need help on transparent sounding 12au7 tubes


I'm currently using NOS RCA clear top 12au7 in my Audio Valve Eklipse preamp. Looking for a 12au7 that's more transparent, detailed, maybe higher resolution to try with this preamp. Not looking for a tubey sound. Thanks.
A true West German Telefunken may be what you are looking for. (Careful as there are many East German Telefunken look a likes). You might try Andy Bouman at Vintage Tube Services. Before I would do that, however, and if you have not already done so, consider carefully cleaning the pins on your RCA's, such that the copper shines. This I find can be rather tedious, but will make for a very audible difference. We tend to be so fastidious about our other connections and this rather important contact is frequently overlooked. Using copper cleaner applied with a Q-tip may help.
I second the Mullard CV4003's. I had a set of these in my Belles preamp and LOVED them. I got mine from Kevin Deal at Upscale Audio.
Believe it or not, the Sino/Chinese are very good and transparent. Unfortunately, they just do not last a long time...... 300 hours of so. They are worth it though.
Quicksilver sells them for about 12-14.00ea. They are graded for low noise.
I would say the Telefunken are most like what you describe followed by Siemens. Andy at VTS is proabably your best source for honestly measured tubes that you can rely on - the guy knows his tubes and seems to be very honest in my experience.
Thanks for all the great recommendation, this is good information to know, will certainly use these recommendation down the line. I plan to clean the pins of the RCA's this weekend, should I use Silclear on it (silver enhancer)?

I just listened to my system tonight (well rested and everything)and it sounds amazing. This is my second night with the Eklipse and I'd have to say I'm very happy. This pre is very quiet, sweet, slightly forward in the midrange which bring out vocals perfectly for rock albums such as Dire Straits Brothers in Arms, SuperTramp, etc.
You can't go wrong with RAM Labs Super Low Noise grade. These are very quiet and transparent and only 2% of tested tubes are graded Super Low Noise. The 12AU7 is difficult to find with low microphonics, especially with NOS tubes. I use Super Low Noise RAM tubes in all of my input and power tubes on my VTL and CAT electronics. Here is the website and I am not affiliated with them other than as a consumer with 30 years in this hobby.
You will have NO problem finding low noise/non-microphonic NOS tubes. You just have to shop with sellers that know how to test for such things. Kevin Deal is one of those that is most fastidious with his testing and grading ( If, by stating, "transparency", you are saying, "no colorations": then you don't want anything British. They will impart an unnatural warmth to your presentation. Siemens and Telefunken are the most transparent, of which the ECC802S would be the ultimate. They were ECC82's, specially selected for low microphonics/noise, linearity, and triode balance(and cost accordingly). There are no new production tubes that can come close to the reproduction accuracy of a properly selected pair of NOS tubes. The exception to that rule in 9 pin miniatures are the EAT tubes ( There again- You WILL pay for the quality. They don't manufacture a 12AU7 unfortunately.
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It's been my experience, over the years, that any equipment with nine pin Mullard or Brimar tubes installed had an added warmth, sugary glaze or "tubey sound"(as the originator of this thread put it) that simply does not exist in live music. Said coloration was easily eliminated when the tubes were replaced with those of German manufacture. What others may prefer/enjoy/seek in their sound does not concern me, as Scar972 asked about "transparent", "detailed" and "resolving" tubes. I replied based on what I know to be true. Scar972- Kevin Deal at Upscale has a great amount of experience with the tubes that he sells, in a wide variety of components. Call, and ask him for suggestions regarding the presentation you'e seeking.
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Tvad, I recently changed rooms to a smaller, nearfield presentation. I had used the Mullard CV 4003 in my PrimaLuna integrated amp and felt the sound was to "warm" in my old room. With the new room set up and the same equipment I tried the Mullards again. Wow, I now know what the hype is all about .
Scar 972- Please let us know what tubes you end up with, and your observations. Tvad- What ever you enjoy is just fine with me(I don't have to listen to it). Rock on!
Thanks to all.
I've read that the RCA clear top I'm using are considered clear and not tubey. Last night, the system sounds amazing, and my initial feeling on this pre may be wrong, I have to listen more to know if I need to change tubes at all.
As I said in my previous post, all these recommendation is great because I will use them in the future, my listening preferences do change from time to time. FIY, just added pics of the new preamp to my page.
The Clear top should be in that "neutral" zone in most applications - and much cheaper than TF or Siemens. Glad it is working for you; you can drive yourself crazy rolling NOS and miss a lot of music while doing so. You might also want to try the RCA Black Plate version, again, much less than the Europeans.
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Tvad, ever compare the RCA 5814 with the 12au7 Blackplates (1954 or thereabouts)?
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I agree with Mofimadness and Tvad. I've tried many different combinations of 12au7s and 12ax7s in the 9 pin sockets of my Air Tight ATM-3 amps. I keep coming back to those airy, easy, musical Mullard cv4003(12au7) boxplates. In conjunction with the transparent sounding Ei Yugo pre-war 12ax7 smooth longplates, (made by the Yugoslavs with the Telefunken equipment and supplies they had puchased from Germany),they provide a wonderful sound synergy. I get essentially the same enjoyable results with the Yugos OR the German made Teles, but the Yugos are considerably less expensive.
RFT from I have had very good luck with the RFT "fats". They are a nice inexpensive alternative. I use a hypex based power amp and the combo of tube with "class d" gives me a sound that is both warm and highly detailed.
Try Sylvania nos marked Baldwin organ from the early sixties, just picked up a pair on ebay for $6.00. I like these better than any other I have tried.
Been through a whole lot of 12AU7's recently on a "quest" of sorts. I finally settled on the RCA triple mica black plate 5814's. They seem to do it all.

The Mullards definitely have an appeal, and do sound different from most other tubes. However there's too much to give up with these to get that seductive midrange. The top and bottom extension just isn't there. They are not neutral sounding. However, as I said, what they do have is very seductive.

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