12AT7A Pair Brimar (V1/58)

Description

This is a pair ECC81 produced by Brimar in the sixties in the UK. The tubes have a special halo getter, copper grid posts and ribbed plates which are bended into a kind of box structure, see pictures. Very healthy tubes with NOS specs! Tubes with matching triode systems; see test results. The halo getter has a non standard structure, more like the horse shoe types. See first picture.

The tubes look and measure unused; see pins!

Sonics

The early British ECC83 tubes of Brimar and Mullard are famous for their beautiful sonic character. I refer to the many threads on the web for more information. This is pair an excellent example. Balanced and smooth sounding with liquid midrange, recommended!

Note: if your system is to “warm”, this tube is not a first choice. ECC83 tubes of Philips, Valvo or to a lesser extent Telefunken are to be considered in that situation. 

Test results*

Valve 1 V1	Ia (plate current): Transconductance (Gm): Gas test, Shorts test:	8,2/ 8,6 mA       5,7/ 5,2  mA/V OK	=  NOS =  NOS
Valve 2 V58	Ia (plate current): Transconductance (Gm): Gas test, Shorts test:	12,2/ 11,5 mA 6,3/ 6,3  mA/V OK	= NOS = NOS

Where NOS is : Ia = 7 to 14 mA, Gm= 4,5 to 6,5 mA/V. 

  *  For test methods and factory specification read the tube testing page.

Short description