Just pulled my RCA Blackplates and put in the SIEMENS CV491-12AU7-ECC802/S-K1007 you lent me. Right off the bat struck by an impressive open "air" at the top end. The soundstage is large even with solo piano. The midrange seems ruler flat, and the bass is tight and accurate. Of course I'm listening to Beethoven's 4th and 5th Concertos over and over, and Mussorgsky - Pictures at an Exhibition
Original Version & Orchestration by Vladimir Ashkenazy with Vladimir Ashkenazy playing solo on Piano.
Kind of seems I'm playing music the Siemens would hit out of the park. We'll see how they compare to the blackplates when I roll up to some jazz CDs, and the new Kings of Leon should be a good test as well.
How do I go about identifying which company manufactured the 12au7 tube. I have couple of Baldwin 12au7 Black Plates with the following code p280/59-21. The person that I purchased it from said they were Raytheon. Is there a decoder ring that I need to obtain to identify
TIA