FTBC (“Freedom Tube Bias Calculator”) is definitely not your average tube bias calculator app. It has been designed to give you the freedom to set it and use it the way you want to. “Freedom” is the keyword here.

► FTBC view
- Two calculation modes so you can calculate either the Bias % or the Plate Current at any given moment.
- More than 100 available tube types to choose from and you still have the freedom to manually put your own Maximum Plate Dissipation value if you want to.
- Get notified when the Plate Voltage value you put in the respective field of the FTBC view exceeds the maximum safe operating voltage of the tube type you have chosen.

► Preset view
- Edit, manage and save your custom presets (20 in total) in the Preset view and directly retrieve them on demand from the FTBC view.
- Make the application fill the respective fields with your chosen preset’s values automatically, every time the app starts.

► Settings view
- Make the Bias field in the FTBC view change color (blue, green or red) depending on your Biasing Type/Class selection and the respective thresholds.
- Set your own thresholds to define the safe/optimal bias range per Class/Biasing Type combination.
- Make the application start on the calculation mode, class and biasing type of your choice.

► Key features
- All values are selected using pickers throughout the app (no virtual keyboards unless you want to edit a Preset name in the Preset view).
- Even if you own a device with a relatively small screen and the picker covers up a significant part of it, you will always know which field you are currently editing thanks to the indicator at top of the view.
- Works in both portrait and landscape orientations on iPads (on iPhones it’s limited to portrait orientation only, for practical reasons).
- Notification when the Plate Voltage value you put in the respective field of the FTBC view exceeds the maximum safe operating voltage of the tube type you have chosen.
- Adjustable sound notifications per event and lots of sounds to choose from.
- Adjustable vibration notification per event (available only on iPhones).
- Option to enable/disable specific Tube Type groups (Twin Triodes, Triodes, Tetrodes and Pentodes)
- Option to disable the background images.
- Option to disable some of the animations.
- No Internet connection is needed.
- FTBC is and will always be Ad-free.
- You can watch videos that walk you through the app’s functionalities and features here:

If you have any questions, suggestions, problems or feedback, don’t hesitate to contact me at (please make sure “FTBC” is included in the subject of the email, preferably at the beginning).

What's New

Version 1.3.3

- A "Rate FTBC" button has been added to the Information view.
- Code optimization for iOS 11
- User Guide has been updated

Ratings and Reviews


Total Impact DJ

Completely useless without purchase. Don't waste your time there's plenty of info on the Internet, just use a calculator.

Scam app


App claims to be a free version but once you've downloaded it and plugged in all the info it asks you to buy before you can use it.... Dishonest.


33.6 MB
Requires iOS 8.0 or later. Compatible with iPhone, iPad, and iPod touch.
Age Rating
Rated 4+
© 2015 Nikolaos Skampas


  • Family Sharing

    With Family Sharing set up, up to six family members can use this app.

More By This Developer

You May Also Like