Tube power amplifiers need to have a bias current applied to their tubes to regulate the amount of electron flow, creating the proper current flow. It is important to keep that bias current at its correct level as tubes break in and as they age. It’s not always easy to dig out a multimeter, make sure its batteries are good, and then remember where to set it to get the correct reading.
Cary Audio’s MA-300 is a single-purpose meter, only measuring milliamps of DC current, and with an installed connector, all mounted in an attractive steel stand. This makes it very easy to plug it in to any of our amplifiers and get an instant reading of each channel’s bias. A simple adjustment with a small screwdriver will turn it up or down until the meter reads the proper level, and you’ll have the best performance from your amplifier once again.