Class D amplifiers offer numerous benefits over the traditional Class A, AB and B units. They generate much less heat, are more compact, cheaper to make and have better battery life. That’s why when I began my hunt for a new amplifier this year, I avoided the rest and place my entire focus on finding the best class D units.
I started by getting 12 different amplifiers that came highly recommended by experts. I then spent a couple of days with each amplifier and went through a rigorous process of elimination, after which I shortlisted them to a top five. You can read my review of them below.
What Are Class D Amplifiers
Before we get to my top five picks, it’s important to understand a little about class D amplifiers and amplifiers in general, particularly some of the technical stuff that your eyes usually skim over when you’re reading the product information. Knowing how to read technical specs will allow you to choose a high-quality amplifier that’s compatible with your car’s stereo.
Class D Amplifiers And Efficiency
In order to properly appreciate what class D amplifiers bring to the table, we need to first look at the other classes. The main distinguishing factor between different classes of amplifiers is their circuitry, which in turn determines how much Alternating Current (AC) they can deliver to a device while consuming the least amount of Direct Current (DC) possible (i.e. efficiency). Here’s how efficiency varies between the different classes:
Class A is the oldest and simplest type of amplifier. Class A amplifiers are always conducting electricity meaning that they can heat up with prolonged use. It also means that they’re the least efficient, with less than 30% of the total Alternating Current present being outputted.
Compared to Class A, Class B amplifiers only conduct electricity around half the time. As a result, it is actually they are much more power-efficient (70%) than Class A units.
Class AB circuits combine elements from Class A and Class B circuits. Most notably they contain biasing diodes in their Class B chain, which helps to reduce the characteristic distortion from that type of circuit. Class AB circuitry combines the power efficiency (70%) of Class B with the signal purity of Class A.
Thanks to some clever circuitry work, class D amplifiers boast an efficiency of 90 to 95%. One of the biggest reasons for this incredibly high efficiency is the fact that the output transistors do not retain any electricity when they’re turned off. Hence no idle electricity is converted to heat.
What To Consider Before Buying A Car Amplifier
There are a few main factors to pay attention to while you’re shopping for a new amplifier. These will be vital in figuring out whether a particular amplifier will be a good fit with your existing car stereo:
Like with any electronic device, your speakers have a maximum threshold when it comes to the amount of power they can ‘handle’. Hence, you don’t want your amplifier supplying more than they can handle. There are two main metrics that measure power-handling in speakers: maximum RMS and peak power-handling.
Maximum RMS indicates the maximum amount of power (in watts) that you can safely supply to a speaker on a continuous basis. On the other hand, peak power-handling tells you the absolute maximum quantity you can direct to a speaker before its internal components start to fry. The latter basically marks the ‘point of no return’.
Power-handling is a useful metric because it determines whether you can hook up an amplifier to your speakers without any problem. You should only buy a very powerful amplifier, and make sure that your speakers have a high power-handling rating (especially a high RMS). Otherwise, you’re risking damage to the latter every time you crank up the volume on your stereo.
Power is pretty much the reason you would buy an amplifier in the first place. When your stereo and speakers seem unable to pump out music as loud as you want it (without distorting), then you usually bring an amplifier into the mix to give a clean boost to the signal.
Generally speaking, 10 watts is plenty loud for listening to music inside the car. It’ll certainly help to drown out any pesky road noise or engine rattles on your commute. Ideally, you should be looking at your speaker’s sensitivity rating before you determine how much power you need.
Speaker sensitivity measures how loud a speaker can get (in decibels) when supplied with one watt of power. For instance, if your speaker’s sensitivity is rated at 85 dB, then that means it’ll get moderately loud with just one watt driving behind it. With each additional watt, you add 3dB to the volume.
Essentially, the higher the speaker sensitivity, the lesser the amount of power you’ll need to reach loud volumes.
Generally, the frequencies you hear in music are between 20 Hz to 20,000 Hz. If you like hearing all the details come through in your music then you’ll need an amplifier whose frequency response spans this entire spectrum. Otherwise, certain low-end or high-end signals might be ignored by the amplifier while others are boosted.
However certain amplifiers are designed to only work with sub-woofers which means they’ll only handle the bass frequency range (between 20Hz to 250Hz). Hence, you must always pay careful attention to the frequency response before you buy an amplifier.
