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 signs 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 “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!
Valvo’s Hamburg production has a good reputation among tube enthusiasts. Experiences with this 6201 SQ mainly point to:
-
- A very open and detailed high.
- A nice layered sound image.
- A natural representation of voices.
- A tight layer without excessive thickness.
- An excellent placement of instruments.
This is typically a tube for someone who loves detail, spaciousness and a natural rendering, without excessive heat or coloring. The Valvo is described by some listeners as a middle ground between the fast, lively Siemens and the somewhat smoother, warmer Mullard.
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
| Tube type | 6201 |
| Quantity of Tubes | One pair |
| Brand | Philips Miniwatt |
| Manufactured in | Valvo factory, Berlin Germany |
| Etch code | Both tubes Df6 D 3H3 (1963) |
| Construction | Frame grid, gold pins |
| Getter Construction | Halo |
| Print Condition | See pictures |
| Box included | Oriinal factory box |
| Equivalent tubes: | 12AT7, ECC81, 12AT7WA, ECC801S |
| General test results | NOS |
