2 MATCHED MULLARD ECC83 12AX7 MADE MARCH 1962 TESTED
Codes: Valve 1: I61B2C2; Valve 2: I61B2C3;
Both made at Mullard's Blackburn factory, England, UK. in 2nd and 3rd weeks of March, 1962. Just pre-dating Mullard's yellow-print period.
Large halo getters.
Seamed envelope construction.
Old shield logo.
The I61 was the first design of ecc83 to follow Mullard's long plates.
These early short-plate-design ecc83's feature juicy-sounding copper posts, which were phased out by the mid-1960's.
Tested good for shorts; continuity; microphony; and emissions.
No hiss, no hum, no noise, no microphonics. Guaranteed.
Emissions test circa 100% compared to nos valves at specified test voltage of 12.6v.
Life test: 100% and 80% respectively. Valves are lightly used.
Test results: Valve 1: triode 1: 69; triode 2: 69;
Test results: Valve 2: triode 1: 67; triode 2: 68;
NOS (unused) vintage Mullard ECC83's typically score around 68 per triode on the tester used. (Below 41 is 'bad').
NB: Valves tested at specified voltage of 12.6v. Tester does not test transconductance.
12AT7もMullard ECC81に交換。All Vintage Mullard にして現在バーンイン中。