Ive read and heard about several car audio producers that make the "best" car audio speakers in the industry. But i studied the ESL home speaker systems from MartinLogan, and i firmly believe these are the best sound reproduction speakers available in the world. So why arent they made for car audio?
MartinLogans and ESLs are the best speakers for audio. There are a few things about ESLs you need to understand though. 1: the aren't very efficient. They demand a LOT of power to work at their best (think Krell pure class-A amplifiers) and the amplifiers have to be very fast as responding to the reactive load of the ESLs which, compared to a conventional speaker, can be pretty dramatic.
2: ESLs are bi-polar speaker panels. They produce sound equally from both the front and rear of the speaker, relying heavily on speaker positioning as well as room acoustics for ideal performance. half of the sound they produce is by first-order reflection off of the wall(s) directly behind the ESL panels. This is what gives them their warmth and realism, and the dispersion that makes them sound "real" and less easy to pinpoint exact driver locations. The thing is, that concept wouldn't work at all in a car for obvious reasons. 3: as noted above, ESLs are extremely sensitive to positioning, and must be placed precisely in a room to get their full effect. While they are magnificent speakers, they are also famously picky speakers about the room in which you place them, and the rest of the system powering them. You don't buy MartinLogans and run them on a Yamaha AV receiver. You get a good set of class-A amplifiers and a solid power supply for them, or they just won't sound as good as they should.
by the way the other problem I neglected to mention was size. the larger the ESL panel is, the better it's frequency response becomes. A normal ESL panel is usually about anywhere from 3'x1' up to 6'x4' or larger, and their response range is usually flat from 250Hz up to the 50KHz range. Below that 250Hz or so, they require conventional woofers to take over for the lower frequencies.
it'd look rather odd to have ESL panels in a car, when the panels would be the size of the car doors
then you have the distance involved. you need to be a number of feet away from the panels for them to sound right, and to achieve good imaging and soundstage.
Now you may want to look at magnetic-planar drivers which use a somewhat similar approach to sound as an ESL. They tend to be cheaper, and smaller, but still require 120VAC to charge the panels (yet another reason you won't see ERSL in cars.. 120VAC isn't easy to produce from 12VDC) and magnetic planars are made for PC speaker systems as well, by companies like Monsoon.
ESL works, as you're probably aware, by applying 120VAC to a conductive mesh screen. As that voltage is altered it causes the screen to resonate and produce sound. Lower frequencies require a lot of air to be moved, and ESL panels just don't move that much air, that slowly. It's easier to pair the panel up with a conventional woofer to cover the entire hearing range. Take the MartinLogan Odyssey for example. The speaker stands about 5'8" tall, weighs about 115lbs, and has a rather substantial base below the panel. That base houses one 10" and one 8" woofer for sub-bass frequencies, in a horn loaded enclosure. Very smooth, flat response, and blends well with the ESL, but that's what works for everything below 250Hz on those speakers. The Ascent uses a single 10" in each main.
wall-mounted ESL panels made by some companies, are almost always paired up with a subwoofer that covers the lower frequencies for the panels, where the panels are used for vocal ranges and above.
