Why Essential Sound Products Power Cords Make A Difference - Proven Technology & Validated Build Quality!

"With 'miles' of cable and wire between the power station and the ac mains outlet, how can a 6-foot power cord make a difference?"  ESP customer
To answer this question let's look at the 'big picture'.

Electric power travels from the power station through high-voltage transmission lines. The idea behind high-voltage transmission is minimal energy loss and current flow. A single transmission line typically carries enough power for multiple homes, and can be thought of as an "energy resevoir". Outside our homes and businesses a "step down" transformer converts the energy conduction to low-voltage, high-current wiring, which is relatively "lossy" or inefficient. Low resistance materials like copper wire are used to minimize energy loss.

Electrical codes in North America define 14-gauge copper as the smallest wire size used for ac mains service. So, why do most audio components come with an 18-gauge power cord? The "stock" power cord creates a "bottle neck" restricting current flow.

You're probably aware that the ac mains voltage carrier frequency is 60Hz (North America).

The common assumption is that current flows to our appliances continuously at the same frequency as the voltage - like the example of power to simple resistive device like a light bulb. For simple electric devices, any power cord that has the appropriate amperage rating will do.

For most appliances including our audio/video electronic components, current supply is a little more complicated...

Audio components have complex power supplies that perform several functions including rectifying "ac" to "dc", stepping down the voltage, and storing energy for use as demanded.

For most of the carrier frequency cycle no current actually flows to the component, as it is powered by the stored energy in the power supply. Current flow is "switched" on/off, flowing in "pulses" every half-cycle of the ac mains carrier frequency. Power supply inductance causes a delay or negative phase shift between voltage and current. Current draw is mainly to refill the suply capacitors.

If the current pulse were a continuous sine wave, its frequency would be significantly higher than the ac mains carrier frequency.

Current pulse amplitude increases with increasing demand. The oscilloscope screen image shows 4-seconds of music being amplified. What is revealing is how closely this modulation follows the musical signal being processed and how dynamic are the instantaneous current changes. To the extent that current flow modulations are restricted or delayed, the power supply cannot meet demand to accurately process the musical signal. Therefore, not only is flow capacity important, "response time" and "bandwidth" of the power cord matters!

This distortion is not comprehended by current performance metrics. However, it is clearly audible and is characterized by dynamic compression, harsh midrange and treble transients, and lack of bass extension.

Now that we understand how audio component power demands can change dramatically, closely following the waveform of the musical signal being processed, and that current flow occurs during a very limited portion of the cycle, it's obvious why the "stock" 18-gauge power cord is a "bottle neck". The gauge needs to be larger so that the cord has more flow capacity, comparable to the ac mains wiring. We'll just use a 14-gauge power cord to better match the ac mains wiring - right? NOT!

Larger gauge conductors introduce phase distortions - time delays between lower and higher frequencies. The effect is blurred imaging, bloated, sluggish bass response and high frequency roll-off. 18-gauge conductors have higher bandwidth and phase performance; 20-gauge conductors, are even better with no phase distortions until 27kHz, well beyond the audible range.

Design features, audio component power cord:
1. Larger Effective Gauge - comparable size
    to ac mains wiring.
2. Smaller Gauge Conductors - better response
    time and phase performance.
3. Shielding - every other type of audio cable
    is shielded, why not a power cord?

The illustration shows a section of our patented power cable design. Multiple 20-gauge line and neutral conductors are used in a dual-quad parallel array. These smaller conductors have significantly faster response time than a single large conductor. They filter the current to maintain proper phase performance. Combined, they have the current capacity of a much larger conductor. The maximum-coverage braided copper shield effectively rejects RFI and EMI. The shield also contains the strong magnetic field that surrounds the power cable to prevent hum noises in signal-carrying cables.

Impedance is the equivalent of resistance in an alternating current (ac) and varies with frequency. The 18-gauge power cord has significantly higher impedance than the other cords. A stock 14-gauge cord has approx. 60% lower impedance at 120Hz than the 18-gauge cord. MusicCord, which is 16-gauge equivalent has comparable impedance to the stock 14-gauge cord. MusicCord-PRO has roughly half the impedance of the 14-gauge cord and only about 1/5 the impedance of the stock 18-gauge cord.

Since the power cord is in series with the component power supply, lower cable impedance lowers overall ESR (Equivalent Series Resistance). Lower ESR means less voltage drop and less transformer hysteresis. Lower ESR results in more resolution, and faster capacitor charge/discharge. In summary, the power supply operates more efficiently and is more responsive. Dynamic contrasts are greater and transients are cleaner.

With the attention paid to the elimination of noise in professional and high-fidelity audio, and the prevalence of shielded microphone and interconnect cables, one would expect that shielded power cords would be standard in the audio industry. Like other cables, power cords can pick up RFI (Radio Frequency Interference). Moreover, power cords are a known source of EMI (Electro-Magnetic Interference) as the strong magnetic field that surrounds the power cable can cause hum in signal cables.

Comparing an unshielded "stock" power cord to a shielded MusicCord-PRO in a THD+N test on a D/A converter, the shielded MusicCord-PRO affords approx. -6dB broadband lower noise floor!

Our shielded power cords are particularly effective in avoiding hum issues in venues with fluorescent lighting!

"More Than A Conqueror" audio samples made by playing the same mix through an Allen & Heath Mixwizard console. This sample was made with the stock power cord used with the console.

The image is a waveform analysis using Samplitude Pro X "spectorgram" where the energy at various frequencies is indicated by color and intensity. Pay special attention to the spectrogram close-up surrounded by the red square. Visual comparison to the same area on the proceeding slide (same audio sample with MusicCord-PRO used on the Allen & Heath console) is evidence that the recording has been affected.