I went back and re-tuned my Fazioli F308 to ensure that unmuted unisons as an ensemble did two things:
1) Hit the Freeze indicator to within 0.2-cent
2) Slow wobbles (as seen in the red indicator and heard audibly) should be minimal coming off the attack. The wobbles are not to be confused with the natural decay in pitch (as amplitude decays off the attack) which occurs in all pianos, especially in the mid and upper registers. This is not the wobble but the FM decay as amplitude decays. I tune out the wobble by taking the single string that moves the most coming off the attack and over compensate for it by stretching its tuning a 0.2-0.3 cents in the opposite direction of the wobble range. This usually works well. If that does not do the trick, then I check string leveling for any phasing that may be happening. I also check any string termination issues at the bridge and A-graf. This is well worth the time spent to get the most stable unisons possible.
I then play parallel 12ths through the whole range, esp. low-mid and mid-upper, and listened for a beatless clean sound that is clear and brilliant on the attack and sustains well as both amplitude and pitch decay. I was able to find one 12th which I perceived as just a little bit less than perfect, and it led me to one of the 6 six strings that was just a little off by a few tenths of a cent. This '12th Test' is what I call it, and it is a really great 'acid test' of achieving near perfection.
Then I played the ‘chorale’ section of the Chopin Nocturne Op. 48 / No. 1. It is full of a very rich ensemble of chord combinations and some of which greatly expose anything that is even the slightest bit off in the piano.
