Why Audio Cables Need Networks

The network is a low-order, phase-correct low-pass filter that effectively rolls off the†ultra high frequency bandwidth of the cable and controls the capacitive and inductive reactance of the cable at lower frequencies. We believe that this approach has provided us with cables that are better suited for transferring audio frequencies — at least this is what our ears have told us.†All cables are filters; i.e., they have inherent LCR (inductance, capacitance, and resistance) characteristics, and their filter characteristics change according to the cable's length and the connecting componentsí impedances. At audio frequencies, uncontrolled filters affect tonal balance and group delay. Transparent's aim is to make audio cable filter behavior more predictable by controlling the cable's filter characteristics with an optimizing filter network.

Transparent's objective is to make sure that cabling has as little impact as possible on the performance potential of the system. This problem is more complex than it appears. Different lengths of cable and different types of cables have different electrical characteristics. These differing electrical characteristics, no matter how small and incidental they may seem, affect the performance of the various components they link. Also, regardless of how short the cables are in a system, they are still the longest signal path in the system. You may have noticed in your experiments with different types of cables that different lengths of the same type of cable sound differently.

These variables cannot be adjusted adequately only through choosing specific cable materials and manipulating geometry. The only predictable and complete way to control these variables is through a properly designed network that has been designed for the specific cable, its length, and its application. In this respect, audio cables are no different than any other audio component. For example, transistors and tubes require networks to work properly in amps, preamps, tuners, and CD players. Speaker drivers require networks to work properly in speakers.

"Cables are important because they are the longest parts of a system and therefore act as efficient antennas that pick up and/or radiate noise." (p.29)

"... One simple, but often overlooked, method of minimizing noise in a system is to limit the system bandwidth to that required by the signal. Use of a circuit bandwidth greater than that required by the signal allows additional noise frequencies to enter the circuit." (p.135)

HENRY W. OTT, Distinguished Member of Technical Staff, AT&T Bell Laboratories (excerpted from Noise Reduction Techniques in Electronic Systems, Second Edition)


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