The E813CC is a modern implementation of the Mullard classic ECC83.
The company (Blackburn Microtech Solutions) was the last part of the old Mullard factory complex and had been de-merged from the parent Philips company. The company made specialist cathode assemblies for CRT production. Most of the output went to a Philips CRT production facility in the far east. As flat screen televisions and computer monitors replaced CRT's the company made losses and was forced to close. The small production of audio valves also ceased.
The E813CC is essentially a planar construction triode but for audio the disc seal construction was not required. A CRT style cathode has a fine wire grid rather than the hole found in CRT production. The anode disc is held at a distance above the grid. This layout confines the electrons to a narrow beam and should be less prone to distortion than the conventional ECC83 construction.
The envelope has printed lettering vertical alone the envelope. One side is the type designation and the other is the company name.
The electrodes in close-up. The heater and cathode is contained within the bell that has the grid covering the hole in the top. The grid bell has side struts that form part of the anode support. Note the insulation between the support and the anode.
The anode is connected to the base pin by a length of ribbon.
Looking into the grid bell reveals no details.
Many thanks to Mike Homar for donating this wonderful exhibit.
The thin glass tube envelope is 22 mm in diameter, and excluding the B9A base pins is 48 mm tall.