Burn Tested

Each vacuum tube is burned-in for a minimum of 48 hours dissipating full power with filament, plate and screen voltages that are normally used in amplifier applications. All of this ensures that the various electrical parameters have stabilized and the matching of each vacuum tube will not drift during the life time of each audio tube.


Our power tubes are matched within 5% variation on all parameters. We start the process by using audio tubes that are tested for bogey values and reject those that are on the outside limits of their design. Each vacuum tube is then tested on our fleet of wt-100a original RCA production testers for plate current, screen current and transconductance (gm). We also check for grid current and leakage between elements.

Matching – Matched Pair; Matched Trio; Matched Quad

Vacuum tubes are manufactured to perform in a broad electrical range of based on design characteristics. Because of the variance during manufacturing, there may be as much as a 25% difference in test results in any given production run. Amplifiers that have one bias adjustment for multiple tube applications are required to use matched power tubes to optimize tube performance as well as maximizing the life expectancy. On amplifiers that have individual bias controls, it’s not typically necessary to have matched vacuum tubes.

Although our experience over the last 30 years has indicated that sonic performance is enhanced when each vacuum tube exhibits the same electrical characteristics in any given circuit design. Our matched vacuum tubes go through rigorous test procedures to enhance performance during their operation.

When you receive vacuum tubes from Penta Labs that are matched you can rest assured that you are receiving a product that has been thoroughly tested and will perform at levels unsurpassed in the industry.