Tube-amp bias calculatorFree
Bias Bench
A free calculator for fixed and cathode bias, push-pull and single-ended, with screen-grid current and PSU sag accounted for. The math from the tech pages, done for you.
Tools · Free
Tools From the Bench
Calculators and utilities that came out of real repair work. Free, no account, no catch — if it saves you a botched bias job, it did its job.
Interactive tone stack calculatorFree
Tone Stack Lab
Turn a real amp's tone controls and watch the frequency response move — then hear it. 55 component-value presets across 15 circuit families.
Presence & resonance feedback simulatorFree
Feedback Lab
What a presence knob really does: 29 amps simulated as real closed feedback loops — response at the speaker, feedback vs frequency, damping factor, reactive cab models.
JFET/MOSFET workbench for audio circuitsFree
FET Playground
Measure a real JFET with a multimeter and a resistor, then design a common-source gain stage around that exact part — not a datasheet typical. Live schematic, transfer and output curves, load line, frequency response, SPICE export.
