SOUND FOR THE NEXT CENTURY

Operational Paths
The LHF^TMSystem
Technical Features
Technical Specs
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BACKGROUND

Extensive literature, written by others, provides the reader with the requirements to meet the 1994/1995 state-of-the-art which LHF tmsurpasses by 20dB, razor sharp accuracy, smooth crystal-clear sound, along with an additional six channels above the new industry standart of "5.1".

While Dolby, DTS and SDDS will compete for market share within the "theatrical" markets for large format cinema and residential media systems, for which the VFS/ LHF tmis ideally suited, additional capabilities were incorporated within the system.

This being a school for multimedia and other presentation applications, such as show control, eight surround channels, incorporating Z axis (height) and periphonic playback capabilities (when installed) will allow full Ambisonics presentation to be played back to the audience.

As installed, discrete operation with a combination of 21 "stereophonic" channels is possible for experimental and development purposes. This theatre is also equipped with a Dolby SEU-4 Studio Surround Sound Encoder Unit.

Sufficient headroom has been engineered into the system to surpass today's 105 dB SPL per channel requirements for wide range digital playback. The system's capabilities extend to 115 dB SPL for live music amplification.

However, analysis by Leader Acoustic Labs indicates that a minimum of 121 dB SPL PK is necessary for live analog amplification of contemporary music to studio quality standards. The VFS/LHF tmsystem meets this requirement for live "CD studio quality" amplification of musicians playing in front of the main L-C-R and sub-woofer system main screen channels. The four channel discrete surround/rear channels bathe the audience in a seamless three-dimensional sound field which elevates live amplified sound performance to a new level of refinement and audience involvement.

Due to our diverse background in studio design, HDTV theatre, cinema systems, computer imaging and presentation techniques our vision and responsibility became translated into this remarkable theatre. In only a few weeks of operation, those who have applied the LHF tmtheatre during the course of their studies, or merely for enjoyment, share the vision. Now this responsibility has been transferred... to those who can feel the difference.

OPERATIONAL PATHS

VFS/LHF tmcontains three systems in one. Active combining electronics engineered by Leader Cinema allow for un-skilled operators to access any of the marvels of LHF tmwithout prior knowledge. VFS/LHF tmcould not stand in the way or eclipse the creativity of the user.

1. Conventional "Dolby" Surround:
Two Dolby (Analog) processors provide decoding of 4-2-4 matrixed source material to the theatre.

• Consumer LHFTMmodified Fosgate M-3A Decoder multiple unbalanced RCA inputs for a "consumer" perspective.
• Dolby SDU-4 Professional studio format Dolby Stereo Decoder with "studio" optimized surround decoding. LHFTMenhancements include sub-woofer combining and processing which the SDU-4 does not offer.

• Left-Centre-Right Screen Channels
• Sub-woofer (channels)
• 2 side channels
• 2 rear channels Dedicated inputs to (future):
• 2 additional screen channels (five in total)
• 4 additional surround/vertical channels

• Dolby SEU4 Surround Encoder

To further enhance the ideal matching between amplifiers and speakers, the amplifiers associated with the main screen channels and sub-woofer system are located in four racks below the screen. This optimizes the power transfer or damping factor, which is required for high-impact sound effects and "concert" performance live music amplification.

The loudspeaker wall (a variation of which may be found in control rooms at major music recording studios worldwide, into which high-quality monitors are also soffit mounted), is padded to reduce reflections from the sound perforated movie screen back to the centre channel speaker mounted behind the screen.

The enormous cavity (720 cu. ft.) created behind the screen, and associated speaker wall also serves as a tuned bass trap to control excessive bass build up in a relatively small, well-damped room.

Unlike a normal cinema, the left and right speakers flank the screen and are "toed in" to form the 60° monitoring position favoured in music tracking studios. Superior imaging and spaciousness between the left and right speaker systems is the result, only achieved with "constant directivity" and phase coherent speaker systems. This provides the user to accurately mix, record and monitor on a large format sound system a luxury unheard of outside only the best world-class studios or film dubbing theatres.

Quite unlike these same studios, this LHF System boasts a Leader D1800 2000 Watt 2 x 18" sub-woofer system tuned to 26 Hz. Weighing in at 480 lbs. and powered with 3000 Watts, the effortless bass warms and soothes the body. During explosive sequences, the "tiger in the tank" is more like "dinosaur breath" in your face while your chair back and seat buckle under other intergalactic effects!

