C Y B E R F i  -  F E A T U R E


By publishing The Genesis Report, QED has returned the Great Cable Debate to its scientific roots. CYBERFi asked a number of leading amplifier manufacturers for their response to the conclusions of QED's investigation. Representatives from Naim, NVA and LFD join cables expert Malcolm Hawksford of Essex University to case a critical eye over the new white paper, assessing its findings in the light of their own research


The report is both right and wrong. In my view high resistance is not the issue. What determines the way that cables affect system performance to a far greater degree is the output impedance of an amplifier. The question of cable inductance, capacitance and resistance has to be considered as an integral part of the amplifier/cable/loudspeaker interfacing equation. Amplifiers such as NVA's, Naim's and Exposure's which do no have a Zobell network on the output, are sensitive to the effects of capacitance and inductance. Transistor amplifiers with Zobell networks or output filtering and valve amplifiers with transformer coupling on their outputs are not so sensitive. If an amplifier has negligible output impedance (ie the damping factor is high), the effect of relatively high cable resistance is minimal. Our LS1 cable is a fairly high resistance cable, but our amplifiers have a 0.0065 ohm output impedance, so there are no ill effects.

Cable directionality is a audible phenomenon. Indeed cable performance can vary with even more obscure factors than this. I have found with solid core cable it is possible to create directionality over a period of time. It's as if the cable beds-in when used aligned one way. If you then reverse one of the cables it can sound worse. But if left, it will bed-in once more over a period of time.

I agree that the cable dielectric is more important than the conductor purity. However if you coat a copper cable in silver, the change will affect performance as much as any change in dielectric material. The dielectric is know to affect cable capacitance more than any other factor with the exception of using Litz construction. Output transformers and Zobell networks hide the deficiencies of cables. So the danger is the wrong cable solution can be prescribed. high capacitance cables apply a cure to the bad audible effects of Zobell networks and output transformers, but as in medicine, it would be much preferable to not have the condition in the first place!

I welcome QED's report. The use of scientific techniques to help evaluate cable is to be applauded. My concern is whether the tests have been carried out in sufficient depth. Individual manufacturers are usually the best source of recommendation for suitable cable to partner their products. Ultimately the big issues concerning cable are the same as those affecting systems. It's all about interfaces from the start of the recording chain to the final link when playing back through a hi-fi system.