Everyone knows that maintaining a 75 Ohm characteristic impedance is critical for digital cables, in order to ensure that their digital components are performing at their best. This is what we call "common knowledge" and even neophyte audiophiles are intimately familiar with it.
This was not always "common knowledge" - and it took an interesting project launched in 1992 to establish the importance of a standard that was always there to begin with. Here's that story, in a nutshell:
Back in the early days of audiophile digimania, the CD format offered "Perfect Sound Forever" ... CD players were selling like hotcakes, and the general public was fairly happy with trading their records for these new, shiny discs.
Audiophiles, however, weren't exactly as welcoming. The performance of CD was considered to be unworthy of the "High End" label, with only a few exceptions, so - as things generally tend to happen in audiophilia - some very bright folks took the existing technology and made it better. In this case, what they did was split the CD player into two separate boxes for its two separate functions:
The first box ("Transport") would spin the disc and pull the data off of it, and assemble the data and timing codes into an amalgamated bi-phase signal known as a "Manchester Code." Contrary to rumor and superstition, this actually is an AC signal - an "analog" signal, if you will - made up of square waves comprised of fairly high fundamental frequencies and really, really high harmonics.
The second box ("Digital to Analog Converter" or "DAC") would receive that analog AC Manchester code and decode it into the music is supposedly represented.
All that was needed was a special cable to connect these two boxes together in order to get the data from the first box to the second box. This signaled the birth of the DIGITAL CABLE as a category, but it happens to have actually taken a little while before the sensitivities of the interface were understood.
It wasn't so long before the market was saturated with "digital" cables, most of which were simply a single analog interconnect torn away from an ordinary analog interconnect pair, and then labeled "digital" for the purpose. There was no attention really paid to the need for a digital cable to hold an impedance characteristic constant over its length, and so there existed at the time a population of "digital" cables in the market that affected the performance of their Transport:DAC combinations in different ways, and yet none of them were truly appropriate (or predictable).
1991 comes along, and the difference between digital cables is demonstrated to one young and incredulous 24 year old Floridian audiophile: Chris Sommovigo. A dealer had lent him a new kind of digital cable in the hope that Chris might discover how much better it was than the ordinary one he was using between his Luxman transport and Audio Alchemy DDE. Chris (having been trained in the fine art of BS detection) was convinced that it couldn't possibly make a difference. "Bits are Bits" went the maxim and he had bought into that notion without reserve or remorse.
That is, of course, until the new cable was installed. It had affected the sound in a serious way. It was actually quite BAD. Terrible. The music sounded flat, dynamically anemic, washed out.
Chris sought the help of a local microwave engineer friend of his, one John Bauer, who proceeded to teach him about the importance of matching the impedance characteristic of the cable to the impedance of the load. He learned about "reflections," and studied up on Voltage Standing Wave Ratios and signal velocities. He was given a 1957 Radio Amateur's Handbook as a source rich with information, and had an expert in microwave transmission to learn from.
It wasn't too long before Chris and John designed the very first, truly authentic and precise 75 Ohm digital cable for the audiophile. They chose to use "semirigid" microwave cable because of its extreme precision to great bandwidths, and its ultra-low leakage characteristics. If they could make a cable that could ensure the proper signal environment for digital transfer between components, they would have a really viable product and improve the state of reproduced sound throughout the galaxy!
There was a snag: All transports and DACs had their digital ports as RCA connectors, which are not 75 Ohm connectors. Combining industry-standard RCA plugs onto the cables in order to mate with these jacks would only compromise things even more. So they set about designing a connector that would mate to the RCA jack, but that would hold a 75 Ohm impedance precisely up until the point it connects to the chassis of the component. In this way, at the very least, impedance would be preserved for every millimeter it remained in the cable.
A few prototypes were assembled and tested. Finally, fireworks went off in the sky, the angels sang in choruses of Hallelujah!, and the concept was proven to their satisfaction quite easily. There was much celebrating and drinking of single-malt scotch. There may also have been a few cigars ... they were in South Florida, after all.
And so, in 1992, ILLUMINATI Electronic Systems and Cables was launched, and the new "Datastream Reference" digital cable was born and released into the world with not very much fanfare or attention. It was easily the most difficult cable to use, being made essentially of a unforgivingly inflexible copper tubing-based coaxial cable the likes of which could have been used for tactical combat purposes in the right hands.
The Datastream Reference was promoted with a direct mail brochure that looked so amateurish, it should have scared off anyone who received it in the mail. As a matter of fact, it DID scare them off. Thousands of brochures were mailed to prospective clients, culled from the mailing list of Stereophile's subscriber base, with an offer for the world's most precise 75 Ohm Digital Cable (replete with rather strange looking RCA connectors), for a mere and modest $75.00.
Chris had actually stuffed the brochures into the envelopes on his parents' kitchen table, one by one, with the help of his tireless and doting grandmother, Nancy. Together they managed to stuff, seal, stamp, and mail 6,000 or so brochures. And those were in the days when both the envelopes AND the stamps had to be moistened!
Of the 6,000 offers that were released into the wild, only 25 of them came back with a check. 25. That's roughly a smidgen more than 0.4% for you math-whizzes.
Disappointed but not discouraged, they trod on like good soldiers, and the DataStream Reference was the beneficiary of some incredible word of mouth. Before too long ILLUMINATI Electronic Systems and Cables had about 20 retail dealers and several hundred very happy clients - all now very much aware of how important the 75 Ohm Characteristic truly is for these sensitive digital interfaces.
Little by little Illuminati's reputation grew, gaining the attention of audiophiles around the world, until such time as it became established as the de-facto standard of digital cables and signal cable brands. The story Illuminati told about the importance of the 75 Ohm impedance managed to resonate with everyone who proved it to themselves by trying an Illuminati cable. And even though Chris sold the Intellectual Property for all of the existing Illuminati designs to Kimber Kable back in 1997 and closed the Illuminati shop forever after just 5 years in the market, the brand ILLUMINATI still has meaning to those who will recall the contribution those early cables made to the scene, and how Illuminati established the performance standard.
And while it is possible that you may have known prior to ILLUMINATI's category-defining digital cable that maintaining an appropriate impedance characteristic over a very wide (GHz) band is critical to the overall performance of a front end of digital separates - it is also quite likely that you know about the 75 Ohm issue because an idealistic 25 year old cable designer from Miami pitched a little stink about it back in 1992 with a digital cable that established the pass/fail line for every digital cable that came after it.
While many analog cable designs are also attributable to the rather peculiar design talents of Chris Sommovigo, more salient to this story are the digital cables he designed for the industry, including (but not limited to) the following:
- Illuminati DataStream Reference
- Illuminati DataFlex Reference
- Kimber DX-50
- Kimber D-60
- Kimber D-75
- Kimber DV-30
- Kimber Orchid
- i2 Digital X-60
- Stereovox HDXV
- Stereovox XV2
- Stereolab XV-Ultra
- Stereolab TRØN