After over 60 hours of research and eight hours of testing audio quality and volume potential, our pick for the best coaxial car speaker series of 2021 is the Alpine Type-S. The series’ 6 x 9-inch speaker produced the best audio in our tests and was among the most efficient at converting power to volume. In addition, the series has speakers in sizes that fit most installations, making it one of the most versatile on the market. If you’re looking to up your car’s audio game, the Alpine Type-S series is a good place to start.
Best Car Speakers
Alpine Type-S / SPS-619
The 6 x 9-inch coaxial speaker from the Alpine Type-S series, the SPS-619, emerged from our audio quality and frequency accuracy tests with the best overall performance. Even its comparative loudness was among the best. When you consider its affordable midrange price and size selection with options to fit most installations, it’s clear why this is the best car speaker series.
For our tests, I recorded each car speaker playing a 20Hz to 20kHz sine tone, then I used a frequency analyzing plugin to grade how well the speaker reproduced the tones in the high, mid and low frequency ranges. The Alpine SPS-619 received an A+ for the high frequencies, an A- for the midrange frequencies and an A for the low frequencies. In addition, it received the best grades in our subjective ear test. There is no such thing as a perfect speaker, but, to put it simply, this one sounds the best. The SPS-619 has better speaker efficiency than its 90 dB sensitivity rating suggests – it received an A- for comparative loudness in our tests. To test this, I hooked each speaker up to the same car stereo. I then placed a decibel meter 1 meter from the speaker and used it to measure the sound output at four volume settings on the stereo. This test allowed me to gauge how efficiently each speaker converts power to volume. My results show this Alpine model doesn’t need as much power to reach high volumes as most other speakers, which is important because its continuous power handling specification is below average, at just 85 watts
- Highest grades for audio quality
- Comparatively loud
- Sizes available for all common installations
- Power handling specifications are below average
- Frequency range is relatively narrow
- Lacks style
Infinity Reference X / REF-9623ix
The Infinity Reference X series has routinely been among the best car speaker series we’ve reviewed and tested, and this year is no different. The 6 x 9-inch Infinity REF-9623ix speaker received excellent grades for audio performance and tied for second in our comparative loudness tests. When you compare these test results with its power-handling specifications and low price, the Infinity Reference X series is the best option for value.
In our frequency accuracy tests, the REF-9623ix received an A+ for the high frequencies, an A for the midrange frequencies and a B- for the low frequencies. Overall, it received an A- for audio quality. Compared to the other car speakers we reviewed, it is clearly one of the best sounding coaxial speakers on the market. The REF-9623ix has a sensitivity rating of 94 dB, which is the highest of the speakers we reviewed. However, high sensitivity ratings don’t always mean good volume. This speaker was one of the few that lived up to its sensitivity rating in our comparative loudness test, receiving an A. Only the Pioneer PRO speaker produced greater volume using the same amount of power.
- Very affordable
- High-end audio quality
- Very efficient at converting power to volume
- Bass isn’t great
- Series lacks component speaker options
- Lowest frequency response is just 46 Hz
Pioneer PRO TS-6900PRO
The Pioneer PRO series of car speakers is one of the newest to hit the market. The blade-like grille and shotgun barrel tweeter give it an aggressive look, but it’s the speaker efficiency that really adds teeth. In our comparative loudness tests, the TS-6900PRO, the 6 x 9-inch speaker from the series, was the loudest – it projected at higher volumes than other speakers when set to the same power output on the stereo.
To test comparative loudness, I used the same car stereo to power each speaker. I measured the volume by placing a decibel meter 1 meter from the speaker and playing sound at four volume settings. This puts the speaker’s sensitivity specification to the test in an everyday scenario, and the results show the Pioneer PRO is significantly more efficient than most car speakers. For example, at half volume, the PRO produced 93.8 dB, which was almost 6 decibels higher than the average. In our frequency accuracy tests, the TS-6900PRO received an A for the high frequencies, a B for the midrange frequencies and an A+ for the low frequencies. Overall, its audio quality received an A, making it one of the most accurate and best sounding speakers we tested. To put it simply, this speaker bites, but it doesn’t sacrifice audio quality to do so.
- Best at converting power to volume
- Received an A for overall audio quality
- Has peak power handling of 600 watts
- Series lacks common installation sizes
- No component speaker options
- Style might be too aggressive for some people
Why Trust Us
We has covered car speakers since 2011, but I’ve been reviewing and testing them since 2013. Each year, I devote up to 80 hours to researching and testing the most popular coaxial speakers on the market. I’m continually looking for ways to refine my testing methodologies with the use of both technology and practical application.
I’ve held an interest in the physics of audio reproduction since the late 1990s, when the band I played in at the time went into the recording studio for the first time. I found myself fascinated by the science involved in both the production of audio and the recording of audio. Since then, I’ve spent a summer as the sound guy at a local venue, my bands have recorded five albums, and I’ve personally recorded an additional six solo albums with my own equipment. In other words, I bring over twenty years of experience with recording, mixing and analyzing audio frequencies to my reviews of car speakers and car audio.
My car audio experience began when I purchased my first car in 2002. The car, a 1987 Honda Civic CRX, cost me just $1,200 and had over 250,000 miles. The suspension was shot and the gas mileage wasn’t great, but the sound system was amazing. It came with four high-end component speakers, an external power amp and a 15-inch subwoofer. In fact, the sound system was the reason I purchased the car. It was a stereo on wheels. This is how I’ve viewed my cars ever since.
