice coil 4-ohm subwoofer with 2-ohm amplifier:

4 ohm dual coil with mono amp

Wiring diagram of dual voice coil 4-ohm subwoofer with 8-ohm amplifier:

dual coil speaker in serie with mono amplifier
  • You will have the most connection alternatives if you use two or more subwoofers powered by one mono amplifier, and for these connections, dual outputs will be useful.

Wiring diagram of two 2 ohm single voice coil speakers and a 1-ohm amplifier:

2 woofers in parallel with monoblock in car

Wiring diagram of two 2 ohm single voice coil speakers and 2-ohm amplifier:

two 4 ohm single coil speakers with mono amp in parallel

Wiring diagram of two 4 ohm single voice coil speakers and 8 ohm amplifier:

two 4 ohm subwoofers with mono amp in series

Wiring diagram of two 2 ohm double coil speakers and 2 ohm amplifier:

two dual voice coil speakers and 2 ohm mono amp

Wiring diagram of two 2 ohm dual coil speakers and a 2-ohm amplifier:

two 4 ohm woofers in parallel with mono amp

Wiring diagram of two 4 ohm dual coil speakers and a 1-ohm amplifier

parallel two 4 ohm dual coil speakers with mono amplifier

Wiring diagram of two 2 ohm dual coil woofers and an 8-ohm amplifier

two 2 ohm speakers in serie with 8 ohm monoblock amplifier