6201 Philips Miniwatt, NIB, same date, gold pins (V104 / 105)

Description

Long life SQ ECC81 tubes !

This is a pair 6201 Philips Miniwatt tubes. They are produced by the Philips subsidiary Valvo in 1963 in the Hamburg Valvo factories. The tubes have a halo getter, a half box plate structure, and gold pins, see pictures. Healthy tubes with NOS specs! Tubes with matching triode systems; see test results.  The tubes show no sins of use and are assumed to be new.. This is the longlife, tight tolerance version of the ECC81/12AT7. This tube was made exclusively for governmental institutions and manufacturers of high precision gear. Overall, the 6201 tube is a step up from the standard 12AT7.

Sonics

Note from the WEB: These tubes are characterized by an impressive open “air” at the top end. The soundstage is large. The midrange is flat, and the bass is tight and accurate. These tubes have a fine sense of dynamics, and most are impressively quiet. These are not “warm” tubes, and to some ears their lack of midrange warmth may be heard as bright. I tend to think of them as accurate, and their clean, focused sonic image is astonishing.  They are absolutely incredible tubes that will never be made again!

Test results*

The tubes tests NOS. The internal balance between the triode sections is excellent and both tubes are matched nicely. The measurement data below illustrate that the tube are in excellent condition. 

Valve V104

Ia (plate current): Transconductance (Gm): Gas test, Shorts test:

11,0 / 11,3  mA     6,6 /6,7 mA/V OK

=  NOS / NOS =  NOS / NOS

Valve V105

Ia (plate current): Transconductance (Gm): Gas test, Shorts test:

11,3 / 11,9  mA     6,7 /6,8 mA/V OK

=  NOS / NOS =  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