How We Tested
The best car speakers have two things in common: great sound and great volume potential. You want a speaker that sounds better than your car’s factory-installed ones and doesn’t require an external amp to reach ear-splitting volumes.
Here is how I tested these characteristics:
There is no such thing as a perfectly accurate speaker because there are too many variables that affect a woofer’s ability to produce sound, such as humidity, altitude and air pressure, to name a few. Still, a good sounding speaker is one that produces the audio signal it receives as accurately as possible. And if you compare all the speakers in the same environment, you can find the ones that perform more accurately. This is exactly what I did.
To test performance, I created a 10-second sine tone that transitions from 20Hz to 20kHz, which is the optimal range of human hearing. I set up a microphone exactly 12 inches from the center of the woofer and had the speaker play the sine tone repeatedly for five minutes as I recorded the results. Then, I used a frequency analyzing plugin to create the average frequency signature of the speaker. Since the audio signal of the sine tone has no variations, I compared this average frequency signature to the original audio signal. By counting the peaks and valleys and considering the degree of decibel fluctuation in these variations, I could determine how accurate a speaker was at reproducing an audio signal compared to other speakers producing the same frequency.
To account for personal preferences, I graded each frequency range separately. Some people prefer punchy bass, clean highs or detailed mids. These audio preferences are largely dependent on the recording, mixing techniques and music style, not the speaker performance. That said, a high grade suggests that the speaker is more likely to produce the intended audio signal. So, if you listen to music with a lot of bass, then a speaker with a high low-frequency grade is your best option.
Sensitivity is a specification audio experts, and speaker marketing departments, point to as one of the most important to consider when buying a speaker. This is because it tells you how efficient the speaker is at converting power to volume, and sensitivity can make a big difference in your listening experience. However, there is a lot of debate within the audio community over whether these sensitivity ratings are as accurate as the manufacturers claim. This was confirmed when I talked to car audio experts at the Sound Warehouse in Ogden, Utah. They warned me to take the speakers’ sensitivity ratings with a grain of salt because there isn’t an industry standard for measuring it and manufacturers publish the rating that looks the best.
So, with the same car stereo to powering each speaker, I used a decibel meter to gauge the highest volume each speaker produced when the stereo’s volume was set at levels 10, 20, 30 and 40. I set up the decibel meter on a tripod placed 1 meter from the woofer.
The greatest efficiency variation occurred at levels 10 and 20. At level 20, the most efficient speakers, like the Pioneer PRO, produced volumes nearly 6 dB higher than the average, which is a huge difference in power efficiency. (Every 3 dB increase in volume requires twice as much power. So, for example, an average speaker would need almost 100 watts to reach the same volume as the Pioneer PRO did at 25 watts.)
Some of the speakers we tested were as efficient as their sensitivity rating suggests. Some were better. Others were not even close.
Car Speakers: Additional Tips for Improving Your Car Audio
As part of my research, I consulted with Steve Stern, president of the Mobile Electronics Competition Association, which puts on car audio competitions, about how you can best improve your car audio. He started off by stating that the most important consideration when upgrading your car speakers is to make sure your new ones are compatible with your existing equipment and your future A/V system plans. But, he also warned that you get what you pay for and argued that a professional installation is the best way to get the most out of your car audio. He suggests that “a tight install can work to bring out the best in even the most basic, inexpensive equipment. A weak install can bring unacceptable, compromised results with the most expensive and highly lauded speaker.”
Here’s some tips on making sure your new car speakers are compatible with your current system:
Impedance is the speaker’s electrical resistance. It doesn’t make a difference to audio quality or performance, so long as it’s matched to the impedance rating of your car stereo or amplifier. The lower the impedance, the more the speaker draws power from the source. As a result, an amplifier with a high impedance could burn out trying to power a speaker with a low impedance. Conversely, a speaker with a high impedance isn’t designed to handle the power of an amplifier with a low impedance.
Speaker’s range in sizes between 3.5 inches and 6 x 9 inches. Every speaker series we reviewed has multiple sizes but few have all the sizes. As such, it’s always important to check your car’s speaker sizes before purchasing replacements.
If you’re installing the speakers yourself, it’s a good idea to purchase a speaker bracket. Unfortunately, car manufacturers don’t have a standard cutout for speakers, which means the holes for the screws might not match up with the after-market speakers. Universal speaker brackets, which come with many car speakers, are an easy fix for this problem. They can even allow you to fit a smaller speaker into a larger cutout.
Component vs. Coaxial
We reviewed coaxial speakers, but if you want the absolute best car audio experience, then you should look into component speakers. Coaxial models consist of a woofer and at least one tweeter built into the speaker, usually on a bridge or cone. With this design, the woofer creates the low and midrange frequencies while the tweeter creates the high frequencies. With component speakers, the tweeter is built into a completely different speaker, which is installed in a separate location.
Component speakers are more accurate because the woofer and tweeter aren’t competing to vibrate the same air. They also allow you to customize the audio to fit the acoustics of your car. However, component speakers cost a lot more than coaxial speakers, and they usually require professional installations. There is a great deal more wiring required, and you may even have to create new installation areas for component speakers unless your car has spaces for tweeters.