6201 SQ (ECC801S) Philips Miniwatt, NOS, gold pins, halo getter (V60)

Beschrijving

Long life SQ (Special Quality) ECC81 tubes !

This is a 6201 Philips Miniwatt tube. It is produced by the Philips subsidiary Valvo in 1963 in the Hamburg Valvo factories. The tube bears the etch code PTT which means that it was ment for the Dutch post company. The tube has a halo getter, a half box plate structure, and gold pins, see pictures. Healthy tube with NOS specs! Tube with matching triode systems; see test results. The tube shows no sins of use and is assumed to be unused. 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. The SQ marking means Special Quality! 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 “very warm sounding” tubes, and to some ears their lower of midrange warmth may be interpreted as transparent/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 tube tests NOS. The internal balance between the triode sections is excellent. The measurement data below illustrate that the tube is in excellent condition. 

Valve V60

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

9,6 / 10,3  mA 5,5 /5,9 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