Mullard 12AX7 / ECC83 - matched pair, shield logo

The 1961 Mullard 12AX7 / ECC83 tubes in this precisely matched pair have gray plates with copper grid posts and halo getters (I61 series). The white labels have the early Mullard shield logo and the Blackburn factory code is etched in the glass.  Both tubes test as new with very low noise. They are matched for both current draw (mA) and transconductance (Gm). They ship in new white boxes. These tubes are sold as a matched pair. Photo is of actual pair. Singles, when available, are listed as Item 330.