Cable Topologies

Difference between interconnects (generally) and (specifically) Atlas.

In a simple physics experiment at school you are given a battery, a light bulb and two pieces of wire and asked to make a lighting circuit. You connect one wire to the positive terminal of the battery and then to the positive terminal of the light bulb, you connect the second wire to the base (negative) of the bulb. When you complete the circuit by attaching the cable to the negative terminal of the battery the circuit is complete and the bulb lights – bravo!

In this respect most circuits work the same, a positive (or signal) conductor carries the current to the load and the negative ( return) conductor completes the circuit. Hifi interconnect cables work exactly the same way, we have a signal conductor which carries the delicate hifi signal from the source ( streamer, CD, pre amplifier etc) to the destination ( pre amplifier, power amplifier etc) and a return conductor which completes the circuit.

As all audio cables transfer musical information between source and destination then the audio quality is affected considerably by the topology and material used in this process. Listed below are various interconnect topologies listed in a hierarchical fashion to help try and demystify the jargon often associated with the selection of hifi cables.

Coaxial.

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A coaxial cable has a single central signal conductor (stranded or solid) which transfers the delicate signal between source and destination, surrounded by a metallic shield which is used as a “return” conductor. This unbalanced return whilst providing some form of shield for stray electric fields does not provide any protection from induced magnetic fields.

This cable topology is popular for many reasons;

  • Only a single high quality conductor (stranded or solid) needs to be used for the signal conductor.
  • A cheaper material can be used for the screen (return)
  • When connected between a pre amplifier and a source component the return conductor is connected to the preamplifier 0v and usually then later to ground.
  • As its a coaxial cable it can be designed to have a specific characteristic impedance and in some circumstances can be used for both analogue and digital use ( two for one:))
  • The screening effect of the cable are compromised as signal return currents may also circulate in the screen material.
  • These cables are non directional by manufacture and can be plugged in any way straight from the box.

Symmetrical (or dual core) cable.

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This type of cable again uses a high quality conductor to handle the signal transfer but uses an identical conductor (return) to compete the circuit. These cables most often deliver better audio fidelity than a coaxial cable. These twisted pair designs provides greater immunity to magnetic fields but without a shield are still susceptible to Electrical interference.

  • They present an equal impedance on both circuit paths which is good practice
  • The electrical characteristics of both conductors are identical which delivers consistent results
  • When connected to a preamplifier the return conductor is connected to the system 0v and mostly later to the system ground.
  • They however have double the volume of the important signal conductor ( so they are often at least twice as expensive.
  • They have no shielding and rely on twisting as simple protection.
  • These products are non directional by manufacture and can be plugged any way around straight from the box.

Pseudo balanced (symmetrical plus screen).

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This topology improves on the fundamental strengths of the symmetrical cable above but adds an improved screening component to the cable. Twin identical conductors are enclosed within a high quality shield, however in Atlas pseudo balanced cables one additional step is taken. The shield is connected ( via our dual drain connection) to the return conductor at one end only.

This provides an independent screen to minimise and control electro magnetic fields, EMI and RFI which is a major source of fidelity compromise these days.

  • These cables deliver improved performance over the preview two topologies.
  • The return conductor is connected to the system 0v and then mostly to ground
  • This topology offers good screening performance as the screen whilst connected to the system 0v has no circulating signal components within (as it is only connected at one end of the cable).
  • These cables are directional by manufacture and perform best when the “source” end ( end where the screen is connected to the return conductor) is connected to the audio preamplifier ( generally it’s near the input connectors on an analogue preamplifier where the 0v and ground are connected).

Pseudo balanced with independent ground (Grun).

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The pseudo balanced cable topology although offering great performance has one small but in Hifi terms large flaw and that is that the screen when connected to system 0v can be modulated by any circulating currents that exist within the product. In an ideal electrical environment all ground references should be at the same “potential” as not to generate any circulating currents. So the natural extension to the pseudo balanced cable is the “symmetrical with independent ground” topology.

This involves connecting the cable screen to system ground externally via an independent grounding cable (grun) and directly to your home ground point (earth). The results are simply outstanding, with no circulating current in the screens and no modulation of the 0v at the screen connection point ( in a pseudo balanced cable) the true capability of the interconnect can be heard and crucially demonstrated.

  • The screen is connected directly to ground and not system 0v.
  • The true benefit of the conductor material and dielectric can be delivered.
  • The true constancy of crimping as opposed to soldering can be delivered.
  • These cables are non directional by manufacture and can initially be connected any way around straight from the box.

Atlas Grun technology.

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Using Atlas Grun cables and adapters the optimum fidelity can be achieved from compliant cables (Asimi and Mavros).

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Various options exist to either connect these cables as pseudo-balanced or “symmetrical with Independent earth”.

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