TubeBias: Amp Bias Calc

Yoshifumi Sato · Utilities

$4.99

Independent analytics for this App Store listing. AppTracker is not affiliated with Yoshifumi Sato.

Chart standing · US

Not currently charting in this storefront.

What changed · US

Listing changes AppTracker has observed for this app in this storefront — new versions, price moves, rating shifts, and store copy.

Sep 14, 2026
New version 1.0 → 1.0.1

Fixed a bug where recent changes could occasionally be lost if the app was closed right after editing values. Your inputs are now saved immediately when you leave the app.

In-app purchases · US

No in-app purchases.

Screenshots

Similar apps

Competitors and close alternatives, as estimated by AppTracker.

About

TubeBias helps you bias a vacuum-tube amplifier and match its output transformer, with a clear safe-zone readout. Enter plate voltage and idle current to get plate dissipation and its percentage of the tube's rating, with a green/amber/red safe-zone check. Solve the bias current for a target percentage, or work out cathode-resistor bias. On the impedance side, compute reflected primary impedance, turns ratio and per-tap loads for your speaker. FEATURES • Plate dissipation and bias % with safe-zone check • Target-% bias current solver • Cathode-resistor bias • Reflected impedance, turns ratio, tap selection • Common tube presets (EL84, 6V6, EL34, 6L6GC, KT88, 300B) • Save your setups No ads, no tracking, no account. A one-time purchase. Safety: high voltage is dangerous. These calculations are a guide only; work at your own risk and have a qualified person verify.

What's new · 1.0.1

Fixed a bug where recent changes could occasionally be lost if the app was closed right after editing values. Your inputs are now saved immediately when you leave the app.

Details

ReleasedAug 2026
UpdatedAug 2026
Version1.0.1
Size12 MB
RequiresiOS 17.0 or later
Age rating4+
LanguagesEnglish, Japanese
Price$4.99
Categories Utilities
Bundle IDcom.madeinchimpanzee.TubeBias