In the audiophile world of high-fidelity speakers, you can find JBL speakers almost everywhere, so it only makes sense that you'd also find them in cars. For this review, we tested and evaluated the best 6 x 9-inch speaker in each series – in this case, the GTO939. When we tested this model, we found that while it’s certainly a good speaker for the price, it doesn't provide high-end performance.
I tested audio quality by playing a 20Hz to 20kHz sine tone through each speaker and using a frequency analyzing plugin to analyze and grade the speaker’s ability to accurately reproduce low, mid and high frequencies. In this test, the JBL GTO 6 x 9-inch speaker received all B's.
It earned a B+ for its high-frequency reproduction, which is good considering how difficult it is for speakers to accurately produce that range. While it isn’t as good as the Alpine Type-S or the Infinity Reference X speakers, the high notes it projects are good enough to not be a distraction – they don't grate on your ears or lead to ear fatigue or headaches, which happens when highs are not balanced or inaccurate.
The GTO939 received B- grades for the midrange and lows. It wasn't the worst performing speaker in our tests, and in fact, it sounds okay – it just doesn't stand out. The speaker sounds average, but for the price, it's a good option.
Another reason the JBL GTO speaker sits right in the middle of the pack is because of its comparative loudness, which it received a B for. It was above average but not as loud as you'd expect a speaker with a 94 dB sensitivity rating to be. To determine this grade, I measured the volume produced by the speaker at four levels on a car stereo, and I did the same for each speaker we reviewed. Since they were all supplied the same amount of power from the same stereo, I could easily compare which speakers were more efficient at converting power to volume.
The GTO939’s best power handling feature is its 200 RMS watt continuous power handling. This is the highest continuous power handling specification we saw by 50 watts. When you combine this with the high efficiency, you have a car speaker you can really turn up without fear of clipping the tweeters and damaging the woofers.
One minor downside is the speaker’s below-average peak power handling of 300 watts. Generally, you want the peak power handling to be at least twice as high as the continuous power handling so you have enough room for spikes in the music to occur without damaging the speaker.
The GTO series has speakers for every installation size, from 3.5-inches to 6 x 9-inches. Each one is made with a carbon-injected woofer on a fiberglass-reinforced poly frame. Remember, it's important to measure the speaker installations on your car before purchasing replacements.
The JBL GTO series car speakers are among the most popular, but they’ve also been around for a long time. This is starting to show as other speakers surpass them in audio quality and efficiency. However, the series’ models still have high-end power handling specs, and their audio quality is good, which makes them an excellent option for upgrading your factory-installed speakers.