The Number Of Connections
If you plan on plugging in a range of audio devices to the amplifier, then you’ll need an amplifier with a versatile I/O (Input/Output) panel. For instance, if you need to connect an iPod, you’ll need a 3.5mm port. Likewise, you’ll need a USB port for your phone, tablet or a laptop.
While Class D amplifiers are quite small, you may have to target particularly small ones if your car has a cramped interior. Class D amplifiers can vary in size, from ones that can conveniently fit under seats to units that’ll need to be tucked away in the trunk.
Class D Car Amplifier Reviews
Now that you’re well aware of what exactly class D amplifiers are and what to consider when buying one, let’s take a look at my top five picks for this year:
- 300 Watts x 1 @ 4-Ohms, 500 Watts x 1 @ 2-Ohms, Frequency 20Hz to...
- Onboard 12dB/octave LP/HP/AP crossover & Infrasonic filter. Power Wire...
- On-board Punch EQ with +18dB boost at 45Hz. Input Sensitivity: 150 mV...
- Cast Aluminum Heatsink with Stealth top mounted control panel
- Includes wired remote (Punch Level Control). High efficiency amplifier...
Rockford Fosgate R500X1D’s frequency response is 20 to 250 Hz which means that it’s designed to work with subwoofers only.
The Rockford Fosgate R500X1D’s can power a single subwoofer with up to 500 watts RMS, meaning that you could blow out your eardrums if you really wanted to! Not all subwoofers can handle 500 watts on a continuous basis so make sure yours is able to before you purchase the R500X1D.
Variable Low-Pass Filter
Low-pass filters allow low-frequencies to pass through while blocking higher-pitched ones. These allow you to achieve a more bass-heavy sound while cutting out fizziness in the upper-bass frequencies. The Rockford Fosgate R500X1D’s variable low pass filter allows you to manipulate frequencies between 50-250 Hz, which covers the entire spectrum from sub-bass to upper-bass.
If you listen to electronic music with a lot of low-thumping beats, this low-pass filter can help you clean up some of the white noise or unwanted distortion from the bass.
If you’re a dubstep, synthwave or techno guy, then the Rockford Fosgate R500X1D’s bass boost may come in handy. It lets you boost up the 45Hz sub-bass signals by up 12dB. The result is a really rich, reverberating bass that you’ll be able to ‘feel’ as much as ‘hear’.
The Rockford Fosgate R500X1D measures just 8 ½ inches in width and 2 inches in height, meaning you could easily fit it under a car seat.
In addition to the efficient class D circuitry, the R500X1D sports a couple of other features which helps immensely with heat-resistance. First of all, the heavy cast aluminium chassis absorbs heat away from the internal components. This means that you can use it for a long time without causing any damage. In addition to this, the R500X1D has sensors which monitor both the output current and power supply temperature, making sure that the variations in the amplifier’s resistance or circuit issues will not cause any heat-damage.
- Very high-powered
- Low-pass filter helps to clean up the bass frequencies
- Bass-boost gives the low-end more punch without any loss in clarity
- Small enough to fit under a car seat
- Only works with subwoofers
- Perfectly suited for your desktop or a smaller space in your home or...
- 100W MAX Power Output X 2(4 ohms, 20 Hz - 20 kHz, 0.04% THD), comes...
- Simple compact design but practical and powerful; No pop, no audible...
- Home small hi-fi integrated amplifier, Sturdy, Lightweight, Aluminum...
- Manufacturer-Direct, free lifetime technical support, and 18-month...
With a rating of 100 watts RMS, this amplifier is much less powerful than the Rockford Fosgate R500X1D. However, it’s still got more power than the average person needs, especially if you’re pairing this up with a sensitive speaker! I don’t recommend having it cranked all the way up unless you want to deal with tinnitus!
Wide Frequency Response
Unlike the R500X1D, the Fosi Audio TB10A covers the entire spectrum from 20 Hz to 20kHz. This meant that I could boost the levels of all frequencies from sub-bass all the way to the upper treble signals.
Measuring just 4.2 x 3.5 x 1.4 inches, the Fosi Audio TB10A can easily fit under a car seat. Plus it weighs just 1.9 pounds, making it one of the most lightweight amplifiers I’ve come across.
