Anyone ever have, use or hear this tube?

@thecarpathian -

I had a set that I used in a 12AU7/12AX7 Cayin integrated amp. They were very quiet, and warmly-revealing tubes. Mine did not last 40,000+ hours, but I'm not complaining. And yes, they are black-shielded.

@wharfy ,

Yes, I forgot to mention they are coated with a black rfi/emi shielding.

They were made I think for a single specific company. If you did any tube rolling in the Cayin, how did they compare to other, less expensive tubes? Thanks!

@thecarpathian

I did a fair amount of tube rolling, with both the AU7 and AX7. I started with new production EH 12AU7-they are ok, are dependable, and very quiet. The Genalex ECC82 is terrific for modern production tubes--good dynamics, resolution across the sound spectrum, are rugged, and again no microphonics. Tung-Sol 12AU7/6189 sounds terrific and have low microphonics. If you find NOS Mullard 12AU7 you will get a tube with the Mullard house sound--great creamy mids, a tad rolled-off at the higher ends. The new Mullard 12AU7 are Russian production and are detailed, low distortion and terrific for their price. FWIW, my F-I-L also had sets of G73R because he was an electrical engineer for Hewlett-Packard, back in the day. That’s how I acquired them.

Before selling the Cayin (which was paired with a 2005-era Jolida JD100 CD player-GE5751’s sound GREAT in it), I started rolling 12AU7 variants because my father-in-law was a ham radio enthusiast, and had a cabinet full. The Sylvania 6189W is a AU7 variant and I liked it very much--clear resolution, good top and bottom end. Raytheon 5814 is good, for the same reasons as the Sylvania 6189W. The AU7 variant I liked the most is the CBS/Hytron 5814a. It is detailed with great dynamics and low distortion. Ironically, with the rolling I did I did’t try the Amperex 7316.

Since the G73R are Telefunken’s, from experience I think Telefunken made awesome signal tubes across the board. As time has passed, they have gotten expensive. Sure enough, I looked up the pricing and Tube Depot listed them at $500 a piece.

Hope this is helpful!

What audio equipment do you have that has 12AU7s?

David

Thanks, David.

I have about 14 pair of 12au7 variants. CBS /Hytron one of my favorites.

Mullard CV4003 is another good one. Telefunken red tips labeled for Tektronix equipment, Westinghouse 337 a surprisingly good tube if you can find them, Amperex, Amperex 7316 with ’D’ getter (my favorite), regular Telefunken long and short plates, Cifte, RCA black plates...can’t remember the rest.

The G73R’s would go in a Simply Italy integrated I’m contemplating buying. Last gear I had that the 12au7’s went in was an Odyssey Audio Candela preamp. Gone for a few years now. They're all just sitting in my safe, for lack of a better place to store them.