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If anybody out there remembers, or even cares for that matter, I had been trying out several 12AX7/5751 tube replacements for my new Jolida JD-1701 tube/mosfet hybrid integrated, and have posted some impressions of the tubes as I have tried them. The Jolida hybrid's operate with a pair of 12AX7's in circuit via the preamp section, and come stock with Chinese 12AX7's. As Joe S. once said (of a different tube), I wasn't "getting any shin burns from my sox rolling up and down in excitement" with these Chinese tubes so I set out on a journey to find replacements. He he he, laugh every time I read that.Speaking of Joe S., I wanted to thank him for posting all of his impressions of all those tubes he has tried, it's a nice "guide" to NOS tubes for newbie's (like I was) or for anyone for that matter. What's more, in almost spine tingling similarity, my impressions of the tubes I have tried have almost exactly matched the impressions Joe S. has noted of the exact same tubes. The tubes I have tried so far, from worst to best (hint, hint) are: Chinese 12AX7-->Sovtek 12AX7LPS--> Raytheon 5751--> Amperex 12AX7--> Sylvania 5751
After purchasing and then hearing the Amperex "Orange Map" series 12AX7's in my system, I thought for sure this was THE tube for me. Two days later I happened to stumble upon a brand new, never used pair of Sylvania 5751 Black Plates from 1957 at a local electronic surplus store for a fraction of the cost of the Amperex's. The Sylvania's are just a beautiful tube, triple mica spacers, very rigid and beautifully braced plates and getters.
This is getting too long, on to the impressions. At first I loved the Amperex tubes, which were much warmer than the Sovtek's I was using, much more focused and had a much bigger and wider soundstage. The Amperex's are very rich and thick, smooth and more refined but still very detailed. Their low noise and warm tone seems to give way to a jet black background. How was the "fuzz" that Joe S. has described typically found in 12AX7 tubes? Well, to me "realizing" this "fuzz" was something I eventually learned and realized after I tried the Raytheon's. I then understood what the 12AX7 "fuzz" was after hearing the ultra focused, ultra clean sounding Raytheon's. In case for some reason some of you have forgotten my comments, god for bid, I didn't like the Raytheon's only because they lacked a bit of life and were too laid back in my system. The Amperex tubes seemed to have displayed little or no fuzz at all, or so it seemed for the time being. Over all when comparing the Amperex tubes to lesser 12AX7's you get much more focus, much more depth to the soundstage, more warmth and refinement and there's less fuzz and less of that sense that images are overblown.
The Sylvania's. In short, the Sylvania's quickly knocked the Amperex's out of circuit about as fast as George Costanza came running from the bathroom yelling "Say Vandelay!...Say Vandelay!" This tube is just beautiful. Just as Joe S. had found, the midrange is simply glorious, it's wide open and seemingly completely free of any veils whatsoever. This gives way to a very 3-D like central image where vocals and acoustic instruments are to die for (It's to "die" for Joe). Moreover, just as Joe also found the soundstage and the images within it take on more of a 3-D feel, which makes for a very involving and thrilling sound. This tube is also very resolute and can bring out subtle, micro level information. Again Joe S. had found, this tube can be slightly forward in balance in presentation, to which I concur but would not say that the tube is bright, or "hot" in any way. It's warm, refined and controlled, just slightly forward where it places images and how far they are into the room. In my system it's about perfect and works quite well with my speakers. How's the fuzz? Gone. There's a complete lack of fuzz which lends to clearly defined images and a more focused, proportional and realistic soundstage. Overall it's very lively, resolute and refined.
As I switched back and forth between the two tubes it had become clearer to me that the Amperex tubes still suffered from that 12AX7 fuzz, but again much less than inferior 12AX7's. Some people may find this "fuzz" or "misty" character of 12AX7's pleasing or dazzling, but ultimately it's unrealistic and fatiguing. Sometimes a saxaphone could sound quite big and dazzling or lively at times with the Amperex tubes, but it was overblown in proportion and lacked resolution to image outlines. The Sylvania's display focus, define image outlines and maintain proportion all the while displaying life and air. Oh and the bass? Both tubes display excellent bass- extended, tight and articulate. The Sylvania's may have the upper hand here with slightly more rhythmic bass.
And so the Sylvania's are the declared winners. Well if you made it this far through my warbled mess of impressionistic garble, I commend you. I've found THE tube for my system and hope to keep it in circuit for a long time (yeah right). If you can get your hands on a pair of these beauties I highly recommend them.
Sean Heisler
I agree with the description of the Sylvania 5751 Gold black plate. This tube is simply a gem - it sounds suave, liquid, very refined and utterly musical and yet it is very lively, produces high density solid 3D images and have very good pace and rhyhtm. These qualities rarely come together! It massacred the GE 5751. The GE 5751 black plate sounds somewhere in between the Sylvania Gold and the standard GE 5751 tho, and that is still a good thing.
Yes, the Sylvania's are quite nice, and are just as you described. I'd love to try a standard or black plate GE 5751, there's more of them around and I'd like to know they could be a good alternative as NOS tubes slowly dwindle in supply.Sean
Hi,I have some Sylvania 5751's, and was wondering if these are the "gold label" that you speak of. These have gold printing, and say JHS 5751, made in USA, and underneath that...Sylvania. They are blackplate with three mica spacers, and have a rectangler round wire getter just above the last mica spacer. I have been using the Raytheon 5751 blackplates with the "windmill" getter up to this point, but will give these a try this weekend.
TIA
John
Those are the Sylvania's I was talking about. I have the "CAA Government Conract" Sylvania 5751's. Sylvania sold the exact same tube under different "labels", one for the standard market and the other labeled and packaged for government contract channels. Here's how Joe S. describes it:"These are early Sylvania 5751s from the '50s and they are distinguished from their later brethren by their black plates. The Gold Brand (literally, Sylvania's premium consumer tube line) version is a bit unusual in that the black plate gold brands had steel pins rather than the gold pins of other tubes in that line. Both of these tubes were apparently made on the same production line - those intended for the consumer market got the Gold Brand label and those for government contract were custom labeled for the acquiring agency (JHS or CAA for example - CAA-5751, JHS-5751). The ink used on the tubes themselves was gold and it rubs off easily, so even NOS tubes can have partial labels. Now all of this is my conjecture based on comparing the internal structures carefully and comparative listening - but after doing so I am convinced the tubes are identical."
Try them out and please let me or us know how you like them!
Sean Heisler
It pays to swap, or at least try some other tubes.:-)
Jack
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