ECC81 -12AT7 ADZAM (Philips Suresnes RARE 60's year !) NOS-NIB Pair (v219 - v221)
MATCHED PAIR ECC81 - 12AT7 ADZAM (By Philips Suresnes Plant France RARE 60's year !) Balanced Triodes for Ip & Gm on 8 measurements, codes TK2 F3C2 e TK2 F4C5, 2 Ribbed Grey Plates, Top O Ring Getter, in Original Box (v219 - v221)
These are NOS Tubes (New from Old Stock no longer in production)almost certainly already tested in the factory at the time but before the sale they are tested by us one by one, to do this we use our TTA (the warmer) that allows us to heat up to 20 valves simultaneously and then perform the measurements with the "Characteristic Meter Avo VCM 163 "so the heating time will be the same for the whole lot in order to obtain precise and reliable relative numbers for the subsequent selection made with a software developed by us that compares all the values of Ip and Gm of the whole lot (80 total measurements for 20 tubes lot) and extrapolates the singles, the pairs, the triplett, the quartets to various tolerances.
consider that for each Tube (double triode) there are four measurements to be agreed (Ip and Gm for each triode)
For traceability the Tubes are individually numbered on bulb/base and inside the box, other numbers that you read inside the box are NOT the values but are our references for recording the measurements on our archive.
For information we specify that the measurements are performed at constant Va, therefore having Ip and Gm within certain tolerances, also the Ra and the μ will be similar.
- Burned, Tested, Selected by Audiokit with TTA+ AVO VCM 163 + AKi Matching Software
- ins 31/1/2022 MZ