@classic8 they’re off labels such as Siemens and Dario, supposedly made by Amperex in the same factory as the bugle boys according to the vendor. They have shorter plates and are ribbed. That’s about all I could tell you about them.
Primaluna tube rolling 12AU7 Notes
Hi all, I know a lot of people have Primaluna equipment and play around with tubes. I’ve bought a bunch of 12AU7s from Brent Jesse (highly recommended by the way) and thought my notes on the various ones might be interesting or useful to some of you. These notes apply to just the preamp. I have the EVO400 preamp. Tests were changing out just the inboard 4 (out of 6 total) tubes. Amps were Evo300 monoblocks powering Focal Kanta 3 speakers, mostly Cardas wiring throughout.
GE standard tubes (about $30/pr on Brent’s website when on sale). As he says, “good all arounders” which I agree with. Highs are not as airy as other tubes and bass a but less full. Midrange is good. For the money, especially compared to new tubes, I think they are a tremendous deal. I could gladly live with them, but nonetheless they’re at the bottom of the pile here.
RCA cleartops. These are very interesting. They had the most prominent highs of any of the tubes, and some of the best bass. If I had mild/tame speakers and wanted to liven up the system, I would get these. They’re a bit too much with the Focals. They’re not as refined overall as the Europeans but night and day in terms of vividness compared to the GEs. Nice tubes.
Telefunken ribbed plates. Good airy highs, nice midrange. Very refined overall - comparing these to the GE and RCA is like comparing an aged Bordeaux to a new California merlot (what, you say you like scotch? The RCA are a 10 yr old Isla, the GE a Johnnie Walker red, the Telefunken a 18 yr old Macallan). Here we start getting into a more complete, holistic piece of overall sound, with the most realistic presentation in terms of soundstage and detail. This is subtle, but there. The bass is not as full as the RCA or Amperex.
British…unfair perhaps, but I only have two Mullard long plates and two Brimar here compared together. Very nice, midrange-centric. Refined almost as much as the Telefunken but not as much clarity, probably because the highs are not as prominent. Soundstage excellent like the Telefunken. Less bass than the RCA but more than the Telefunken. The midrange can sound very pretty.
Amperex - same factory (Heerlen) as bugle boy according to Brent but off labels. what sticks out here is an all around good tube - midrange close to Brit’s, highs close to Telefunken, bass better than those two. Not quite as complete/refined as the Telefunken in soundstage and overall presentation but close. These are probably my all around favorites.
For those interested in tube rolling, I would recommend it if you have a decently revealing system. That said, the tubes that come with the equipment are good. I like the EL34s in the amps very much, in fact of 5 or so other variants I’ve tried they’re at the top 1 or 2, stock. The PL 12AU7s are ok, not great. I think this is where a good opportunity exists for tube rolling, especially in the preamp. I’ve tried rolling the 12AU7s in the amps and there is some benefit, but perhaps not as big. It can affect the overall palate of the system though, so I’m not discounting it. That is, if a tube has an off flavor to it, it permeates the whole system, so it’s good to get one you enjoy. I’ve had good luck with Radiotechnique and GE military both from Upscale for the amps.
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I post this link pretty frequently, but if you want to know where and when your Phillips tubes were made and what tube type you have, you should learn a little about the manufacturing codes. They are etched into the glass on the side of the tube, usually 2 lines of 3 or 4 letters, numbers or symbols. If you look up the link forget about the drawings showing the "Old Code". I don’t think you’ll find any of those. What you’ll usually see is the first 2 "Examples of correct code format" in the "New Code" drawings. This may seem a little confusing at first, but it’s not that hard to figure out. C:MyFilesWordPerfectPhiltitle.PDF (pocnet.net) If you have any questions, I’ll answer them if I can. |
jimmy2615 Thank you for an excellent report on your findings, I too am one who prefers Amperex for my signal tubes (both 12AU7 and 6DJ8). I was lucky enough to stock up about a decade ago, before tubes skyrocketed in price......I certainly could not afford to buy those tubes at current prices......if I could even find them in stock. I have a bunch of rare tubes, and I use a handful......but I keep most of them in their original boxes. I'll be selling a bunch soon, to buy a nice 300B amp. |
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