Empirical Audio

About Empirical Audio

What makes an excellent Speaker Cable?

Speaker cables transfer high-bandwidth power in a low-impedance environment. The power amplifier output impedance is usually on the order of a few tenths of an ohm and the speaker load typically varies from 3-30 ohms depending on the signal frequency, particular speaker and crossover. Transient currents of 30 amps or more can occur during dynamic, high-level music passages when driving low-efficiency speakers. Because power transfer is the primary purpose of a speaker cable, resistance and inductance are more important than capacitance. The low output impedance of the power amplifier is generally capable of driving relatively high capacitance, whereas significant voltage drops can develop across the speaker cable and connectors due to resistance and inductance, particularly when high-current transients occur. Extremely high capacitance has been known to cause instability in some amplifiers, but this is not typical.

Minimize Resistance

Empirical Audio speaker cables minimize resistance by using a sufficient number of parallel runs of wire to equal the equivalent of 11 gauge. We have determined empirically that a minimum of 11 gauge is required to work effectively with a broad range of amplifiers and speakers. We do not offer a cost-reduced version of this for more efficient or low-budget systems, because it will invariably be installed in low efficiency systems, resulting in voltage drops and an audible loss of dynamics. We also offer only spade lug terminations on our speaker cables. We have determined empirically that banana plugs sound fine in the most efficient systems, but the vast majority of high-end resolving systems are less efficient, so voltage drops will occur across banana plugs causing a loss in dynamics. This is why we do NOT offer banana plugs on our cables.

Minimize Inductance

Empirical Audio speaker cables minimize inductance by grouping the conductors as multiple twisted-pairs. The pairs are connected so that the current in first conductor of each pair runs in the opposite direction from the current in the second conductor. The magnetic field coupling between the twisted-pairs reduces the inductance, making it lower than the self-inductance of the wires themselves. Most other cable manufacturers use large gauge conductors to make the self-inductance as low as possible, but they do not take advantage of the magnetic field coupling that can actually make the inductance even lower. Some other manufacturers actually run parallel small gauge wires for each of the two conductors, but this actually increases inductance, so it is a bad idea.

Minimize Skin-effect

Skin-effect occurs when the high-frequency currents flow on the outer "skin" of the conductors whereas lower frequencies have more uniform current distribution across the conductor cross-section. This happens when too large a gauge is chosen for the conductors. The effect is that the impedance (primarily inductance and capacitance) is different for low frequencies than high frequencies. This difference in impedance can cause phase shifts in high-frequency passages relative to low-frequency passages, causing a smearing effect to the music. If a sufficiently small gauge is chosen for the conductors, all frequencies are "forced" to flow more uniformly in the conductors.

Empirical Audio minimizes skin effect by careful choice of conductor size to optimize for low as well as high frequencies. This insures that the current distribution is relatively uniform at all audio frequencies.

Minimize multiple-conductor interaction

Multiple conductors are required to minimize inductance and minimize skin effect, but if the geometry is not carefully designed, crosstalk between these can negate many of the positive effects. Empirical Audio designs virtually eliminate interactions between twisted pairs.

Minimize Dielectric Absorption and Dissipation Factor

Placing each twisted-pair in a separate tube forces air dielectric around the pairs, which helps to lower the effective dielectric constant. A lower dielectric constant is desirable because it results in lower dielectric absorption and lower dissipation factor.

Other Technical Papers

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