20 Mar
Tube Bias Calculator

Posted by Rob Robinette in Music & Audio | March 20, 2015 | 3 Comments

Apk file size: 1.6 MB

The Tube Bias Calculator will calculate power tube bias values of Plate Current, Dissipation and % of Max Dissipation using either measured voltage drop across a cathode resistor or measured plate current. It has a database of 36 tube types and will calculate the Class A Fixed, Class AB Fixed Bias and Cathode Bias Maximum Safe Bias settings.

To calculate the tube's Max Safe Bias setting you simply pick your tube from the pick list and enter the Plate-to-Cathode Voltage (plate voltage is always measured between the tube's plate and cathode). The Maximum Safe Bias settings for Class A Fixed, Class AB Fixed Bias and Cathode Bias are displayed.

To calculate bias when you measure the plate current, such as when using the output transformer shunt current measurement, enter your Tube Type and Plate-to-Cathode voltage at the top of the page, enter the Plate Current and touch 'Calculate' and the Plate Dissipation and Dissipation% are shown.

To calculate bias by measuring the voltage drop across a cathode resistor enter your Tube Type and Plate-to-Cathode voltage at the top of the page, enter the Number of Tubes that share the cathode resistor, the Voltage Drop Across the Cathode Resistor and the Cathode Resistor actual resistance. Touch 'Calculate' and the Total Cathode Current, Total Plate Current, Plate Dissipation, Plate Dissipation % & Current per Tube are shown.

To measure the voltage drop across a resistor set your multimeter to volts DC and touch each leg of the resistor with a probe (disregard any minus sign).

WARNING: Amplifiers have high voltage that can KILL even when unplugged. Do not attempt to set an amplifier's bias unless you are competent with test gear and very familiar with high voltage and the dangers involved.

#### Whats new

V1.9.3 Added 12AU7 to tube database.
V1.9.2 Minor editing.
V1.9.1 Removed redundant Plate-to-Cathode Voltage input.
V1.9 Minor editing.
V1.8 Changed 'Plate Voltage' to 'Plate-to-Cathode Voltage. Minor format changes.
V1.7 Corrected 'Bias Using Plate Current' calculation bug.
V1.6 Added 5 new tubes to the database.
V1.5 Minor changes.
V1.4 Minor format changes.
V1.3 Added more tubes to the database and more detail on the Help page.

Rob Robinette part of our Music & Audio and have average installs from 1000 to 5000. Last Update March 20, 2015. Google play rating is 77.7778. Current verison is 1.9.4. Actual size 1.6 MB.

#### Jayson Starkey

Great App for Amp Techs This is an awesome app. The author of this app is also probably the greatest resource on the net for 5E3 builders. If you get the chance read through his website. It is a wealth of knowledge for builders and techs.

#### Dave V

Love it Exactly what's needed to swap tubes and set a correct bias.

#### Ted Van Matje

10 star app! Rob! Excellent work man! This app has just made my life infinitely easier. You deserve lots of high quality cold Beer. Thankyou * 10^666 ;)