Check1.2
Ring out stage monitors with your iPhone. Check1.2 shows, in Hz, the bands most likely to feed back. Free to start, no external mic.
A startup from Japan.
Ring out stage monitors with your iPhone. Check1.2 shows, in Hz, the bands most likely to feed back. Free to start, no external mic.
A startup from Japan.
This page is designed to help you find out whether Check1.2 is good and if it is the right choice for you.
Check1.2 is an iPhone app for live sound and band practice. It finds the frequencies most likely to feed back, in Hz, using only the iPhone microphone. No measuring instrument and no external microphone are needed.
New in version 2.11 (October 2026) - Daily Ear Training (free): the same 10 questions for everyone worldwide, every day, with a Game Center ranking. - Video: capture gigs and rehearsals with the camera picture and stereo sound in one video (Full version, also in the 7-day trial). - Band Timing Check: set a target tempo for each song, compare with your last take, export a PDF, and split back-to-back songs with markers (Full version). - Stereo recording keeps music playing while you record, and stops from the Lock Screen and Dynamic Island.
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)". Results stay on your iPhone with the venue name and a note, so you can compare next time.
Analyzer (during the show) — 50 Hz to 18,000 Hz, redrawn about 23 times a second. A tone that stands out from its neighbours and keeps doing so gets a red line.
Also included — Stereo recording with no compressor or limiter, Metronome, Tuner, Speaker check and a frequency quiz.
Price — Free to download, no account, no ads, no tracking. The Full version is a one-time purchase, not a subscription, with a 7-day free trial that returns to free with no charge.
For people learning PA, people doing the PA at a small venue with no dedicated engineer, people training new PA staff at a live house, and bands checking their recordings and timing. Works on iPad too.
Listed in
Feedback frequency detection
Lists the bands most likely to feed back, in Hz, from 15 seconds of sound
Real-time spectrum analyzer
50 Hz to 18 kHz, about 23 redraws per second, red line on ringing tones
Stereo recording and video
No compressor or limiter; video with stereo sound in the Full version
Band Timing Check
Per-song target tempo, rushing and dragging, PDF export (Full version)
Daily Ear Training
Same 10 questions worldwide each day, Game Center ranking (free)
Metronome and tuner
Metronome with beat-1 accent; tuner that plays notes as sine tones
Check1.2 tells you, in Hz, which frequencies are most likely to feed back before the show, using only the iPhone microphone. You get a number and a word, like "about 250 Hz (muddy)", plus what to do next. No measuring instrument or external microphone is needed, and everything stays on your iPhone.
Most analyzer apps show a spectrum and leave the judgment to you. Check1.2 lists the bands most likely to feed back and marks ringing tones with a red line while telling musical notes apart by their harmonics. It also records in stereo without a compressor or limiter, and adds Band Timing Check and video for bands. Free to start; the Full version is a one-time purchase, not a subscription.
People learning PA, people doing the PA on the day at a small venue with no dedicated engineer, people training new PA staff at a live house, and bands who want to check their recordings and timing.
Before a show you often cannot tell which frequency to pull down. Check1.2 was made by an independent developer in Japan who works in live sound and mixing, to show those frequencies as numbers anyone on the crew can read, with nothing more than an iPhone.
We have collected here some useful links to help you find out if Check1.2 is good.
Check the traffic stats of Check1.2 on SimilarWeb. The key metrics to look for are: monthly visits, average visit duration, pages per visit, and traffic by country. Moreoever, check the traffic sources. For example "Direct" traffic is a good sign.
Check the "Domain Rating" of Check1.2 on Ahrefs. The domain rating is a measure of the strength of a website's backlink profile on a scale from 0 to 100. It shows the strength of Check1.2's backlink profile compared to the other websites. In most cases a domain rating of 60+ is considered good and 70+ is considered very good.
Check the "Domain Authority" of Check1.2 on MOZ. A website's domain authority (DA) is a search engine ranking score that predicts how well a website will rank on search engine result pages (SERPs). It is based on a 100-point logarithmic scale, with higher scores corresponding to a greater likelihood of ranking. This is another useful metric to check if a website is good.
The latest comments about Check1.2 on Reddit. This can help you find out how popualr the product is and what people think about it.
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