Subjective
The ATS 6.5s seemed a bit short on midbass output and just a little heavy on the top end. In a typical door or rear deck installation this may work to your advantage in some situations. However, in most cases, you’re going to need an EQ regardless of which speaker system or mounting location you use.

During the course of this evaluation, I tried all of the external crossover’s adjustments and finally settled on the “0 dB” tweeter setting with the tweeter’s polarity inverted relative to the markings on the crossover. Of course, these settings will differ with each individual install, but in our test enclosures, this arrangement seemed to produce the smoothest midrange response. The crossover’s internal high pass filter is set to about 65 Hz and has a measurable, but barely audible, effect. It’s most noticeable on program material with strong and relatively constant bottom end, such as boom tracks or even pink noise. Appreciable output below this cutoff frequency is exceedingly rare in a 6.5-inch speaker. If you were planning to install a subwoofer in the system, enabling this filter wouldn’t be a bad idea; it’ll limit the ATS 6.5’s to their most effective range. There’s no point in making a little 6.5-inch speaker flap around below 65 Hz when there’s a monster in the trunk that’s better suited to the task. Passive high pass filters of this type (also known as bass blockers) often do more harm than good due to the fact that the low frequency roll-off is preceded by a substantial peak in response. This unit is quite well behaved and is, thankfully, devoid of that characteristic.
One area in which the ATS 6.5s really excel is the tweeter-mounting department. There are no less than four options when it comes to tweeter installation; angle mount, swivel mount, and two flush mounting options. I found several components in the tweeter installation kit that weren’t even in the manual. If you can’t find a suitable mounting option in this bag of tricks, then you’re not really trying.

Overall, the ATS 6.5’s offer a pretty impressive package. Personally, I’d prefer a bit flatter overall response, but when it comes right down to it, a little installation flexibility goes a long, long way.

Objective
Impedance measurements for this system show a maximum of 21 ohms at 67 Hz and a minimum of 3.5 ohms at 12.9 kHz. Average impedance measured 5.9 ohms between 100 Hz and 20 kHz. One watt at one-meter sensitivity measured 84.7 dB with 200 Hz to 5 kHz band-limited pink noise. RTA measurements show a relatively smooth response that fits with in a window of about 12 dB over the majority of the systems usable range. Semi-anechoic measurements also show a relatively smooth response with the most notable response error consisting of a high frequency rise of about 7 dB centered at about 13 kHz.