6189 - 12AU7WA - ECC82 JAN General Electric USA NOS - 2% SPECIAL SELECTION - Single (v277)

THE BEST ! THE MOST PRECISE! with very tight tolerances, they are chosen by us during the normal selection for the coupling, to consider that out a pair so at least every 20-30 tubes measured, considering that for each tube (double triode) there four measurements to agree (Ip e Gm for each triode) then for the pair of tubes the measurements are well EIGHT and the declared tolerance concerns the comparison of all the eight measurements, in these cases it often happens that the measurements of each single tube are even at 0% or 2% tolerance

To achieve this we use our TTA (the warmer) which allows us to heat up to 20 tubes at the same timeand then perform the measurements with the "Characteristic Meter Avo VCM 163" so the heating time will be the same for the whole lot so as to obtain precise and reliable relative numbers for the subsequent selection made with software developed by us that compares all the values ​​of Ip and Gm of the whole lot (80 total measurements) and extrapolates the pairs, triplets, quartets to the various tolerances.

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 close tolerances, also the Ra and the μ will be.