JL Audio made its name in the subwoofer category. They are well known for providing a quality product at a competitive price. With a strong network of independent dealers they are a little harder to find, but well worth the search. If you want clean concise sound with a strong heritage of winning in car audio competitions JL Audio is where you should look.
I think the biggest advantage that JL’s midwoofers have comes from their “Elevated Frame” cooling system which was used first on their revolutionary W7 woofers. This design allows air to flow across the top-plate and onto the voice coil windings of the midwoofer. Keeping a midwoofer cool is important because it allows the speaker to work the same and sound the same in all sorts of stressed situation. Therefore the sound is the same quality regardless if it is being played quietly or loudly.
JL couples their innovative midwoofer design with a conventional one-inch aluminum dome tweeter with a twist. They use soft rubber as a surround and also have Nomex as a voice coil former, which helps to “voice” the tweeter with the midwoofer. In other words, the sound blends to give a solid yet clean sound in the range between the two speakers.
Because of the overall design and technology and clean design this series rounds out my top five.