One feature I absolutely love about the Fosi Audio TB10A is its Bluetooth compatibility. Not only does it let you connect your phone and portable music playback devices, but it also allows you or someone else to control the amplifier from a distance, without having to lean over and fiddle with it while you’re driving.
Like the Rockford Fosgate R500X1D, the TB10A features an aluminium chassis as well. This means that any extra heat will be rapidly absorbed by the exterior, preventing the internal components from getting fried.
- Enough power to split your eardrums
- Can handle the entire spectrum from bass to treble
- Fits under car seats and hardly weighs anything
- Bluetooth compatible
- Heat tolerant
- Not compatible with powered speakers
- This class D amplifier Supports USB coaxial analog Bluetooth and two...
- With amplifier output port, 3.5mm headphone jack and subwoofer...
- Customized BT4.2 Bluetooth module, Supports apt-X, easily connect with...
- The Bluetooth amplifier uses tas5508c+tas5342a from TI as amplifier...
- What you get: SMSL AD18 amplifier, 24V power supply us Plug, Micro USB...
80 Watts RMS
80 watts might not sound like such a big deal when compared to the previous two amplifiers, but remember that each watt corresponds to an additional 3dB in volume. Hence, 80 watts is more than enough to be able to really blast your music.
Like the Rockford Fosgate R500X1D, the SMSL AD18 is a subwoofer amplifier which means it only handles frequencies in the bass spectrum.
The SMSL AD18 comes with a 1.44-inch colour display, which is one feature that you don’t see on a lot of amplifiers. I found that the display was quite useful when trying to keep an eye on the output level. This prevented me from having to lean in and look at the dial while I was driving.
Bluetooth 4.2 supports AptX which is a transfer higher-quality audio file transfer protocol. Bluetooth has limited bandwidth which means that audio files have to be compressed before they’re sent to a device. With AptX however, the amount of compression occurring is much less. As a result, your music will sound significantly better and more nuances will come through.
In addition to Bluetooth, the SMSL AD18 also sports a micro USB input and a headphone jack as well. The former is handy if you’ve got your playlists saved on a USB stick instead of your phone and the latter allows for private listening even if you haven’t got a pair of Bluetooth headsets.
The SMSL AD18 is actually 0.6 pounds lighter than the Fosi Audio TB10A. Plus it’s incredibly compact too; certainly small enough that you can fit it under a car seat with room to spare.
- Enough and more power output
- A handy coloured display
- Bluetooth 4.2 with AptX
- Only works with subwoofers
- |BLUETOOTH 4.2 CONNECTIVITY| – your portable Bluetooth micro...
- |DUAL CHANNEL CLASS D BLUETOOTH AMPLIFIER| – your portable...
- |WIRED SPEAKERS INTO BLUETOOTH SPEAKERS| – with your micro...
- |ILLUMINATED HEAT SINK & FRONT PANEL| – with its illuminated heat...
- |DUAL LU SPEAKER LINE| – don’t forget to add the top selling...
25 Watts RMS
The Dual Electronics DBTMA100 power-output is rated at 25 watts RMS for each channel, with a peak power rating of 50 watts. While it probably won’t get to the same ‘ear-splitting’ levels as any of the amplifiers above, you can certainly get loud enough to cut through pesky road noise. Pair it up with a sensitive speaker and you can still blast your music without a problem.
Wide Frequency Response
The DBTMA100’s frequency response spans from 20Hz all the way up to 22,000 Hz. If you listen to music with a ton of high pitched vocals and ‘squealing’ distorted guitars, then this amplifier can boost those elusive upper-treble frequencies. So regardless, of how loud you get, you won’t have to deal with any white noise or silent spots.
Bluetooth 4.2 allows connectivity up to 100 feet. So whenever I stop at a gas station and I’ve got my phone connected to the amplifier, I can still have the music playing for my kids even if I step out of the car.
The DBTMA100 is one of the most visually striking class D amplifiers I’ve come across. Blue LED rings light up behind the knobs on the front panel as soon as you turn it on. Not only does this look cool, but it can also improve visibility in low light conditions. In addition, the heat sink lights up in red which contrasts nicely with the blue.
The DBTMA100 is just 4.2 inches wide and 5.8 inches tall, which means that it can fit under your seat regardless of how small your car is.
