Surround Sound Speaker Systems

Emotiva ERT-8.3 Tower Speakers, ERM-6.3 Monitor, and ERD-1 Surround Speakers

On the Bench

I only bench tested the ERT-8.3. Distortion measurements were made within an 80 kHz bandwidth and 1 foot from the respective driver. On the rear panel of the speaker, I set the tweeter to High Extension and Level + 2, the Midrange Level was set at 0, and Boundary Compensation was set to On. These settings gave the flattest response. (See Page 3 for a photo of the rear panel switches.)

Measuring from the lower woofer, at 50 Hz, THD+N was 1.56%.

At 1 kHz, measuring from the lower midrange driver, distortion was 0.68%.

And from the tweeter, at 10 kHz, THD+N was 0.44%. These distortion values represent very good performance.

A graph of THD+N vs. Frequency is shown below. The measurement was taken at 1 foot from the middle of the speaker array. Distortion declines from 10% to 1% between 26 Hz and 65 Hz, and then stays below 1% for the remaining audible band. Again, very nice performance.

Quasi-anechoic frequency response measurements are shown below. The first graph was taken on-axis, and the second at 30⁰ off-axis. The response is reasonably flat from 125 Hz to 20 kHz. There is a hump between 60 Hz and 125 Hz which can easily be flattened with any of the new receivers that have room correction such as Audyssey. Off-axis, the response above 2 kHz begins to roll off slightly, and especially above 16 kHz. Note that the software I am using for these tests is still in its first version, and there is no provision for a microphone compensation file. My calibrated microphone (Earthworks) rolls off 3 dB between 20 kHz and 30 kHz, so the yellow graph line would actually intersect the vertical 31.5 kHz line at a point 3 dB higher than shown in the graphs.

The impdance stays very close to 4 ohms except at 50 Hz. The phase stays within + 20⁰ and - 60⁰, and for most of the audible band, it is within ± 20⁰, so in spite of being a 4 ohm speaker, they should be relatively easy loads for most receivers.