The Tung-Sol 6550 Solid Grey Plate is a rare 6550 manufactured in the late 1950s and early 1960s. These tubes are known to have the tone of the Tung-Sol 6550 black plate, but the extension of the Tung-Sol 6550 3 hole grey plate. This tube was the US answer to the GEC KT88 and was used interchangeably. This is an incredibly musical tube, with a linear presentation and a tight bottom end. We have two pairs available, or a single matched quad. These tubes will be shipped in white boxes unless the original boxes are requested, please be aware that the original boxes were previously in a home with smoke in it.
All tubes are tested on a AT1000 computerized tube tester at real world operating voltages (450 volts in the case of the 6550), one tested tubes are also matched at those voltages. For power tubes we match based on EM first and then GM. For small signal tubes we match based on GM then EM.
Please be aware that vintage vacuum tubes are antiques and carry no guarantee or warranty. We provide a sheet explaining what you purchased, your test results for your tubes, and if need be can provide photographs of the tube on the tube tester before we pack and ship them.