Perreaux Prisma 350 7Maximising System Potential, Interconnects and Speaker Cables Bi-amping

7Maximising System Potential

Interconnects

and Speaker

Cables

Bi-amping

Balanced Interconnects

An often-ignored area in high fidelity systems is the cabling connecting the various components. Interconnect leads should be high quality cable with substantial terminations. Gold plate is inherently resistant to corrosion, and an excellent conductor. The presence of corrosion induces distortion and poor conductivity will seriously interfere with sound quality. Terminations must plug snugly into sockets to maintain maximum conductivity and to avoid annoying earthing problems.

Speaker cabling is equally critical. Use only solidly constructed cable of high purity copper or silver content. Again, gold plated terminations are recommended, of the spade or banana plug type. Use cables of equal length and as short as possible to maintain uniform electrical resistance at the lowest possible level. If your amplifier is closer to one of your speakers than the other, avoid coiling the longer lead as this can create inductance, with the potential of reduced high frequency performance. Keep all connections clean, firm and tight. The traditional adage that a chain is only as strong as its weakest link most certainly applies to audio systems.

Bi-amping uses two similarly powered amplifiers, with exactly the same input sensitivity so that, when the same input signal is provided to each of them, the output level will be exactly the same. This can often be done with one power amplifier connected to the tweeters and another to the woofers, as it spreads the power requirement between the two amplifiers. Bi-amping can achieve greater control, dynamics and resolution than if you try to run everything from a single stereo amplifier.

The use of the balanced signal inputs and outputs can have the effect of cleaning up hums, buzzes, radio frequency interference (RFI) and general extraneous rubbish that can enter an audio system. A balanced signal input system operates on the principle of differential amplification. The positive and negative inputs are contrasted against one another and the difference between them is amplified. Noise entering the system is imposed equally on the positive and negative signals and therefore will not be amplified, as no differential voltage exists.

The term used to describe the quality of the effect is called Common Mode Rejection Ratio (CMRR). CMRR is an equipment and system specification, which describes how well unwanted common mode signals are counteracted when used in conjunction with balanced connections. CMRR action prevents the egress and build up of extraneous hum; buzzes and RFI when analogue signals are conveyed down cables and between equipment powered from different locations and is widely used in professional audio applications.

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