The CV3884 (commercially the ECC40) has two independent triodes within the single envelope and with a gain of 30 would be useful for most purposes including instrumentation. Mullard describe the ECC40 as a low-microphony double triode with separate cathodes, primarily intended for use as an AF voltage amplifier or phase splitter. The 6SN7GT was the valve it was designed to replace and three years later it was superseded by the ECC82 on the B9A base.
The groove around the hard glass foot where it joins to the soft glass envelope looks typical Philips Eindhoven. The type face is spartan plate gothic as used on Mullard valves.
Face view of one stitched anode. Note the heat radiating fin above the control grid supports.
The Mullard logo. On the skirt sized lower portion of the envelope is the pip to orientate the valve correctly in the socket. This is the final iteration in the development of the B8A base. Originally a metal skirt with spigot was employed as can be seen in UU9.
Side view of the twin triode sections.
The thin glass tube envelope is 20 mm in diameter and, excluding the B8A base pins, is 61 mm tall.
