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JBL GTO620 review. Are JBL Stadium speakers really that good?

We have recently replaced factory speakers in a friend’s car and the speakers we chose were JBL Stadium GTO620.

Before installation, we did detailed research to find out if the GTO620 are ant good? Let’s find out.

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GTO620 from the Stadium series offer quality, which you can find in only a few top and much more expensive brands in the World. Their sound quality is simply excellent with crisp and clear tones. Bass in GTO620 is strong and deeper than in similar models, and high tones can be extended by 3dB, by pressing a little button on the tweeter. Also, tweeters, same as in the classic GTO629, can be adjusted to better direct sounds towards the ears.

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The article below will show more details about the design, functionality, and connections of these fantastic JBL speakers.

Why did we choose JBL Stadium GTO620?

JBL GTO620 are successors of the legendary JBL GTO629, which still today play the highest quality music in thousands of cars. JBL, as a company, is well known for making quality products. If their speakers are at the top of the recommendations continuously for many years, they have to be really good.

are JBL GTO620 good speakers

GTO620s are coaxial full-range speakers that were designed to create clear, crisp sound. These premium speakers have been developed for demanding customers, and people do not complain about sound quality. I also used to have older GTO629s in my rear doors, and they played beautifully. GTO620s continue this tradition from the JBL premium line. 

JBL Stadium series compete with top-class speakers like JL or Focal, but they are offered for much less price, and this low price is a massive advantage of GTO620. We spent over a month doing research, and we were listening to over a hundred different speakers, but we could not find a better sound in 2-way coaxial speakers within this price range.

The best place for JBL GTO620 are the door, and depending on how you are developing your car audio system, they can be installed in either front or rear of the car, although not all cars have room in the rear door for 6.5″. I saw vehicles with two pairs of Stadium GTO620s speakers, and music experience was outstanding.

JBL GTO260 have robust design

JBL GTO620 is a decent set of speakers made of high-quality materials. Instead of a cheap steel basket, what they have is a large basket made of a combination of fiberglass and carbon.

Not many speakers have light and stiff cones that are capable of producing strong bass. JBL Stadium GTO620 have a cone made of fiberglass, which makes speakers solid with a long lifetime.

To feel how stiff the cone is, gently tap it with fingers and push it a little towards the magnet. You will be surprised by the amount of smooth movement. Most car speakers have coated paper cones that will not survive in rough conditions. GTO speakers are different, and if installed correctly, they will last for many years.

Also, the surrounding was not left behind. In all JBL Stadium speakers, you will find butyl rubber around a cone, and a soft dome tweeter.

The most critical factor for the majority of users is how long their speakers will last, and GTO620 proves to be long-lasting speakers made from the highest quality materials. 

From the outside look, another well-made element is magnet cover. It is made of solid material and protects the magnet from mechanical damage, as well as from moisture that often occurs inside the door.

Any water drops will drip on the carbon basket rather than directly on the magnet. This is especially important in areas with a lot of rain or long winters, and when your car is not a brand new anymore and its windows seals can be torn.

UniPivot technology makes tweeters adjustable.

When you look at the speaker from the front, it is not a larger PlusOne cone that you notice first, but adjustable tweeters made in the UniPivot technology that produce extraordinary high sounds, even at the highest volume.

Thanks to exclusive for JBL UniPovit, you can better direct the high tones towards the ears; however, the adjustment angle of the tweeters could have been higher.

JBL GTO620 adjustable tweeters

A higher adjustment angle would help high sounds be better heard in the upper part of the cabin, especially when speakers are placed in the lower part of the door, and this is the only point I would change in the design.

To balance it out, you can increase the volume of the high tones, which is a massive plus towards GTO620s. By pressing a small silver button on the tweeter’s housing, you make treble clearer and twice as loud with an additional 3dB. 

Easy installation

An additional benefit of GTO620 car speakers is their easy installation. In the package, you will find the adaptor rings that will fit several car types. Also, we were surprised when we saw quality mounting screws in the box. 

Although you may need to purchase additional rings if you want to change the speaker’s size in the car, replacing standard 6.5″ with GTO620, replacement is straight forward. 

Depending on the installation type you have in the car, you may need to purchase a speaker wire extension to match with standard wire cubes. 

JBL GTO620 speakers in car door

Power range

The JBL GTO620 speakers have a peak power handling of 225W per speaker or 550W for the pair. The continuous RMS power is 75W per channel.

75W per channel means they do not need a lot of power from the amplifier. The stock head unit can power GTO620. However, when you want to hear how incredible sound quality they can produce, it is worth to match them with an external amplifier.


People often ignore sensitivity, but in the case of car speakers, it is more important than many realize. The sensitivity rating shows how the speaker will respond to power. In other words, the higher the value, the better the response.

Sensitivity in GTO620 has an outstanding value of 95 dB, which means they will be twice as loud as the 92 dB speakers when powered from the same source. 

Or, when you use a 100W amplifier for the GTO620s, you need a 200W amplifier for speakers with 92 dB sensitivity to make them play at the same volume level. Bear in mind that the vast majority of the factory-installed speakers have sensitivity around 86 – 88dB which means, JBL GTO620 are four times louder even when powered from the same factory head unit. 

Do I need an amplifier for JBL GTO620 speakers?

JBL suggests for GTO620 power range between 25 and 180W, and that means either a head unit or external amplifier will be sufficient to power these speakers.

Although many people install JBL Stadium speakers with amplifiers, which is fully understandable, amplifiers are not needed to power them if you have a head unit that makes more than min. 25W per channel. 

If you decide to use an amplifier, you will have a little stronger bass, but you do not have to go extreme with the amplifier’s power. A few years ago, I used for older GTO629s, 2x120W Lanzar, and this was more than enough for a small roadster with only two speakers the doors.

However, you do not have to use an amplifier for GTO620s. Lightweight cone, together with outstanding sensitivity of 95 dB, make Stadium GTO620 speakers play beautifully without a lot of power.

Another plus for JBL is their Plus One+ woofer technology that makes cones extended to the edge of the basket. This extension makes a large cone’s area, which means you will hear even stronger bass, and the lows in GTO620s are stunning.


JBL Stadium GTO620 speakers are designed to replace factory speakers. Similar to other speakers from Stadium series, GTO620s offer a great improvement to the car audio that being appreciated by demanding audio enthusiasts.

These speakers are able to create theater-quality sounds, and it does not matter if installed in a small or large car. GTO620s are featured with a carbon-injected Plus One™ woofer cone with the expanded area, supported by butyl rubber surround for long-lasting performance. 

Also, JBL GTO620 car speakers are equipped with edge-driven, balanced dome tweeters designed to provide quality of highest frequencies. These tweeters are made in JBL’s patented UniPivot™ technology allowing you to direct treble precisely towards the ears. Also, you can boost high tones by 3 dB to match your needs.

JBL GTO620, although they do not have extreme power, with 75W RMS, offer unusual sensitivity of 95dB what makes them louder than most of the speakers in this size. With such high sensitivity, they do not require a lot of power. They can play amazingly from a car stereo; nevertheless, when you want to hear their real hi-end quality, it is recommended to use an external amplifier.