The Tubemonger Library, a great resource for identifying tubes has a couple of pictures of Telefunken 12AU7s labelled Mazda Belvu here:
If yours have the diamond on the bottom and look like the ones in the photos, I'd say they're Telefunkens.
Telefunken in Disguise?
A highly rated Audiogoner sold me what are supposed to be a pair of Telefunken 12au7 smooth plate tubes. What actually arrived were tubes labeled "Mazda BelVu 12au7 ECC82." They do have what appears to be a diamond engraved on bottoms, although it is hard to see. He insists these really are Telefunken - made 12au7 smooth plates. I do not know enough to accept or not. I cannot find anything on-line confirming his representations.
What say the the tube experts?
Neal
What say the the tube experts?
Neal