need help on transparent sounding 12au7 tubes

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 tubemonger.com. 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.

The cleartops are exceptional- something else needs to change in your system.

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.

Bob