SignalKit - RTA & Audio Tools

SignalKit is a professional-grade audio analysis toolkit built for sound engineers, AV technicians, and tuning enthusiasts. Designed to be a portable replacement for stand-alone analyzers in field work, system tuning, and acoustic measurement.

REAL-TIME ANALYZER (RTA)
- Live FFT spectrum from 20 Hz to 20 kHz
- 1/1, 1/3, 1/6, 1/12, 1/24 octave bands
- A, C, and Z weighting
- Pinch-to-zoom on the spectrum chart
- Peak hold with adjustable fall time
- Save target traces and stack up to 30 for comparison
- Customizable colors (chart background, grid, bars)
- Tap any band to lock and read its level

SPL METER
- Live broadband measurement with Fast/Slow time-weighting
- Peak, RMS, and Leq (energy-averaged) readouts
- A, C, Z weighting toggle
- Calibration offset for matched reference levels

SIGNAL GENERATOR
- Pink, white, and M-noise sources
- Sine wave with user-defined frequency
- Sweep generator with 3 loop modes
- Output level picker (dBFS)
- Export signals as WAV files

MEASUREMENT TOOLS
- STI / STIPA speech intelligibility (paid add-on)
- Impulse response capture and analysis
- Polarity check tool

WIRELESS DEVICE LINK
- Pair two phones over WiFi via QR code
- One phone measures, the other displays the data in real time
- Useful when the mic position can't reach the operator

LOCAL-FIRST
- All measurements stay on your device
- Optional WAV export via local share sheet
- No account required, no cloud sync of your measurements

FREE & PRO
- The core RTA, SPL meter, and signal generator are free to use
- The free version is supported by ads
- A one-time Pro purchase removes ads (and unlocks the paid measurement add-ons)

Privacy policy: https://griswoldlabs.com/privacy/signalkit/

Recent changes:
New: control a remote SignalKit from the board over the Wireless Link (Start, Stop and settings). The signal generator keeps playing when you leave the app. The USB mic warning shows once per app open. Tap the pinned frequency readout to open its settings. Many fixes since 1.0.9.