TMH Qualified And WHISE Launch Into Homes

TMH Corporation, Los Angeles, California and WHISE, Melbourne, Australia, announce the first product to meet the standards of TMH Qualified, the WHISE model EMW624. TMH Qualified sets a new standard for the highest level of performance for equipment and methods meant to optimize both professional and home installations of audio and video systems. TMH Qualified combines years of research into the fundamentals of music and sound reproduction for the home and similar sized professional sites with extensive, properly conducted listening tests to set a higher level of quality than ever before available.The first product to become TMH Qualified is a subwoofer design, because, as Tomlinson Holman, President of TMH puts it, ""this is probably the most important contribution to the loudspeaker design since the 1970s, the era that Neville Thiele and Richard Small were adding so much to the design lexicon. Interestingly, like Thiele and Smallís work, this new development also comes from Australian electrical engineers, Graeme Huon and Greg Cambrell. The extension to earlier work represented in the new subwoofer involves changing from one electrical engineering view of the world, the lumped parameter model, to a more sophisticated view, widely recognized in electrical engineering for its contributions, the distributed parameter model. This is a little hard to describe in simple terms because it is so different, but the design method owes more to advanced electrical engineering theory than conventional loudspeaker design. What is being done might be best described as Parametric Acoustic Modelingô.The completely new design method simultaneously optimizes all of the following: frequency and phase response, distortion, headroom, sensitivity, the acoustic load on the cone of the driver and the electrical load it presents to amplifiers. The design is based on a new theory of how to optimize loudspeaker drivers and their enclosures, which has already been the subject of patent applications worldwide and technical papers given at AES meetings. For the first time in any low-frequency loudspeaker, the group delay is practically zero, that is, the phase response corresponds to a constant delay time vs. frequency. Laurie Rincham noted the importance of this in his 1985 AES paper, ""The Subjective Importance Of Uniform Group Delay At Low Frequencies.""""We found this device while searching the world for a better approach to what has long been a problem. Our search was for our first TMH Qualified Room customer, Post Logic, in Los Angeles. There, high-definition telecine specialist Lou Levinson works every day to produce the very best transfers from film to the new medium, and he sought audio ëbeyond the state of the artí because he recognizes the value of great audio to the overall presentation of a film transfer,"" said Holman. ""The WHISE subwoofer significantly outperformed any older technology, and both measurements and blind listening test agreed on this.""One basic problem for the subwoofer in 5.1-channel audio is that it must reproduce all of the lowest frequency content. Since it comes after bass management, the subwoofer carries the load of all five channels added together, plus the Low Frequency Effects channel (the 0.1 channel) at ten deciBels over the capability of any one main channel. Whereas a film sound system must play cleanly to 103 dB SPL in the midrange, once all the signals are added together, the subwoofer must play up to a maximum level of 121 dB, which no practical home subwoofer or set of subwoofers has ever done, until now.Here is how the requirement is calculated.SPL = 20log[10L1/20 + 10L2/20 + 10L3/20 + 10L4/20 + 10L5/20 + 10L6/20], where L1 through L6 are the maximum required levels in each of the channels. Adding together 5 channels at 103 dB and one at 113 dB results in a requirement for 121 dB requirement. To understand the difference between the requirement for 103 dB and 121 dB, understand that a subwoofer with a sensitivity of 90 dB/m/w requires only 20 watts to reach 103 dB, but 1,250 watts to reach 121 dB. Fortunately, the high sensitivity of the EMW624 at 94 dB/m/w requires a power amplifier rated at 300 watts to reach 121 dB, a much more practical value. Although at first glance 121 dB sounds awfully loud, in fact at 31.5 Hz it is about equivalent to 100 dB SPL in the mid-range, a loud but quite tolerable level. This occurs due to the Fletcher-Munson effect, wherein low frequencies require a higher level to sound equally loud as the mid-range.""Coming up with new methods of evaluation of subwoofers was the key to our involvement with new designs,"" says Holman. ""We developed custom test signals that stretch the limits of the envelope, although they turn out to be analytical signals much like certain sounds that we hear in movies and, occasionally at least, in music. Our boinker test signal is an optimum test since it combines a narrow frequency so distortion is readily evident, with a high peak level, which actually occurs in real program material. This sounds complicated perhaps, but in fact using the test couldnít be simpler"" just play it at a standardized level and listen."" The tests are available on TMH licensed test discs from The Hollywood Edge. In addition to new forms of testing TMH Qualified products undergo a battery of more conventional tests, as well as extensive listening tests, to ensure that each model TMH Qualified represents a true contribution to a new state of the art.The technology was on display at the January Consumer Electronics Show in Las Vegas, in the Alexis Park Resort Room 2763. Editor Gary Reber and Widescreen Review reviewer Les Linton both experienced the presentation, which utilized a special 10.2 channel loudspeaker configuration. Other than three front full range channels and two side full range channels plus subwoofers the other speaker locations were somewhat mysterious, the speakers did sound to be placed high toward the ceiling with the subwoofers on the floor. In one 6.0 performance recorded by DMPís Tom Jung, a height loudspeaker was used. Gary Reber: ""The presentation reproduced both specially recorded music material in 10 channel discrete plus other 5.1 music material. There was no video. Three listeners sat in a triangular arrangement with our heads leaned toward the ""sweet spot,"" in a completely dark ""blacked-out"" small room. I have never experienced a more holosonic three-dimensional soundfield. Bass extension was extremely deep and powerful yet always natural sounding. Clarity throughout the full frequency range was exemplary, as was dynamic capability. Imaging was lifelike, creating a sense of realism rarely, if ever experienced in recordings. The whole experience was a dream come true for me. This, I thought, is what surround sound is all about. I congratulate Tomlinson Holman and Australian electrical engineers, Graeme Huon and Greg Cambrell for an exceptional achievement in sonic realism."" The following White Paper is provided by TMH Corporation. For more information contact Fitz Koenig, 213 742 0030, (fkoenig@tmhlabs.com)