Tuning a grand yesterday, I got to watching the bass bichords as I pulled the unisons in. Out of tune by a beat or so, with each hammer impact the visible reaction of the strings was quite different. One string would leap up quite a ways on one blow, while the other would go higher on the next, and they would react similarly on the third. The closer to clean the unison got, the less the visible difference in the string reactions until they were visually identical blow after blow as the unison tuning became acceptable. Yea, I know why, but it is still interesting to watch the effect of the phase difference on the string excursion at hammer impact. Hardly a visual tuning aid, but I thought it was kind of cool to play with. Ron N
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