![]() The device consists of an dual wound toroidal transformer providing 2x15Vac. The I元00 is an opto-coupler that has an additional feedback photodiode that allows a sample of the internal LED flux to be measured and used to compensate for the non linear characteristics if the opto-coupler. I started looking at alternate ways to electrically isolate line level audio signals, and I came across the I元00 by Vishay. I wanted to avoid using transformers to achieve a more flat frequency response. The normal solution to eliminating hum if the earthing cannot be arrange in a suitable way would be to place audio isolating transformers in the line level signals. Normally an audio system will be set up in such a way that all earthing comes back to a common star point. Because powered speakers can be plugged into any electrical outlets in the house, it is not possible to know the layout of the earthing system to ensure that mains hum is not introduced. How simple is that! Listen and enjoy.I had built a set of powered speakers but I was having problems with mains hum and noise. So there is one problem, the dispersion of light across time ? and two avenues towards a better result: less dispersion in the fiber (better polymers and ultimately quartz), and less dispersion by filtering the input angle. ![]() Less light gets through a multi-fiber cable, but the light that does get into the fibers comes out within in a much smaller time-envelope. This narrow-aperture effect is similar to how a pin-hole camera can take a picture without a lens ? by letting in light at only a very limited range of angles, a picture can be taken, whereas removing the lens from a wider aperture would make photography impossible. Because each fiber is limited as to what angle of input can enter the fiber, there is far less variety, and far less dispersion over time. The almost complete solution to this problem is to use hundreds of much smaller fibers in a 1.0mm bundle. Even if the fiber were absolutely perfect, the signal would be spread across time because light rays entering at different angles take different length paths and arrives with different amounts of delay. The fiber is a relatively huge 1.0mm in diameter, and the LED light source is also relatively large, spraying light into the fiber at many different angles. ![]() There is another serious dispersal mechanism in the Toslink system. The punch line: The less dispersion in the fiber, the less distortion in the final analog audio signal presented to our ears. The inability to decode shows first at higher frequencies (not audio frequencies, this is a mono stream of digital audio information), so reduced bandwidth is a measurable signature of light being dispersed by a fiber. This delayed part of the signal prevents the computer charged with decoding this information from being able to decode properly, or even at all. The problem is that the dispersed light does get through the cable, but only after it has taken a longer path, like a pool ball bouncing off the side-rails, causing it to arrive later. This can be measured as a loss of amplitude ? but amplitude is not the problem, a 50% true loss would have no effect on sound quality. Even if the LED light source in a Toslink system were coherent, the light entering a fiber-optic cable is scattered and dispersed by imperfections and impurities in the fiber. If the light source were a coherent laser, firing into a vacuum, all the light would stay straight, arriving at its destination at the same time. When the question is ?how can a fiber-optic cable change the sound? the answer is easier to explain than for almost any other type of cable. All models and all lengths are now available Toslink to Toslink and Toslink to 3.5mm Mini Optical. And now, the 3.5mm Mini Optical connector, also somewhat incorrectly known as Mini-Toslink, is everywhere ? from the 3.5mm dual-purpose headphone jack on a Mac laptop, to inputs on some of the finest portables.įor these many reasons, AudioQuest has refined and renewed our line of serious high performance OptiLink cables. While, thanks to HDMI, Toslink is not so often used to connect a DVD player to an A/V receiver, Toslink connectors are common on cable-boxes, TV sets, subwoofers, all sorts of products. S/P-DIF is transmitted through Digital Coax and Toslink fiber optics (EIA-J), making them still some of the most important cables in electronic entertainment. The S/P-DIF (Sony? Philips Digital InterFace), which arrived in 1983 along with the CD, is still very much a part of our world today. However, these current generation digital technologies are only part of the story, just as the challenge of designing, manufacturing and choosing the best analog interconnects and speaker cables is as important as ever. ![]() The audio frontier is all abuzz these days with the pleasure possible though HDMI, USB, FireWire? and Ethernet connections.
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