Beschrijving
Very early Valvo ECC81 (labeled Philips Miniwatt). Coin base version; 1953, bended horse shoe getter.
Once in a life time!
Description
This pair ECC81 Philips Miniwatt is produced by Valvo in Hamburg Germany. The tubes the very first ECC81 version that Valvo has produced; June 1953. The tubes inner is clearly of early production; the complete electrode pack is welded to the base pins. The getter is a bended horse shoe shape. The plate is rounded. The tube has copper grid posts, see pictures. Very healthy tube with excellent specs!
The early Philips/Valvo productions of noval tubes were run on the same lines already in use for rimlock valves. These productions are identifiable by the sharp and regular edge of the base, glass frit bonded or glazed to the body. Another peculiar feature of these tubes is that the electrode pack is firmly welded to some of the base pins, no large mica spacers pressed against the internal wall of the envelope.
Sonics
Several sources praise this ECC81 version as being among the best (the earlier the better!). This tube produces a sound from the early history of the ECC81 double triode; a mystery.
Note from the web:Valvo ECC81 tubes, particularly those with a “coin base” and/or “d-getter” and especially those made in Hamburg before 1955, are highly sought after by audio enthusiasts and collectors. These tubes are known for their excellent sound quality and build quality. The “coin base” refers to a specific design element of the tube’s base, while the “d-getter” refers to a type of getter material used in the tube.
Test results*
The measurement data below illustrate that both tubes are in NOS condition. The internal balance between the triode sections is excellent. And the tubes form a perfect pair!
| Valve
V141 |
Ia (plate current):
Transconductance (Gm): Gas test, Shorts test: |
8.6 / 8,4 mA
5,3 /5,2 mA/V OK |
= NOS / NOS
= NOS / NOS
|
| Valve
V141 |
Ia (plate current):
Transconductance (Gm): Gas test, Shorts test: |
10,6 / 10,3 mA
4,9 /5,0 mA/V OK |
= NOS / NOS
= NOS / NOS
|
* Where NOS is : Ia = 7,0 to 14,0mA, Gm= 4,5 to 6,5 mA/V. (Telefunken factory specification see test page)
Short description
| Tube type | ECC81 |
| Quantity of Tubes | One pair |
| Brand | Valvo |
| Manufactured in | Hamburg, Germany |
| Tube codes | YKB D4 (June 1953) |
| Construction | Rounded plates, soldered on pins and copper grid posts, coin base |
| Getter Construction | Bended horse shoe getter |
| Print Condition | Pristine See pictures |
| Box included | Generic Valvo factory box |
| Equivalent tubes: | 12AT7, ECC801S, 12AT7A, E81CC |
| General test results | NOS |
