About TAD premium tubes:
TAD does all TAD Tube quality control processing in-house under strict control of our technical staff. Our techs which are also musicians and guitar players, developed and constructed our custom tube testing systems and aging rigs to run tubes in real amplifier circuits and operation conditions.
For TAD, real tube quality control is way more than just a simple test. Before a TAD Tube gets accepted at all we perform extensive sample evaluation testing for consistency, power test, shock resistance test, soak test (long term operation at full power) and of course a musical test in known amplifiers to learn about its sound character in different styles. The main tests are made after a propper pre-aging to stabilize the cathode emission. While most tube test equipment does work at 250V as a maximum we built our test rig to operate at voltages of 360 to 600V depending on the tubes being tested. Every TAD Tube is tested by our qualified staff. Each pentode is inspected,tapped while operating and listened for noise floor, hum and odd noise.
Finally measured for a set of parameters and matched by Ia (PC) and Gm (TC). We do test batches of 400 to 500 pieces per run to allow tightest tolerances of typically 0.5mA for PC. All TAD Tubes and boxes get labeled with the PC and TC test results and a unique serial number to identify every tube we’ve ever tested. We permanently verify and monitor selected and matched TAD Tubes by using them every day in our own amp service department and in the TAD Amp Kits we assemble. This is the most complete quality control system we can imagine.
All done in-house at TAD in Germany