The Next Generation... Independent Analysis of TDS╥ The Audio Bug, Incorporated The following are results of comprehensive, independent testing of the TDS« Passive Harmonic Enhancement (H.E.) Technology which were conducted in January 1999 utilizing TEF 20 analysis. The tests were performed by Don Washburn of The Audio Bug, Incorporated. Mr. Washburn has been measuring audio products and acoustical events for over twenty years and is one of the founding members of the TEF Advisory Board. Extensive testing of this Technology, both objective and subjective, have confirmed that it does indeed provide an input signal dependent, time-related enhancement whose effect varies with the level and frequency content of the program material. The TDS« H.E. is achieved primarily as the result of the extension of harmonics present in the original program. The transformers designed for the TDS Passive H.E. products provide a voltage gain whose increased level, coupled with the TDS "spectral decay" effect, produces a greatly enhanced signal. There is also a definite TDS frequency response curve which occurs as a result of the transformers coupling. Taken together, the audible results are quite pleasing. A wide variety of tests were conducted during the evaluation. First, we examined the change in level resulting from the TDS H.E. process engaged compared to the bypassed mode. We used Noise Level Analysis and pink noise, simulating music program, and found that the device causes an increase in level. A precision attenuator, with steps of 1 dB, was used to adjust levels so that the non-engaged mode and engaged modes were normalized. This level compensation allowed a direct comparison of the signal with and without TDS H.E. without level variation. Next, the TDS H.E. unit's frequency response was documented with real-time analysis. One-third octave plots were made of TDS bypassed, engaged and then engaged with levels compensated. Response variations resulting from the TDS process were readily apparent. The effects of the TDS H.E. are probably best illustrated using three-dimensional displays called "waterfalls." The TEF 20 analyzer employs a process called Maximum Length Sequence, or MLS, to perform this test. The MLS test signal presents an excellent alternative to complex waveforms such as speech and music in a calibrated, repeatable form. The resulting measurements accurately represent the dynamic process inherent in the TDS H.E. Technology.
Finally, acoustical response analysis was performed
using a reference quality sound reproduction system consisting of high quality, full audio
range loudspeakers driven by reference quality electronics. The purpose of this test was
to analyze the harmonic response of the system and compare it to results obtained when
using TDS H.E. Technology on the system. The reference audio system was first calibrated.
The measurement in Figure 5 The frequency spectrum displayed is 12Hz - 24,000Hz; the time in milliseconds (16.646 ms) is the time period of decay analyzed and the amplitude in decibels (dB) is the energy of those frequency components. A 30 dB range is shown. Note the regions of the graph that are devoid of information.
Listening tests with the TDS H.E. system is a unique experience. The process has a very definite, positive effect. The most immediately apparent effect of TDS H.E. is increased output level. Yet, even when levels are normalized between the bypassed and engaged conditions, the harmonic enhancement is still quite evident. As demonstrated with our objective tests and confirmed with our subjective or listening tests, TDS H.E. enhances virtually any type of program material, yielding a fresh perspective to recordings by offering much improved detail, depth and a broadened sound stage. We believe the reasons for the natural qualities inherent in the TDS H.E. Technology lie in the fact that the TDS H.E. process is a dynamic response to a signal which is already present; the input source. Also, since the process operates across the entire frequency spectrum, there are no annoying "peaks" generated, as one might find when employing an equalizer. Based on our test results, it is our opinion that the claims made by True Dimensional Sound, Inc. regarding the manner with which the TDS Passive H.E. Technology operates as well as it's resulting enhancement to an audio signal, are verified. The Audio Bug, Incorporated
Mr. Washburn has published a number of technical papers, conducted numerous training seminars, addressed a number of organizations including the Audio Engineering Society and the National Systems Contractors Association and is a member of the TEF Advisory Board and is a certified TEF instructor. Employing the industry’s most sophisticated measurement equipment, he provides objective, state-of-the-art product evaluations, computer-assisted system designs and acoustical services to manufacturers and industry users. About The Equipment Used: TEF 20 is the industry’s most sophisticated measurement equipment and is designed to perform Time, Energy and Frequency (TEF) measurements using the science of Time Delay Spectrometry. The power of the TEF 20 platform lies in its ability to join specialized software and the TEF analyzer with a computer to form a complete measurement system. TEF 20 features a powerful DSP device with the speed and power to execute millions of instructions per second enabling it to accurately process complex acoustical data, making it the most accurate and state-of-the-art technology available with which to analyze acoustical phenomena. |
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Figure 6
