Interconnect construction and performance

Flat interconnects with parallel members typically have the highest propagation speeds and the widest bandwidth with some of them passing signals freely into the gigahertz region. Coaxial interconnects are also relatively high propagation speed, wide bandwidth designs. Flat and coaxial interconnects are the designs of choice for digital and radio frequency transmission. When these extremely wide band interconnects are used for audio applications, however, they are particularly subject to noise infiltration along the entire length of the interconnect, much like an antenna.

The standard ways to approach noise infiltration are through shielding and twisted pair technology, both of which limit interconnect bandwidth to an extent. Good shielding will reduce electrostatic (ES) noise infiltration. A twisted + and - pair will theoretically prevent electromagnetic (EM) noise infiltration by nulling out these noise frequencies. Interconnects that employ these geometries will still pass signals freely into the 100 megaHertz region and beyond, however, which is far more bandwidth than what is required for audio applications

In reality, however, twisted pair technology only goes part of the way toward cancelling out EM noise because the proximity of the twisted + and - pair is never identical over the whole length of the interconnect regardless of how carefully the interconnect is manufactured.

To reduce EM noise beyond what can be achieved through twisted pair technology requires a properly designed network fitted to the specific application and the length and type of interconnect.

Noise infiltration obscures the ability of the interconnect to transfer extremely low level harmonic and spatial information accurately, and it has a tendency to make the system sound brighter and harsher in the high frequency region than what is recorded on the source material. Increased noise floor directly affects our ability to perceive full dynamic range and all its gradations.


The Role of Inductance and Capacitance in Audio Interconnects

Inductance and capacitance need to be carefully controlled in interconnect. Too much or too little of either characteristic will provide undesirable results. Flat interconnects, coaxial interconnects, and twisted pair interconnects exhibit electrical characteristics that are not in the best interest of music for several reasons. In lengths suitable for most home audio systems, these interconnects have too much bandwidth for audio applications and are particularly subject to noise infiltration. Another problem is the point at which these interconnects achieve electrical resonance; i.e., the point at which inductive reactance equals capacitive reactance.But interconnects with extremely wide bandwidth create a thinner and brighter sound than interconnects with less bandwidth.

The Role of Group Delay in Interconnect Design

The propagation speed of frequencies will be delayed to one degree or another in any interconnect. The critical concept regarding propagation speed in interconnects designed for audio applications is that all frequencies should be delayed for the same amount of time (uniform group delay). This means that if different frequencies enter the interconnect at the same time, they should leave the interconnect at the same time.

Wide bandwidth and extremely fast propagation speeds usually go hand in hand. The inductance of interconnects with less bandwidth is usually sufficient to reduce overall propagation speed, but if the interconnects are designed properly, the delay in these interconnects should be uniform over the usable bandwidth of the interconnect.


The Effect of Interconnect Length on Bandwidth and Resonance

An extremely short interconnect will have wider bandwidth than a longer interconnect of the same type because the shorter interconnect will have less inductance and capacitance. Extremely wide bandwidth interconnects are subject to noise infiltration and resonant behavior and sonic byproducts that do not serve music. Extremely short interconnects will sound more alike than they will sound different because of their similar bandwidth and resonant characteristics. In our opinion, they will tend to transfer an audio signal so that it is more like a hi fi experience than it is a musical experience.

Contrary to popular opinion then, shorter is not necessarily better from a musical standpoint. A longer interconnect will tend to sound less bright and fuller because it will have more inductance and hence less bandwidth and a lower resonant point than a shorter interconnect.

The same sonic pitfalls that apply to the "shorter is better" perspective, also apply to "Interconnect Comparator" tests. From an electrical perspective the interconnect comparator behaves like an extremely short piece of interconnect. In other words, the interconnect comparator will have extremely wide bandwidth and will have a relatively high resonant point. A typical interconnect without a network will most closely resemble the electrical characteristics of the interconnect comparator than will a interconnect with a properly designed network. It also follows that the shorter the piece of interconnect, the more it will resemble the sound of the comparator. The basic premise of this comparison is based upon an assumption that a short interconnect is better from a musical performance perspective which as we have discussed earlier, is not the case at least from the point of view of our extensive tests and listening.


The Ideal Interconnect Length for Audio Applications

There is, in fact, an ideal length for any type of interconnect which will establish the proper relationship between capacitance and inductance; i. e., ideal bandwidth and a resonant point that is as low as possible for the application. If this specific "ideal" length of interconnect is compensated properly in its natural roll-off region with a network, it will exhibit very uniform group delay characteristics throughout its entire usable bandwidth; i.e., phase, imaging, timing of harmonics to fundamentals, etc. will be true to the source.

Every THOR Interconnect regardless of length is tuned so that it achieves the same electrical characteristics as an "ideal" length of interconnect for the application, and then it is properly compensated to achieve uniform group delay characteristics.

Because we typically use a variety of different lengths of interconnects in today's complex audio and video systems, our musical interests are better served by choosing interconnects that have all been tuned to achieve the electrical characteristics of an "ideal" length of interconnect.

Strand and Conductor Technology

Conductor material should be pure and consistent, and the conductor surface should be smooth and uniform for best signal transfer. In our opinion, pure silver conductors do not possess inherent qualities that make them a better conductor of music range signals than copper conductors. For audio applications, pure silver will usually require more compensation than many copper conductor configurations, and the cost of pure silver is exorbitant.

The conductors in the THOR Interconnects consist of many strands of single gauge, precision extruded, oxygen free copper. Each strand is annealed to provide an extremely smooth and uniform surface. The strand bundles are precisely wound around a center core of dielectric.

Dielectric Materials

Precision extruded teflon has superior dielectric insulation properties compared to just about any other material except air, but interconnects with sufficient air insulation would be very bulky and difficult to manufacture with consistent results. Teflon works very well on interconnects which require a relatively thin layer to insulate them properly, but teflon insulation would result in a very stiff and difficult to use speaker interconnect.

Interconnect Geometry

As discussed earlier, twisted pair technology results in superior audio range performance because of the nulling effect of + and - conductor proximity. Many audio interconnects provide twisted pair technology. The precision and consistency of the twists are very important to achieving as much nulling as possible and to insure that any two sections of interconnect of the same length will exhibit the same relationship of inductance to capacitance. The interconnect jacket must be tightly and precision extruded around the twisted pair to hold the twisted pair firmly in place. The tight jacket insures that interconnects will maintain their intended electrical characteristics even when the interconnect is flexed or bent as in home audio installations.

THOR speaker Interconnects consist of strands of copper that are precision machine wound to our exact specifications. Interconnect jackets are pressure extruded to hold conductors firmly in place when the interconnect is bent or twisted. THOR Interconnects have amazingly consistent electrical characteristics from sample to sample. They also exhibit rock solid electrical characteristics when they are bent or twisted. These manufacturing techniques allow us to fit every performance level and length of THOR Interconnect with precision.

Soldering Techniques

We do not use solder pots or extremely hot soldering irons to construct THOR Interconnect. We carefully temper the strands in each conductor with heat controlled soldering irons, and we use only enough heat to flow high purity silver solder.