@samzx12 ,
ECC82 /12AU7 Mullard longplates, square getter, 1950s vintage, Great Britain.
Found on Brent Jessee site...
These are all the older long narrow plate version, with the rare early
SQUARE top getter, with the 1950s date code. These are incredible
tubes with a fine soundstage, clean top end with a touch of midrange
warmth. Rare.
The different types of Mullards and year produced results in different sonic signatures. CV491 military and CV4003 are warm, textured, and laid-back. The ECC82 square getter is a more open tube, so is the ECC82/12AU7 Mullard longplates, halo getter.
Mullard reissues have nothing in common sonically with NOS Mullards. The Mullard name and trademark have been acquired by the New Sensor Corporation (Russian factory); same comany that makes new Tung-Sol, Sovtek, Electro-Harmonix.
(I have never tried Cifties).