Hey Jazzdude. Discovering wildcat tubes???? Hmmmmmm . I have been working with vacuum tubes ever since building my first tube gear [dyna pas and mk2 amps kits] in grade 9 electronics class [1967].A little story here..... My first employment in the working world was as a techie for Bell & Howell[Dukane] in their microfilm division.One of our biggest accounts was at the Westinghouse plant in Hamilton Ontario[transformer division]. I will never forget walking into their computer room and seeing a gigantic Univac computer that employed more than 18,000 vacuum tubes! Next to the computer room was a storage facility to house their massive tube inventory.The late Archie MacIssac, who was their Chief electrical engineer at the time,He and I became very close friends. Archie saw the writing on the wall regarding the demise of the vacuum tube from a technical perpective and began collecting tubes. His collection was something to behold, facinating, and enormous! Tubes from all over the Globe, dating back to the earliest stuff, including gigantic watercooled Eimac power triodes and pentodes,some of these tubes are worth a small fortune today.Over the years,I too; became a collector of vacuum tubes and now have a rather humble collection of some very rare tubes .However, most of my collection are limited to audio tubes per sey. I also collect vintage tube gear, but have [reluctantly] sold most of my collection off in recent years, due to space limitations and the mess of stuff that aways seems to accompany these things. However...Sure wish I had kept some of that great old stuff today! If one is to collect vacuum tube gear, one better learn how to repair and retube the stuff.I think its a "given" that the tubes employed in most any circuit designs can make or break the way it will sound in any given system,especially if that given system has the abilty to resolve the amplified imformation.Particularly the vintage stuff,but much of the modern stuff as well. Its really a shame, that todays designers are literally "handcuffed" because of the availabilty and the prohibitive cost of many of these great NOS tubes .Unfortunately, for us anyway, many designers of modern tubed gear have really no choice but to "voice" their creations with todays mediocre sounding modern tubes,their hands are tied!That said.... a lot of the modern stuff[not all] can be transformed into a whole higher order with the great old nos valves. After all,vacuum tube research reached it's pinnicle in the 50's and early 60's.It really shouldn't be much of a surprise, given todays superior passive parts[wire,capacitors,resistors,diodes etc]when designed around good linear transformers, that we are now seeing products coming to the market that are pushing the envelope [sonically speaking]at reasonable cost [in todays dollar]. Relative to the "old guard" well established Corporate American companies .Any one remember the cost of the Marantz 7 or model 5's of the era?Astramonical in todays dollar! There has been an underground movement in DYI vacuum tube audio for many years. In this "imformation age" and the ever growing internet, I am certain we will see many more Supratek-like pruducts reach the masses.A really good thing for the open minded Audiophile. [Audiophile?] geez... I really hate that handle. All the more reason to start collecting those great nos tubes before there ain't any more to be had. Hell...ya need to take out a second mortgage to acquire some of these tubes! We will also see more people designing equipment that will employ "alternative" tube types, due to the cost and availablity of the traditional audio triode tubes used in commercial audio equipment.Interesting, how the industry adopted the 9 pin miniature triodes[12au7,12ax7,12at7 6dj8 et] as the the norm in the amplifiers from the 60's to modern day stuff . Considering the stuff of a decade earlier used their octal based family equivalents . The 6sl7's operating characteristics are basically a cross between a 12ax7 and a 12at7.The nearest 9 pin equivalent would be a 5751.The 6sn7 has the same average plate characteristics as the 12au7 but with a hotter filament.The 6BL7 resembles the 6dj8 miniature triode so common in todays equipment but it has slightly less gain and even lower plate resistance.The basic octal base family of dual triodes evolved from the 30's and 40's and were used mainly in WW2 military communication equipment. The 6sn7 was so highly regarded in private industry that Univac employed them in their computers.Later iterations evolved into the 5691[6sl7]and the 5692[6sn7]Given identical circuit topology,these octals elicit a more linear and focused sound than a 12a?7 or 6dj8,are more extended at the frequency extrememes while also expanding the space and perimeter of the soundfield. Given the demand for these nos tubes,the better ones are now commanding prices approaching that of the premium 12ax7's and 6dj8's so common in modern equipment.The circle will turn again and a new bread will emerge using equivalent alternatives to the 6sn7 and 6sl7 octals. Relatively inexpensive octal triodes from the same era with similar electrical characteristics. Take the 6DN7 and 6EM7 for instance. These are great sounding dual triodes that are dirt cheap from any tube dealer not to mention ham fests and flea markets.We can thank the alternative free thinking pioneers of the industry,men like Scott Franklin and Bruce Moore who introduced the magnificent Luminesence octal based preamp in the early eighties. The Lumi's design topology employed many of these octal based triodes, all hand wired, point to point with discrete circuits and fully regulated vacum tubed power supplies.This preamp was such a radical design change from the accepted norm in the state of the art designs of the day.At the time,the ARC sp-10 and the CJ premiere 3 were considered at the edge of the art and the king of the hill .There is no doubt in my mind,the Lumi was the catalyst and the inspiration to much of the octal based triode tube designs emerging today,.....Supratek included.
