EL84 - 6BQ5 GENERAL NOS-NIB Quartet v24-36-37-39)

These are NOS Tubes (New from Old Stock no longer in production)almost certainly already burned & 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 Tubes 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 (40 total measurements for 20 tubes lot) and extrapolates the singles, the pairs, the triplett, the quartets etc. to various tolerances.

consider that for each Tube (pentode) there are Two measurements (Ip and Gm) so for the sextet of Tubes the measurements to be agreed are well TWELVE

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.

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.