Tube Testing and Matching
Power tubes are subjected to a 5 stage test before shipping.
- Each tube is measured for transconductance and current draw with 400 volts on the plates. Measuring at real amp voltages is the only way to assure a tube will work correctly in an amplifier. Many tube testers measure at 150 volts or less.
- Each tube is tested for noise and microphonics. Rejected tubes are discarded.
- Each tube is burned in for up to 48 hours. Since most new electronic components that will fail prematurely fail very early in life ("infant mortality"), the burn in process weeds out potential defects before you receive them. Burning in is also critical to eliminate "drift". This assures that matched pairs stay matched as they age.
- After burn in, power tubes are digitally matched for both mutual conductance (within 5%) and current draw (within 3mA but usually closer @ Vplate ~= 400Volts) on a Maxi-Matcher. Closer matching available on request.
- Finally, matched pairs are tested in an amplifier as a final check for matching, noise and microphonics.
Preamp tubes are tested for gain, noise and microphonics on a VTV Triode Characteriser before shipping. Balanced triodes are available on most preamp tubes at additional cost.
We will be happy to provide tubes for your Mesa Boogie amplifiers. When ordering power tubes, please state that they are for a Mesa Boogie amp and we will select tubes in the correct bias range.