THX announced this morning that it certified an audio system available in the BMW Z4, both the Coupe and the Roadster, under its THX Certified Car Audio program. That means THX engineers worked with BMW to design speaker arrangement, digital-signal processing (DSP), amps, and other components of the audio system to meet THX standards. It also means that an already exceptionally engineered car gets a superior audio system. The system, as designed for the Z4, uses 2 subwoofers behind the seats, 2 woofers in front of the car, and another 6 midrange speakers and tweeters placed around the cabin. That's 10 speakers in a two-seater cabin. Each speaker gets its own amp channel and DSP as well. The amp power adds up to 430 watts.
I've heard the THX system in the Lincoln Zephyr, and it is really elegant. It has extremely rich sound, all the ranges coming through crisply. Even at high volume, the system doesn't distort, and it's designed so that it can't destroy the speakers, leveling out any notes that exceed speaker tolerance. The DSP gives a lot of fine-tuning control over the system, which can adjust to compensate for road noise at different speeds. I'm intrigued that the Roadster and the Coupe have both gotten THX certification, because it probably means both Z4 versions have identical systems. In the Z3 Coupe, BMW took advantage of the hardtop by installing speakers in it and dropping a subwoofer facing into the rear cargo area, something impossible in the Z3 Roadster. That speaker placement results in very impressive audio. I'll try to arrange a drive in the THX-equipped Z4 and report back soon.