When installing a home theatre system, the proper set up for the sound system ensures the highest quality results. The ideal position for the main speaker is behind the screen on the same level as the right and left speakers. This maintains:
- Quality sound localization for the dialogues and overall sound effects
- Movie Theatre quality that is true to the original sound mixing engineerin
- The ability to use identical speakers due to space restrictions and avoids interference with other objects on the floor or ceiling.
Figures 1 & 2 and Table 1 show the third-octave band insertion loss results in detail from 100 through 20,000 Hz. and summarizes the average and maximum screen insertion loss (IL) for each screen sample, as well as the band in which the maximum IL occurred. These results are valid for third-octave bands between 100 and 20,000 Hz.
Acoustically Transparent AT1200/AT Grey Test Procedure
Testing of the AT1200/AT Grey acoustically transparent material was performed by engineers at Auralex Acoustics in Indianapolis, IN in November of 2005. A Klipsch loudspeaker was positioned in a semi-anechoic test room such that it simulated a center-channel configuration in a typical theater setup. An Earthworks omni-directional microphone was placed 24″ from the loudspeaker. Wideband (20-20,000 Hz) pink noise was played through the loudspeaker using the Goldline Audio Toolkit DVD. The third-octave band levels were measured with the TerraSonde Audio Toolbox 3 analyzer using Real-Time Analysis (RTA) module.1 The overall noise level was set such that the signal-to-noise in the test room was at least 25 dB in all bands of concern. A 30-second average of the sound level was measured and saved with no screen sample in place.
Using the temporary screen framing apparatus provided by Draper, the screen samples were placed between the loudspeaker and the microphone. The wideband pink noise signal was played again through the loudspeaker and the third-octave band levels were measured and saved for each screen sample. Nominal screen sample size was 64″ wide by 36″ high. The distance from microphone to screen sample surface was ~18″. (Note: Different screen-to-loudspeaker and/or screen-to-microphone distances yielded no significant changes in the measured results.)
1 Microphone and analyzer were calibrated to 94 dB(SPL) at 1 kHz. Levels were measured from 25-20,000 Hz, but only the bands of concern for transmissibility are reported, i.e., 100-20,000 Hz.
Photo 1: Special lighting effects show the silhouette of the front and center channel speakers hidden behind the AT Grey projection screen.
Photo 2: Draper 119″ HDTV Onyx with AT Grey viewing surface and a Vel-Tex® covered frame. Photography: ©Scott Arthur, Weaverville, NC. Design/Installation: Scott Varn, Harmony Interiors, Asheville, NC.
About Draper Acoustically Transparent AT1200 & AT Grey
Draper’s acoustically transparent (AT) viewing surface is the most innovative and versatile acoustically transparent front projection screen material available. With virtually no loss of sound quality, it allows a center channel speaker to be positioned directly behind the screen, the optimal location for full range audio performance. With over 76,000 microscopic openings per square foot, both the AT1200 and AT Grey have the sound transmission characteristics of high quality speaker grille cloth, with less than 6% light loss. Both of Draper’s acoustically transparent screen materials allow audio and video to interact seamlessly, creating the ultimate home theatre experience.