TECH2

Measurements

Frequency response

144 Hz to 20 kHz ±16.0 dB, ±5.1 dB to 10 kHz (on-axis)
144 Hz to 20 kHz ±14.4 dB, ±4.9 dB to 10 kHz (averaged)

Bass limit

160 Hz at 86.8 dB

MCMäxx™ output

95 dB at 1 meter

I originally thought it would be most appropriate to measure the Eco Terra in its intended use environment: the swimming pool. However, I encountered numerous problems that prevented me from getting a useful measurement underwater. Most notably, my Clio FW audio analyzer refused to work while submerged. Usually, if I have a problem with my measurement gear it’s because I forgot to wear my lab coat, but even that drastic step couldn’t get everything working. Measurement gear can be so finicky.

Reduced to measuring the Eco Terra in the same old boring way I measure everything else, I placed it atop a 2-meter stand and placed the measurement microphone at a distance of 1 meter from the left speaker, enough to incorporate the diffraction effects of the enclosure. I connected my measurement gear through the Eco Terra’s line input, and used the AC power supply. The quasi-anechoic measurement method I used removes the effects of reflections from nearby objects, simulating measurements in an anechoic chamber. I placed 2 feet of attic insulation on the ground between the Eco Terra and the mike to kill the ground reflection and reduce the minimum measurement frequency. To get the bass response, I close-miked the left driver, scaled the response appropriately, then spliced the result to the average of quasi-anechoic measurements taken at 0°, ±10°, ±20°, and ±30°. (You can also see the on-axis result in the graph). I used the Clio in MLS mode for the quasi-anechoic measurements and log chirp mode for the close-miked measurement.

The Eco Terra may be just a glorified, waterproof boombox, but even given its limitations, it’s a pretty lo-fi device. There’s no bass response to speak of below about 150 Hz, and no significant treble response above about 12 kHz. However, that’s not such a bad thing, because from a psychoacoustic standpoint, the reduced treble balances out the reduced bass. If the Eco Terra had flat response to 20 kHz, it’d probably sound bright.

From 400 Hz to 4 kHz, the Eco Terra’s frequency response is surprisingly smooth, although biased toward the treble. There’s a pretty big peak at 8 kHz, although it’s high enough in frequency that it probably won’t be all that distracting to many listeners. Off-axis response is very consistent with the on-axis response, as you can see in the graph, where the on-axis and the response averaged across a ±30° window are almost identical.

Bass output measurements were performed using CEA-2010 technique at 2 meters, then scaled them up +6 dB per CEA-2010 requirements to give an equivalent of a 1-meter measurement. Both channels were fed the test tones through the line input.

When people say X audio product “doesn’t have any bass,” they’re almost always exaggerating, but when I say the Eco Terra doesn’t have any bass, it really doesn’t have any. The lowest frequency at which I was able to get a bass output measurement was 160 Hz. (The next lowest test tone is at 125 Hz.) I got 86.8 dB at 160 Hz, which isn’t much even for a speaker dock. These measurements were done with the AC power supply; measurements made using the batteries were about the same.

Fortunately, full-band output is pretty good. Using my ultra-exclusive, semi-scientific MCMäxx™ test — playing Mötley Crüe’s “Kickstart My Heart” and cranking up the volume until it becomes too distorted or harsh, then reducing the volume one notch and measuring the output level at 1 meter — I got a result of 95 dB, loud enough to fill a decent-sized room or pool area with sound, although not loud enough that anyone will want to dance. — Brent Butterworth

Bottom Line

I find the Eco Terra highly amusing, and worth the $150 just for the novelty factor. A floating boombox? Music underwater? Awesome. As long as that’s your mind set, it’s a cool product. If you’re expecting serious sound or need serious volume, you’re going to be disappointed. It’s just a rugged, floating, waterproof (OK, resistant), way to bring some music to the water, and under it.