Heresy: a non-75 ohm digital cable!
The Mad Scientist is at it again, cooking more interesting non-standard audio accessories in his kitchen. On the menu this time is a digital coaxial cable that is deliberately not 75 ohm and uses carbon fiber as a conductor.
Review samples kindly supplied by Mad Scientist Audio
Retail price: $129
Upgrade RCA plugs: $40 for KLE Copper Harmony or $60 for KLE Silver Harmony, See the manufacturer’s website for more options.
Above: the Heretical won’t stay curled up unless you tie it down. In spite of its buoyancy, however, it is still very flexible.
Normally digital cable makers strive for a cable measuring “75-ohm”, as per the SP/DIF standard. But the Heretical deliberately deviates from this. In fact, the cable has around 37ohms of actual resistance. According to the maker, using carbon fibers as the signal conductor however has some beneficial effects that outweigh the deviation from the 75-ohm characteristic: “The Heretical cable has around 37 ohms of resistance. A reflection that bounces off the DAC’s input socket will travel the length of the cable and back again, thus experiencing around 75 ohms of resistance. As the DAC’s input must be loaded with 75ohms, this causes the reflections to be strongly attenuated. What’s more, reflections will not have the chance to bounce up and down the cable multiple times, as they will be simply turned to heat by the effect of the resistance.” Then the official blurb continues: “Skin Effect is very very small compared to metal conductors. The square waves that make up the digital data are sent at a few megahertz – fairly slow by digital standards. However, the harmonics that make up the square wave go much higher, into the tens or even hundreds of megahertz. At these frequencies, copper has a skin depth of a few micrometers. By comparison, the skin depth for carbon fiber is still as few millimeters. This is important as the correct transmission of all the component harmonics is crucial for the correct transmission of the whole wave. And the higher harmonics are responsible for accurate bit transitions.”
My knowledge of digital theory doesn’t really stretch far enough for me to make sensible comments about the above but to be honest, I don’t really mind. For me, the proof is in the listening. While the standard version of this cable is supplied with modest brass with rhodium plated RCA plugs and very good results are achieved with these according to the maker, my review 1-meter samples were outfitted with the slightly more expensive KLE Innovations Silver Harmony plugs.
The Heretical digital cable’s quality was assessed between an Aurender N10 music server and a Wadia 121 DAC as well as a Wadia 25 DAC. I prepared some cables covering a wide price range to compare with such as a very cheap but pretty good Ceam RG59 (standard coax type), a 70 euro Apogee Wyde Eye and a 600 euro Wireworld Gold Starlight III+. As it turns out, I really needn’t have taken the trouble to take out all these cables and two DACs because the Heretical’s benefits were clearly audible right from the very start.
For the longest time, I have preached asynchronous USB to be a better connection than S/PDIF, but since my experiences with the Jeff Rowland Aeris DAC and the Aurender N10, I’m not so sure anymore that this is a rule set in stone. The interface implementation and the impact of the overall setup and cables used have all proven to be major contributing factors. The Aurender N10 in my opinion is a superb source for all the usual digital formats and so it makes for easy comparisons using either USB or any of its S/PDIF outputs.
All the Aurender’s digital outputs sound very good, but there are still differences that correspond with how I usually experience them. Using standard RG59 cable coaxial sounds fuller in the bottom octaves, but less transparent and less airy than when using an AudioQuest Diamond USB cable (600+ euro). In some situations, the coax sound is not such a bad thing, but it’s definitely a deviation from neutrality. When substituting the RG59 for the more upscale Wyde Eye things only get worse, with woolier bass and softened transients. The Gold Starlight III+ certainly improves on the Wyde Eye by sounding tighter and more solid while retaining the treble fluidity. I really liked the Wireworld a few years ago in a previous setup that was somewhat edgy, but now that my sound is more balanced I think it takes away a little too much reality.
It’s when substituting the Wireworld for the Mad Scientist Heretical that the best balance is achieved: the tightness and speed of USB with airy treble as sweet as the Wireworld’s and with the engaging musical flow of the RG59 cable. There’s a sense of freedom when listening to music using the Heretical that I don’t quite hear when using any of the other digital cables, or USB. Would this be the non-metal nature of the cable? No matter the cause, it’s amusing to note that in spite of its non-75 ohm characteristic, the Heretical sounds as if the clock is pulled from the S/PDIF stream easier than with the other digital cables that I tried.
A final experiment using a Mark Levinson 37 CD transport into any of the two Wadia DACs substantiated my earlier findings, again with the Heretical sounding at once more transparent and better-timed than the Wireworld, while avoiding bass thinness and retaining all the fluidity and air.
If Asynchronous USB is considered the standard, then it should count as a small miracle when a digital coaxial cable sounds more engaging in certain aspects. But let’s leave aside the USB versus SPDIF matter. Judged purely as a digital coaxial cable in comparison to other coaxial digital cables I can be short: the Heretical has taken permanent residence between my CD transport and DAC and is as of now my new reference in digital cables.
The best part? It’s highly affordable, especially if you order one soon.