Why Audio Cables Need Networks? An official Transparent Audio explanation…
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.
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)
Cable without a properly designed network acts like an antenna and readily picks up noise from the numerous electronic sources that are so much a part of our everyday lives. This antenna effect interferes with the ability of cable to transfer the relatively low frequencies (20 Hz-20 Khz) required of an audio signal. Noise interferes with a cable's ability to transfer an audio signal with the richness, smoothness, and naturalness of music. Noisy cables tend to sound thin, bright, and electronic. Therefore, to reduce the impact of unwanted signals, Transparent believes that it is important to limit the bandwidth of the cable to an amount ideal for the intended application.
The differences between a cable with and without a network can easily be shown on a network analyzer. With an impedance of 10 ohms at the source, a Transparent interconnect with a network starts to roll off ultra high frequencies slowly and evenly starting at approximately 1.3 MHz. Transparent's network eliminates troublesome noise without affecting the ability of the cable to transfer all the fundamental and harmonic frequencies humans can sense. A typical cable without a network shows unlimited bandwidth. Non-network cables act like a wide-open conduit for unwanted frequencies in audio applications.
Transparent's networks are also designed to help the cable transfer mid and lower audio frequencies more efficiently. Cables without networks tend to become more capacitive at mid to low frequencies, thereby resisting these frequencies. Cables without networks at typical lengths found in audio systems can not physically possess an ideal amount of inductance to pass mid to low frequencies with the same efficiency as they pass high frequencies. Cables without networks pass harmonic information more efficiently than they do fundamental frequencies which affects our impression of the tonal balance of the system. Without the proper balance of fundamentals, a system will tend to sound more mechanical and electronic. Transparent's networks maintain a more ideal balance of capacitive and inductive reactance by adding just the right amount of inductance to the network for each cable design given its length. Transparent Network Technology insures that your components will be able to provide the rich, smooth, and musical sound that they were designed to deliver. The mechanical and electronic presence of reproduced music fades into the background, making the music more emotionally accessible to the listener.
In addition to adding just the right amount of inductance, Transparent meticulously controls the ultra high frequency roll-off behavior of the cable. Achieving optimal roll-off behavior results in more natural harmonic extension and decay. This most time-consuming aspect of the design process consists of many cycles of triangulation: measurements of the output impedance characteristics of the cable's targeted source components (in the case of Reference and OPUS Series cables, a specific component), correlating these measurements with the Transparent design model to determine an appropriate range of network values, and long term listening with the targeted source components in the Transparent Music and Film Studios to refine and finally to verify network values.
The end result is an audio cable design that will perform as intended for its application just like any other well designed audio component.