Check1.2 - Feedback Checker

Check1.2 finds the frequencies most likely to feed back, in Hz. Before the show, you cannot tell which frequency to pull down. The iPhone microphone is all you need. No measuring instrument, no external microphone.

The Full version is a one-time purchase. It is not a subscription.

FREE AND FULL - Stereo recording: free is 5 minutes a take, 2 saved. Full records a whole show in one take and keeps all. - Monitor check results: free keeps 3. Full keeps as many as you like, compares with your last visit to the same venue, and keeps what you changed. - Normalize: free works on takes up to 5 minutes. Full works on longer takes too. - Ear training quiz: free is Beginner, 6 bands, 2 sets a day. Full adds Advanced, 21 bands, unlimited sets. - A/B comparison: free is Pop. Full has four genres. - Instrument views: free All. Full adds drums, bass, guitar, vocal, piano. - Spectrogram: free 3 times a day. Full unlimited. - Speaker check measurement, export of results, Pan position quiz: Full. Use Restore Purchases on a new device.

Analyzer, Monitor check, voice registration, Metronome, Tuner and Speaker check are free. Spectrogram 3 times a day. No account needed. Try Full free for 7 days; it returns to free with no charge. Works on iPad too.

For people learning PA, people doing the PA on the day at a small venue with no dedicated engineer, and people training new PA staff at a live house.

FEATURES - Stereo recording, no compressor and no limiter. - Metronome with a volume slider and a beat-1 accent you can turn on or off. - Tuner. Press a note name to hear it as a sine tone. - Speaker check.

MONITOR CHECK (BEFORE THE SHOW) From 15 seconds of ambient sound and your voice, it lists the bands most likely to feed back, as a number and a word, like "about 250 Hz (muddy)". While recording, a green, yellow or red lamp warns you when feedback is close. Register your voice and it also reports muddy (200-500 Hz), boomy low end (63-125 Hz), harsh (2-5 kHz) and sibilance (5-8 kHz).

A tone that stays after your voice stops is close to feedback. It listens 3 seconds to tell it from reverberation. Results stay on your iPhone with the venue name and a note, so you can compare next time.

What you do next is the real work. Turn the level down. Move the speakers or the microphone. If it still feeds back, cut the band you found with EQ, a little at a time.

ANALYZER (DURING THE SHOW) 50 Hz to 18,000 Hz, about 11.7 Hz steps, redrawn about 23 times a second.

- Green line: the sound now. White: Peak Hold. Orange dashed: the strong band. - A tone that stands out from its neighbours and keeps doing so gets a solid red line. Musical notes are told apart by their harmonics and get no red line. - Drag the screen to read the frequency there. Pick an instrument (All, Drums, Bass, Guitar, Vocals, Piano) for notes written for it. - If the waveform goes flat on top, it tells you it is clipping.

FREQUENCY QUIZ Name the frequency of a sine tone, or compare a band track with and without EQ and name the band that changed. With headphones and Advanced (full version), 63 Hz and 125 Hz join in.

HOW TO USE Monitor Check measures the ambient sound for 15 seconds. Record your voice, press "See results" and wait 3 seconds. Read the bands most likely to feed back and what to do next.

PRIVACY Recording, analysis, voice registration, results and venue notes stay on your iPhone. The app never sends them anywhere. The only network use is Apple's in-app purchase. No ads, no tracking.

NOTES This app is not a measuring instrument. Start quiet and raise the level slowly. Stereo recording works on supported models only; others record in mono, and the app tells you first. Below 150 Hz the iPhone microphone cannot measure accurately, so feedback detection is off there. dB is not calibrated.