Made in W.Germany.
This tube is two independent triodes within the single envelope and with a gain of 30 would be useful for most purposes including instrumentation. As a low-microphony double triode with separate cathodes, primarily intended for use as an AF voltage amplifier or phase splitter.
Nos in original box. Matched pair are available.
Made in G.Britain by Mullard.
Mullard designate the EF37A as a high gain, high impenance, pentode for use in AF pre-amplifier stages. The electrode system is of anti-microphonic construction, and the specially designed heater reduces hum to negligible proportions.
Nos inoriginal box. Matched pair are available