SignalKit - RTA & Audio Tools

SignalKit is an audio analysis toolkit for sound engineers, AV technicians and anyone tuning a room or a sound system. A real-time analyzer, SPL readouts, a signal generator and a set of measurement tools in one app, with an in-app manual that explains each one.

FREE

REAL-TIME ANALYZER (RTA)
- Live spectrum in 1/1, 1/3, 1/6, 1/12 or 1/24 octave bands
- A, C and Z weighting
- dB, Peak, RMS and Leq readouts
- Fast, Mid, Slow and Impulse time weighting
- Peak hold with adjustable fall time
- Pinch to zoom the chart, pinned frequency readout, optional musical note on the peak
- NC and NR noise ratings from the octave bands
- Choose the chart background, grid and bar colors
- Save target traces with no limit, overlay them on the live spectrum, sort them into folders
- Capture chart snapshots and record sessions over time

CALIBRATION
- Broadband offset against an acoustic calibrator or a meter you trust
- Import a microphone correction file (.txt or .frd)

SIGNAL GENERATOR
- Pink, white and M-Noise
- Sine at any frequency, sweeps with loop and loop-reverse modes, multitone
- Output level in dBFS
- Export any signal as a WAV file
- Song player: play your own MP3 or WAV files and watch them on the RTA

SYSTEM TEST
- Play a reference signal, compare the return with a saved baseline, see the per-band differences, share a PDF report

WIRELESS LINK
- Pair two phones on the same WiFi with a QR code
- One phone measures, the other shows the readings live
- If the measuring phone allows it, the viewing phone can start, stop and set its RTA

EXPORT
- Recorded sessions export as CSV or PDF
- The in-app manual prints to PDF

PRO (one-time purchase, not a subscription)
- Transfer function: dual-channel magnitude, phase and coherence
- Delay align: time-align speakers to a reference position
- Impulse response capture, with RT60 and STI computed from it
- RT60 reverberation time (ISO 3382 interrupted noise), with multi-position averaging
- STI / STIPA speech intelligibility (IEC 60268-16), with multi-position averaging
- Spectrograph waterfall
- Polarity test, including a live mode for a handheld polarity checker
- Distortion (THD)
- Auto-EQ: suggested filters from a saved target and a room spectrum
- PDF reports of saved measurements, snapshots and targets
- Use a USB measurement microphone as the input (Dayton, miniDSP UMIK, iSEMcon, Earthworks and similar)
- Removes ads

The free version shows ads. One Pro purchase unlocks everything above; there are no add-ons to buy on top of it. Bought the old STI or RT60 add-on? It stays yours: tap Restore Purchases.

LOCAL-FIRST
- No account
- Measurements are stored on your device and leave it only when you export or share them

A NOTE ON PHONE MICS
A phone microphone is not a measurement microphone. Calibrate before you rely on an SPL number, and use a USB measurement mic with its correction file when the number has to hold up.

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

Recent changes:
Export as WAV: files of 5 minutes and more show a note that the export can take several minutes. A typed custom duration now shows in Selected straight away.