- Wide frequency response
- Bluetooth compatibility
- Visually striking
- Doesn’t offer the same level of power output as the other amplifiers on this list
- Class D MOSFET Monoblock Power Amplifier
- Peak Power at 1 Ohm: 388 Watts | RMS Power at 1 Ohm: 350 Watts
- Frequency Response: 20Hz - 250Hz, On-board Bass EQ Switch with +6 or...
- Featuring 4-Way Protection Circuitry and 8 AWG Power & Ground Input...
- Stable at 1 ohm | Remote Subwoofer Level Control Included
Bass Frequency Response
The Skar Audio RP-350.1D’s frequency response spans between 20Hz to 250Hz which means that it’s a subwoofer amplifier.
On-Board Eq Switch
The RP-350.1D features an EQ switch that provides either a 6+ or a 12+ dB boost at 45Hz. This is useful if you listen to a lot of bass-heavy genres like dubstep or techno. 45Hz is in the sub-bass range so boosting it up can make those really low beats sound especially massive.
The Skar Audio RP-350.1D is capable of outputting 350 watts on a consistent basis, which puts it in the same league as the Rockford Fosgate R500X1D. If you’ve got a subwoofer with low-sensitivity, then purchasing a high-powered amplifier like this is probably the best way to go. However, make sure that your subwoofer can also handle this much power. We’d recommend only buying the RP-350.1D if your subwoofer has an RMS rating of 400 watts or more.
The RP-350.1D features a thick metal outer shell, meaning you could probably drop this thing on a concrete floor without even denting it. You can certainly be set it up on an off-roading vehicle and not worry about it getting damaged as you drive through rough, jagged terrain.
This amplifier contains a heat-sink designed to draw away heat from its internal components. This is very useful if you tend to listen to music a lot in the car because you won’t end up shortening the amplifier’s lifespan while doing so.
- Bass-boost for bringing out the ‘thump’ in the low end
- 350 watts RMS
- Extremely durable metal construction
- Heat sink protects components from heat damage
- Larger than all the other amplifiers on this list
The Best Overall Class D Amplifier
All of the amplifiers in the top five are excellent, which made picking my overall favourite a difficult task. I knew I wanted something which could handle the full frequency range so that shortened it down to the Dual Electronics DBTMA100 and Fosi Audio TB10A. After a lot of tossing and turning, I finally decided to go with the Fosi Audio TB10A.
What settled the argument finally was the power output. The TB10A has an RMS rating of 100 watts which meant that I could switch my speakers whenever I felt like it without having to worry about its sensitivity rating.
Bluetooth compatibility was a big plus since I didn’t want to be restricted in terms of what kind of devices I wanted to pair up the amplifier with. Plus, it allows me to go wireless and have the amplifier mounted anywhere and still be able to connect to it. Lastly, I listen to music a lot inside the car so the good heat-dissipating ability is a must, which the TB10A has no lack of.
Frequently Asked Questions
Which Class Amplifier Is Best?
It depends on what you’re concerned with. If you want the purest possible signal, then Class A amplifiers are what you’re looking for. However, the trade-off is efficiency. On the other hand, Class D is highly efficient but lacks purity when compared to Class A amps.
Are Class D Amps Good For Subs?
Class D amplifiers like the Skar Audio RP-350.1D are designed specifically for boosting subs.
How Do I Choose An Amp For My Subs?
The frequency response will indicate whether or not an amplifier can work well with a subwoofer. If the cutoff is above 60Hz, then it’s not going to be able to handle the sub-bass range of frequencies.
Why Does My Amp Get Hot So Fast?
Class D amplifiers don’t typically get hot fast. However, if yours does, then it could be due to a couple of reasons. First of all, check how the amplifier is positioned. Heat rises so make sure that the amplifier isn’t placed upside down or under a carpet. The latter will cause heat generated from components under the car to be absorbed by the amplifier. If your amp doesn’t have a heat sink, then it can heat up quickly as well.
Does A Car Amplifier Improve Sound Quality?
Car amplifiers boost the levels in an audio signal and can help you cut through ambiance. However, car amplifiers are not equalizers, meaning that they don’t particularly help you shape your tone.
The products featured on this page were last updated on 2020-03-06 at 20:12 /. Affiliate links / Images from Amazon Product Advertising API.