EF36 EF37 EF37A ME1400 CV358 CV432 CV1056 CV1404 NR49 OM5 VR56 AUDIO PENTODE VARIOUS

Octal based audio amplification pentode.
Manufacturer: Cossor

Oh what a tangled web and where do we start, OK, Mullard brought out their red coated general purpose pentode, the EF36 in 1940, a good valve though prone to short life and induced hum, this was the valve of choice in some pretty spesh kit including the famed Leak TL12.1 and indeed the code breaking Colossus computer. 

By 1946, improvements were made to the EF36 to try and counter the hum problem and the valve was designated the EF37.

By 1951 a final crack at the problem was made and this time, Mullard got it exactly right with the EF37A courtesy of a bifilar heater winding – at last the EF37 was bombproof – in fact so much so that the construction techniques learnt and the specifications achieved were carried over into the EF37A’s spiritual B9A based successor the EF86.

Mullard had one last iteration of the EF37A in the ME1400, developed for the GPO; this was an ultra high quality low noise variant for use in electrometer circuits but today is especially prized for use in studio audio equipment.

EF36 CV1056 NIB
Stock Code: CX P Y
Availability: 4 in stock
Delivery date: 1 week
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