Surround Sound Speaker Systems
- Written by Jim Clements
- Published on 07 May 2009
- Emotiva ERT-8.3 Tower Speakers, ERM-6.3 Monitor, and ERD-1 Surround Speakers
- Page 2: Design of the Emotiva Speakers
- Page 3: Setup of the Emotiva Speakers
- Page 4: The Emotiva Speakers In Use
- Page 5: The Emotiva ERT-8.3 Tower Speakers On the Bench
- Page 6: Conclusions About the Emotiva Speakers
- All Pages
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 withinÂ Â± 200, so in spite of being a 4 ohm speaker, they should be relatively easy loads for most receivers.