Made in USA.
At first glance, it seemed to be Tung-Sol round place. Construction is very similar to the round place with black glass but it has diamond shape top mica, dual copper grid posts.
It looks very unusual. Supper sounding same or better round base version.
Tested matched and very high as new. One maeked Tung-Sol and other marked RCA
Made in W.Germany by Valvo.
Gold pins version, Closed getter. Very rare today. Super balanced sounding.
Nos in original box. Matched pair are available.
Made in Hamburg - W.Germany by Valvo.
Gold pins, Pinched Waist and O-Getter with double support. One of the earliest 12AT7 in the world was introduced by Valvo. One of three highest grade 12AT7s (GEC A2900, Valvo 6021 Pinched Waist and Telefinken ECC801S). Great bass control and sweet midrange, very musical. Long life tube. Nos in box. Matched pair are available.
The lable marked VALVO but same as SIEMENS E82CC (Triple Mica).
Made in W.Germany by Siemens & Halske. Very balanced and detailed sounding.
One of the great version from Siemens.
Nos in original box.
Made in G.Britain by Mullard (1950s).
Clear glass, Brown base, Bottom D-Getter. Can bring to you the superb sound. Nearly same as 6SN7s family and can be replace for them BUT can be not used for replacing where the plate volate over 300V.
Nos in original box.