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.
TAD – Products 2010 /2011 7
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.
meeting 5881 specs
TAD matching label
TAD logo and tube type
lead free solder
serial number, each tube has
an individual number
TC = Transconductance (gm) in micromhos/10.
The higher the TC number is, the more dynamic
this tube amplifies
PC = plate current in mA
drawn in our test circuit