PROS / It's very good at producing accurate frequencies, and the overall audio quality is good.
CONS / The tweeter bracket isn't adjustable.
VERDICT / Everything about the Polk db series of car speakers is above average – the audio quality, frequency accuracy, comparative loudness and power handling. It's one of the best car speakers available.
When you name a series of car speakers after the abbreviation for decibels, you're telling people who buy these speakers one thing – turn it up! This is exactly what you get with Polk's db series of auto speakers. While it didn't post the loudest volume in our comparative loudness tests, it was certainly loud. While the midrange frequencies were just average, the low and high frequencies were very accurate. In addition, the power handling is excellent. In the db series, you'll find speakers for every size installation except the 6 x 8-inch. For the sake of this review, we tested and evaluated the 6 x 9-inch car speaker – db691.
To find the best car speaker, we tested the db691 in comparison to the top car speakers on the market by performed frequency accuracy tests, subjective ear tests and comparative loudness tests. With the frequency accuracy tests, we recorded it as it played a tone that moved from 20Hz to 20kHz. Then we graded the low, mid and high frequency ranges. Though no speaker is perfect, the best car speaker should play an audio signal as accurately as possible. We also performed subjective ear tests by having listeners rate the speakers as they listened to music. Finally, we measured the decibels at 1 meter that each speaker produced when the amplifier's volume was equal. This test showed how efficient each speaker was at converting power to volume.
In the frequency accuracy tests, the Polk db691 received an A- for both the low and high frequencies. We gave it a B for the midrange frequencies, which was average. These grades reflect a speaker that is above average overall. This accuracy was reflected in the subjective ear tests, where it received good marks overall.
In the comparative loudness tests, the Polk db691 was measured at 2 dB less than the loudest car speaker in our tests, which was also 1 dB above average. For comparison, the least-efficient speaker in the loudness tests was 4 dB below the db691. In addition, the continuous power handling is above average at 125 RMS watts. This allows you to turn it up without experiencing distortions to the audio. Even the 300-watt peak power handling gives you ample room to handle loud peaks in the audio without clipping the speakers.
The one significant downside to the Polk db series is the lack of an adjustable tweeter. The tweeter bracket is fixed to the frame, which doesn't allow you to aim it for optimal positioning. This is a minor flaw to an otherwise excellent design.
The Polk db series of car speakers have the necessary loudness and power-handling ratings to handle heavy loads and loud volumes. The db691 6 x 9-inch speaker was above average in nearly every aspect but never spectacular. This series of car speakers makes for an excellent upgrade for your factory-installed speakers.