This review page is supported in part by the sponsors whose ad banners are displayed below |
|
|
Returning to technical design matters, the use of low source and high load impedances with low cable resistance in-between is the generally accepted method to preserve any hifi signal’s integrity. Unfortunately Don Palmer thinks that this is the worst case for system RF because these conditions generate RF impedance mismatches at both ends of the cable. The resultant RF ringing is spurious noise that will raise the noise floor in the cable to veil and degrade the audio signal.
|
There are many ways to reduce RF noise and ringing in cables. Some methods include impedance matching, ferrite RF absorbers, multiple parallel sections of wire of differing windings and various methods of low-pass filtering. The goal for all these methods is to reduce RF without causing distortion of the audio frequencies. Each method is more or less effective and has its own side effects and sonic character.
Skywire uses electromagnetic shielding with greater RF attenuation than alternative methods. They also think that their side effects are less damaging than most other methods and that their sonic character is superior. It is this combination of greatest reduction of ringing with the least negative side effects that should create an audible sonic improvement. As the maximum magnetic field in the standing wave should, according to Palmer, remain in the center part of the cable coincident with the maximum standing wave currents, Skywire suppresses the circumferential magnetic field at the most critical points of each wire. |
|
|
The shielding material absorbs magnetic waves and is thus more efficient on wave peaks. But Skywire does not focus suppression solely on magnetic standing-wave peaks. Their experience shows that cable sonics are improved with contiguous suppression coils (i.e. no spaces between coil turns). As the total length of suppression coils increases, higher frequency modes get suppressed more completely. Suppressing such modes is like suppressing the higher harmonics of the fundamental ringing with more magnetic wave peaks along the cable.
|
|
Skywire’s cable design uses a patented suppression wire that wraps around each cable. The suppression wire consists of a magnetically permeable core to couple the magnetic wave from the primary (signal conductor) through the magnetic core to a secondary (conductive material around the magnetic core). The conductive secondary is a short circuit which resistively dissipates the voltage generated by the magnetic flux in the core. The core cross-sectional area is so small that it does not couple the audio frequency waves into the secondary. Measurements indicate that it is only effective above one Megahertz. When wound circumferentially around the cable, this material acts like a transformer with a shorted secondary at radio frequencies. This dissipates RF energy as heat and substantially reduces the amplitude of RF ringing in the cable. Skywire’s secondary noise suppression is the use of an electrostatic shield. This shield is terminated to ground on the connector to reduce the amount of airborne noise impinging on the signal conductors.
The primary reduction are the suppression coils whose termination of RF energy is in the short circuit itself. This does not require the coils to be separately terminated to ground to efficiently absorb the electromagnetic energy.
|
|
The actual sonic signature of Skywire Audio cables results from the wire selection, suppression material, length of the suppression coil and the exact placement of the suppression coil around the wire. Increasing the total amount of suppression on the cable determines how well low-level information is revealed. As the length of the suppression material is increased it suppresses higher harmonics of the standing wave modes. A short coil near the middle of the wire will suppress primarily the fundamental mode. As the total coil length increases it will start to suppress the secondary mode, then the tertiary and so on. Each of these has its own sonic signature. The entry-level 1200 Series cables are designed as second-mode cables for a musical midrange balance. The 1400 Series are fourth-mode cables which deliver a smooth midbass through treble range and good top and bottom extension. The top 2020 Series under review is supposed to give a very neutral presentation from top to bottom with the best extension of all. Generally the cables with more suppression will have the lower noise floor which is said to significantly affect their overall presentation.
|
|
Sound. As Skywire’s top cables share the same design from digital to analog interconnects to speaker cable, it was no surprise to find a common sonic signature when each was considered separately. The main features were a very quiet laid-back sound with stunning tonal quality that was even more surprising considering the silver-plated architecture involved. The soundstage was a bit deeper and the separation between each instrument slightly more accurate than with my Naturelle Audio & Legato reference cables. The RF attenuation seemed clearly audible as an avoidance of any excessive treble brightness and a very accurate three-dimensional soundstage. But the most striking achievement was the uncolored and rich midrange not common with silver-plated conductors.
The digital wire in my opinion was the highest achievement at least for my system. The Skywire S/PDIF cable led to very interesting results and gave me the sensation of having a more accurate digital signal with less spurious noise. It didn’t provide further detail but superb noise rejection that led to a quieter background and a more gorgeous ultra-coherent midrange. The treble brightness many digital wires highlight was efficiently reduced. My finding is naturally a function of my personal setup and perhaps my most critical RF ringing issue was located at this particular juncture. On the minus side I gave up a bit of speed and extension at the frequency extremes where the leading edges of transients were a bit softer than with my other digital cables.
|
|
|
|