i just did a review about five different 12ax7a's that might be informative: Amperex Bugle Boy, Mullard short plate, GE short gray plate, Raytheon shiny black plate, Telefunken ribbed plate. i didn't include a Sylvania in the comparison because the only one i have is mostly used up
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Interesting thread. I am currently auditioning a number of 12au7 preamp tubes and was wondering about the scope of the tube industry as it relates to what mfg did and did not do when demand was increased and then, later, when demand dried up. You know, adding features and then reversing course and going back to the basics. Is it accurate that the heyday of tubes was in the late 50's, early 60's? Having an assortment of tubes at my disposal I feel that much of the upgrades tube mfg undertook were in those years, you know, longer plates, getters, black plates vs grey, and other features that were once created to either make the product better or maybe just for marketing purposes only. Sometimes it is hard to tell, but there are subtle differences if you have a resolving system and the only tubes used are the preamp output tubes - and an SS amp. I am not looking for a history lesson (although if there is a book about it, I would read it!) here, but just a synopsis of how those features change the sound and what years you feel are the choice years for tubes. The immediate experience I am having is that the Mullard tubes, despite some added features, such as long plates or red tips, tend to close inward with the added feature sets. Meaning that the midrange is accentuated, but at the expense of the high frequency air that the Amperex tubes provide. Amperex on the other hand, does kind of the opposite, IMHO. Amperex can be thin, Mullard can be thick, and there are many in-between s for each. Any input would be appreciated. I am trying others like RCA, Tung Sol, etc and am fascinated by the sound differences, but as a pragmatist I feel the need for a historical synopsis on the industry so that I can gauge my interest in a certain, hopefully, 10 year period or so of tubes in which to focus on. I assume the best Sylvania tubes came from the early 60's, which may help the OP delineate what years to focus on to ensure best results, regardless if its a preamp tube or an amplifier tube.
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I can see how the Mullard won you over in the 12ax7 tubes. The higher gain provided in those tubes vs the 12au7, is probably a sweet spot. In other words, when I listen to Mullards, the more volume I use the better the sound, which is the opposite of the Amperex. The Amperex are not bright, necessarily, but the top-end shine can be taken that way, especially at higher volumes. While it is an orange (preamp tubes) vs apple (amp tubes) comparison, the attributes of each are still readily apparent. Thanks for posting the video.
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I clicked on the main page, scrolled down, and found this link to a film made in 1958 to promote RCA’s ’Living Stereo’, so serious https://www.audioasylum.com/audio/general/messages/80/806082.html the film, on youtube |
I am almost certain that best Sylvania and RCA are from 1950s, and the earlier the better. At least, that's what I read, I only have 1950s of both. Don't buy RCA from late 1950s, that's, later than 1956, they are a little dark and closed in; early/mid 1950s 12AU7 RCA sound excellent in my VAC, almost as good as Sylvania long black plates from 1950s. |
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