Mirage OMD-28 Surround Speaker System Manufacturer Comment
The entire Mirage Loudspeakers team would like to thank Tom Norton and Ultimate A/V magazine for their detailed review of the Mirage flagship OMD system.
We are in total agreement with Mr. Norton's findings, but would like to take this opportunity to comment on a couple of items, particularly the measurement discussion.
All truly full-range loudspeakers like the OMD-28 can be difficult to position in order to achieve smooth low frequency balance in some listening environments. It's simply the nature of the beast. We have found that there is a marked improvement in bass definition and integration when the supplied cone feet are used on carpet or solid flooring surfaces, something Tom states he did not use in the review. This is not to suggest that the bass performance in Tom's room would have been significantly altered with the use of the cones, but we do recommend that customers experiment in their own rooms. One other item that we have found with the OMD-28's is that they tend to work optimally with the speakers spaced further from one another than conventional forward-firing designs.
In terms of the measurements performed by Ultimate A/V, we take some issue with the suggestion that the OMD-28's are "technically inaccurate".
Mr. Norton correctly mentions the difficulty in measuring loudspeakers with unique radiating patterns, such as an Omnipolar system, and then points out deficiencies in the frequency response of the OMD-28. Since the OMD-28 closely mimics an "ideal" omni-directional system in terms of radiation pattern, it does not follow standard "rules" when measured anechoically, and the gated LMS measurement used IS pseudo-anechoic. Judged against the accepted "flat frequency response" goal of a directional forward-radiating system, any Omnipolar design will appear down-tilted and show an apparent "excess of bass". However, any anechoic measurement, by it's very nature, will not take into account the reflected energy that will be present when the loudspeaker is placed in a listening room. An Omnipolar loudspeaker will also not follow the inverse-square law at mid and high frequencies. Both of these facts suggest that an Omnipolar speaker should NOT measure "flat" otherwise it will sound excessively bright and thin in a typical room. In order to correctly assess the performance of the OMD-28's measured performance we rely on the total radiated power response, also known as the "sound power". We would be happy to provide this measurement for your inspection.
Finally, the areas of the frequency response with gross deviations are likely due to the fact that the speaker was measured in-room. No gating will be able to totally window out reflected energy from the room boundaries, particular with an omni-directional radiator.
Again, thank you for a thorough and insightful review!
Senior Acoustic Design Engineer
Mirage Loudspeakers/Audio Products International