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  The Bias King™
  A Diagnostic Tool for Measuring the Bias on Vacuum Tube Amplifiers

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  • Works on most octal socket tube amps
  • Small enough to carry in most guitar cases
  • Requires no power source other than amp it’s plugged into
  • No expensive batteries to replace
  • Can be used to “match” tubes into pairs

Your amplifier tubes need the BIAS KING™!

Photo of the Bias King with tube attachedAs tubes age, their bias point will shift. By using the Bias King you can maintain the sound you want by periodically adjusting the bias on your amp. This will keep your tubes in top shape throughout their life and will keep your amp sounding its best.

The Bias King is a simple, effective, and accurate diagnostic tool designed to read the current flowing through the tube of an amplifier (bias). The bias on an amplifier can be adjusted by a technician to allow more or less current to flow. The more current there is flowing, the higher the numbers will be on the Bias King and the hotter the tubes will run. The tubes will also sound different depending on where the bias is set.

Although the Bias King will not set the bias for you, you can use the chart printed on the side of the Bias King to find out what range of current flow is acceptable for the particular tube type you are using in your amp. To keep your tubes in good shape and your sound consistent, periodically checking the bias of your amp is extremely important.

The Bias King is a must have whether you're in a recording studio or on the road.



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