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Audio Video Article - A Local Revalation

Esoterex Advanced Audio

Esoterex Research ERP7

FOR Clear, clean and utterly neutral sound from this high-tech, innovative digital pre-amplifier.
SUPPLIED BY Esoterex Research.

IT'S GOOD TO SEE AN INCREASING number of worthy, locally designed and produced audio products making their appearance.

 The latest local entrant onto the SA hi-fi scene is Esoterex Research, a company that has come up with a digital pre-amplifier of note. The ERP7 is not only a sonic success, but embraces advanced technology and innovative thinking in an altogether impressive package.

 The motivation behind the Esoterex ERP7 is a perception that the advent of digital sources, and the departure (well, almost) of record decks (which need high-gain phono stages) has created a need for a high-quality, low-gain pre-amp displaying many of the clean, neutral characteristics of passive control modules, but without any of the drawbacks.

An Introduction to Active digital Interconnects

esoterex RESEARCH was the company who conceived the "Active Interconnect" concept. First only for the analog interface between audio components with cable lengths up to 20 meters with no discernible loss of performance. Many of these active cables are now in use for a long time.

Then we turned our attention to the digital domain as far as high end audio is concerned. There we discovered, much to our dismay, the substandard performance of the vast majority of systems investigated. Although the very top end of the market had the correct technology for good digital reproduction.

Some facts about digital signals:

Digital Volume Control

For some time now, audiophiles have been discovering the benefits of passive volume control - dedicated CD based systems not using a pre-amplifier, but rather a simple passive pot to control signal attenuation. This method obviates putting the CD signal through any intervening active circuitry before it enters the power amplifier, resulting in improved:

  • imaging
  • clarity
  • low-level information retention
  • stage width and depth.

Hence the old adage - "NO Preamplifier beats even the best preamplifier."

Hyper Active Interconnects

The Problem

The point of departure for the design of the esoterex RESEARCH Hyper Active Interconnects is the fact that any cable has capacitance which is a function of its physical construction. Even the most expensive Interconnects suffer from the same malady, only to a lesser extent. In the case of an audio cable, this inherent capacitance, in conjunction with the finite and often substantial output impedance of the sound source forms a low pass filter, which attenuates the high frequency components of the signal. 

In addition, most audio sources do not tolerate a capacitive load such as a cable represents. The level of distortion rises disproportional if the load is capactitive. One only has to look at datasheets of typical output drivers. There are of course devices which can drive such loads but the are expensive. In addition to attenuating the signal, phase shifts are introduced. Both, attenuation and phase shifts increase with frequency. Non-linear distortion increases significantly ^t the higher frequencies.