http://PianoSens.com There are many conceptual errors piano tuners make with 'fast re-attack' piano tuning. It produces ‘convolutional errors’ of overlapping the past waveforms with the new ones, and the prior ones have transients that are not settled and drifting rapidly. The underlying algorithms of an ETD use Fourier Transforms that rely in the principle of 'a window of time' frequency analysis during that time interval. When you use fast re-attacks, you destroy this principle and will never get it right due to overlapping transients that have not settled. My research shows that you need is maybe a quarter-second of ’time space’ where you lift off (letting the damper dampen the string quickly) and then re-attack. The procedure is to hold the attack down for about 1 second and use the continuous indicator of he ETD while moving the tuning hammer during this 1 second holding interval, then let off for a very brief quarter-second, and re-attack. If you do this, you will get amazingly better results. Also, don’t ‘dwell’ on the note for more than 1.5 sec, because the note is rapidly drifting (flat). If you tune to that late time, you will have your note be way too flat on the first second of the attack where the maximum power is. It does matter!