All signals (Left-Centre-Right-Sub) from the projection booth are fed to the screen amplifier racks at +4 dBm, balanced, with a clip level at +28 dBm!

Each amplifier rack is equipped with specialized equalizers (parametric) to optimize each channel to the room and achieve the ISO 2969 cinema response curve. The operator also has the use of three 1/3 octave graphic equalizers to be used as glorified tone controls.

SURROUND SOUND CHANNELS

Apart from a sonically stunning wall of sound from the three front main screen channels and sub woofer, the speakers surrounding the audience again are a proprietary LHFTMdevelopment. The exhilarating experience must be heard and felt to be believed. These LHFTMsurround systems outperform most cinema's main screen channels.

Surround/Ambience Channels

...I feel that the most remarkable aspect of the VFS/LHFTMproject is the integrity of the LHFTMsurround channel. Earlier (October 1994), we had completed a larger theatre (350 seats) at the Judge MacGill Theatre located in the Robson Square Conference Centre. This 35mm motion picture theatre is a state-of-the-art facility for premiere screenings, technical evaluation and VIP screenings of films within the motion picture industry.

This facility was the first theatre internationally to incorporate the LHFTMsurround speaker array. VFS/LHFTMis a logical extension of this technology which provides less than 1.0 dB deviation between seats with low-frequency (power bandwidth) to 32 Hz (in the surround channel).

The results are so stunning, that to ask "how does it sound?" is totally obsolete; "how does it feel?"...or "how large is this space?" are more appropriate. "I'm suspended or lost in outer space" [or words to that effect] have been voiced by audiences at both theatres.

In short, the sonic superiority of the LHFTMmain screen channels and theatre ambience enhancement due to the accuracy of the surround channel sound field, places LHFTMin the elite class of theatre sound. It redefines a cinema experience...truly Ahead-of-the-art!

The acoustical treatment of the room provides the audience with a well-controlled reverberation characteristic of 0.35 seconds. Acoustic treatment follows the "absorption" technique at the front of the room, tapering off to the rear. A diffuse field has been created due to a balcony level with additional seating and multiple 32" TV monitors suspended from five lighting trusses with associated lighting instruments. With an overall ceiling height of 18 feet, raked floor, upholstered theatre seats, and tapered ceiling including treatment low frequencies (and lots of it) are exceptionally well behaved. Not a trace of "boominess" at any level, from a whisper to past eleven! All sound tracks playback with a stunning degree of clarity and smoothness to a full house or an audience of one.

TECHNICAL FEATURES

• DIMENSIONS:
  • Room Volume: 18,500 cu. ft.
  • Rt 60 (Reverberation Time): 0.35 seconds
  • Seats Main Floor: 97
  • Seats Balcony: 13
  • Screen Size: 15 ft. W x 8.5 ft. H
  • Last Row distance to screen: 31 ft. or 3.6H (where H is image height)
  
  
• MAIN SCREEN CHANNELS:
  • 3 x LCS/LHF^TMD1500/9040
  • Max SPL (free space): 129 dB SPL 1 x LCS/LHF TM D1800
  • Sub-Woofer System: Max SPL 27-85 Hz 124 dB SPL
  
  
• SURROUND/REAR CHANNELS:
  • 6 x LCS/LHF^TM1202-5-32SD
  • Max SPL: 32 Hz - 15 KHz 123 dB SPL
  
  
• AMPLIFIER POWER:
  • LCR Main Channels (Woofers): 6 x 15" 3600 Watts RMS
  • HF Drivers: 3 x HF Constant Directivity: 900 Watts RMS
  • LHF^TMD1800 Sub-Woofer System: 3000 Watts RMS
  • Surround Channels: 2 x 600 Watts 1200 Watts RMS
  • Rear Channels: 2 x 300 Watts 600 Watts RMS
  • TOTAL: 9300 Watts RMS
    
    
• LEVELS:
  • Balanced System Max SPL: 119 dB SPL @ Row 5
  • "Controlled" Max SPL: 115 dB SPL @ Row 5
  • All AUX Inputs, Main Inputs and Patching [Balanced XLR]: +4 dB u
    
    
• ELECTRO ACOUSTIC:
  • Main Channels, Seat-to-Seat Deviation: Less than 1.5db
    
  • Typical: +0.3 dB - 0.4 dB
    
  • Worst Seat: -1.5 dB
  • Surround Channels, Seat-to-Seat Deviation: Less than 1.0db (+0.3 to 1.5db)