Medium-Mu Twin Triode
Some are labled Hewitt Packard / Amperex. Amperex made them for Packard and put their lable on them.
The Amperex / Hewitt Packard ECC88 / 6DJ8 Vacuum tube is a
miniature type used as a cascade amplifier in VHF color
and black-and-white television tuners.
This tube is also a main stay in pro audio gear
and many high end stereos. It is used especially in
recording studios where perfect sound quality is crucial.
This is one of the best sounding ECC88 / 6DJ8 tubes you
can buy.
It requires a miniature 9-contact socket.
Electrical Data:
Heater Voltage ................................ 6.3 V
Heater Current .............................. 0.365 A
Preferred Substitutes ............... 6ES8 6FW8
Substitutes .............................. 6BK7