Updated for iPhone X
Ratings and Reviews
This app is wonderful in concept, but a disappointment in actuality. I tried it on several watches, and could only get it to register a signal on one--and even that one was hit and miss. I ran the app on an iPhone 5, and found it frequently crashed. Whether that is a problem on other platforms, I don't know. Unlike another reviewer, I found the developer to be responsive and eager to help me get the app to work. But I'm not looking for a relationship with a developer: I just want an app that works so I never have to wonder how good the support is. Kello is not that app. To balance this negative review, I add that I was so favorably impressed by the developer, that I would consider purchasing a later version if he could assure me the deficiencies had been corrected.
This latest revision of the software seems to improve the ability to "lock on" to the mechanical signal a great deal. Even some quiet watches which could not be tracked with the case back closed can now be tracked simply by placing the microphone next to the case back. There is still a lot of drift as the program tries to interpolate the accuracy of the timepiece, but even this seems improved. I don't know if it is possible using the stock DSP plugins in the developer package and the stock microphone, but the ability to sense a beat error would be really really nice. For minor adjustments to the regulator this is very helpful, and with the update the efficiency is improved. If beat cannot be assessed with this technology I would be very happy just to have a system that locks on more quickly and gives a more stable instantaneous accuracy value. But this version is certainly worth the asking price, as it has saved me considerable time as compared to my previous technique of checking fine regulator adjustments using a clock.
Works after finding sweet spot.
At first I could not figure out how to get it to read, I put the microphone of my iPhone 5s on every side of the watch but only was able to get a reading when I put my phone standing up on top of the face of the watch. It only took me 10 minutes of reading and adjusting to get to run within one second for 24 hours. I am setting a Seiko 5 with a 4R36 movement and after 18 hours it is off by a half second. It is best to hack and stop the heart and restart it, it seems to pick up the adjustment better, otherwise it will show a algorithm of fast and slow for 10+ minutes and narrowing to settle in every wave up and down in speed. This is normal. It might be a good idea to let it sit for 30 minutes after adjustment to re read to get a more accurate reading. It is expensive but much cheaper than a real watch regulator and saves the guessing.
With Family Sharing set up, up to six family members can use this app.