JBL GTO625 Coaxial

Is it getting hot out there? Looking at this JBL coaxial, I think it is. The coaxial market is the meat on the mass-market bone. More coaxial speakers are sold every year than any other type of speaker. This is obviously due to the fact that you can just yank a stock speaker and screw in a coaxial.

For a while there, I considered coaxials malicious devils. They were designed to absolutely scream on the retail demo board commanding attention. That screaming, put into a car filled with glass, could create more ear-cringing pain than the sound of a dentist's drill.

Without giving everything away, these JBL GTO625 coaxials lay no credence to that stereotype. It makes a time-hardened car audio critic feel good to see bad designs die a terrible death.

The BasicsJBL's GTO625 is a 6.5-inch coaxial design with a poly cone and rubber surround. The tweeter is about three-quarters of an inch in diameter and is centered in the cone using a small standoff, common to most coaxial designs.

On the marketing-speak side, JBL talks of their Plus-One cone design. With a patent pending on it, the design is basically said to offer up to 30% more cone area than competing designs. Looking at the cone, the speaker does appear to go right to the edge, but not quite as far as on the speakers of JBL's sister company, Infinity.

However, measuring the cone from edge to edge, I came up with 4-5/8 inches. That is within a 1/16" of the norm for 6.5-inch coaxials made most everywhere. So while I did not find the cone to be a great deal larger than normal, I did find the looks very appealing with a design pattern that does an excellent job of simulating the woven look of glass fiber.

The tweeter uses what JBL calls an Edge-driven Kaladex dome. Broken down into plain English, this is a conventional dome driven by a voice coil that attaches to the outer edge of the dome. This is actually something of a switch because so many recent coaxial speakers are being built with balance mass construction. Balance mass tweeters can be identified by what looks like a quarter-inch ring around the dome. The advantage is typically a smaller magnet and higher efficiencies. JBL's Edge-driven is a very tried and true design with superior power handling and a generally smooth response.

The problem with many coaxials today is way that the mounting holes line up with factory mounts versus the positioning of the tweeter. Often, this sends the tweeter firing into an undesired area, and greatly reducing the high frequency output as they are very directional. JBL addresses that with a genuinely unique feature. The GTO625 and others in the GTO family, utilize a rock and rotate tweeter mounting design. Mounted on a stubby post, the tweeter can be focused towards the listener or at an angle that provides the best performance. Very nice!

Additionally, the angle on the tweeter is only good up to about 15 degrees. This design works well because JBL deliberately placed the tweeter electrically out of phase, but acoustically in phase off axis. In other words, the speakers were built to be heard off axis, not straight on. And since 99% of all coax speakers will be mounted off axis, the design is very smart. Allowing the tweeter to tilt further could create additional abnormalities in the response.

The stamped metal frame is plenty durable and the magnet is housed within a sleek looking plastic cover. A small capacitor gives the tweeter a 6 dB per octave roll-in. Power handling is rated at 60 watts continuous, 180 watts peak. The suggested retail for the GTO625 is a very reasonable $119.95.

InstallationInstalling the GTO625 into any vehicle with a six-inch factory opening is made easy. The GTO625 system includes the Intermount III mounting hardware; a complete set of rings to facilitate easy installation into nearly any car out there.