As a watch enthusiast one is always anxious to know exactly about the technical details of his jewelry pieces. This also includes measured values for accuracy, which ideally lie within the tolerance of the movement. Now one has the possibility to collect experience values over several days – which corresponds to the normal case. Or to rely on technical aids such as a timegrapher, which accelerates the evaluation of the movement tremendously.
A timegrapher records the noise emission of the movement (the escapement) with a microphone attached to the case of the watch and evaluates the time intervals in which the ticks occur against a reference time signal. In addition to the rate deviation, shown in “+/- X sec/day”, some models also evaluate anomalies of the balance or the gear train or display them graphically.
Unfortunately, real timescales are only worthwhile for very ambitious watch lovers. So it is obvious to get an overview of the accuracy with other tools.
Theoretically every smartphone combines all requirements to pack the functionality of a timer into an app.
I want to tell you something about my impression of the iOS app “Kello”.
According to the instructions, the app only needs the microphone of the included iPhone headset as input source for timing.
Unfortunately, when measuring my watches, I had to come to the conclusion that the values determined are far removed from my everyday experience and that the app therefore has no added value for me.
But now you have to consider that the gear behavior of a watch can differ massively from the respective situation. For example, a watch can run in positive while it is in motion when worn in negative. The temperature also has an influence on the gear.
But now I know the behaviour of some of my watches in the cool watch box and even with these models the app doesn’t come close to my expected values.
- at night: -2Sec/day
- day in move: -4Sec/day
- in the middle: -3sec/day
- Value determined by Kello in peace: +0,3Sec/day
- at night: +8Sec/day
- day in move: +5Sec/day
- in the middle: +7Sec/day
- Value determined by Kello in peace: +25Sec/day til ∞
Especially at the Junkers Bauhaus and some other watches measured by me I notice that the value determined by Kello shifts more and more in one direction with increasing time. So the app may show a gear of +10Sec. for a few seconds at the beginning, but then it increases to +90Sec and more during the rest of the measurement. The measurement is extremely off track.
In contrast to a dedicated timer, neither the developers nor I have any influence on the exact behavior of the app on a smartphone. I can well imagine that the app also provides exact values for some users. There are enough videos on Youtube for this, but maybe components within the iPhone or the headset have changed so much in the course of time that the signal acquisition and processing no longer work properly with the new hardware.
It remains for me to continue to measure the accuracy of my watches throughout the day and to gain long-term experience. But I like the idea very much and I am curious if there will not be a more sophisticated way to measure watches with the help of a smartphone in the future.