Soft blows

[Ron Nossaman]

>Doesn't the need for hard blows vary with the scale design? Seems to me that
>some pianos would be impossible to tune with stability without employing
>hard test blows.

I agree. Only I wouldn't say some pianos. I'd say most (maybe all) pianos 
under some conditions.


>The "bump-up-bump-down" is what I trust.

Likewise, but a firm rap somewhere in the process is a necessity. In my 
experience, it's simplistic and unrealistic to assume that all the string 
movements determining tuning stability (not out of the control of the 
tuner, like temperature and humidity fluctuations) happen from the bridge 
forward (or up), and are controllable with hammer technique and soft blows.


>Ten years ago I measured the side view of note C5 on a Steinway Band
>the maximum vertical displacement on that note caused a hard blow,
>and fellow NH chapter member Doug Kirkwood and I calculated the
>string friction barrier at the capo and the momentary tension spike
>of a test blow. 21 lbs vs. 3.5 ounces respectively, as I remember. I
>invite someone else to run this calculation.

I've done some of this. The 21 lbs is about right at the capo with 15° 
counter bearing angle. It will be about 14 lbs at 10°. The test blow 
tension spike needs more information. What pitch, wire diameter, 
approximate strike point, and maximum deflection at impact?


>As Don says, the more wire you move the better an insurance policy
>the test blow is.

Absolutely. It comes down to tension differences between string sections - 
which we can't measure directly. We can only observe the pitch change when 
strings render past bearing points and the observable pitch of the speaking 
length changes. And it doesn't have to be the tuner moving the wire with 
the tuning hammer to make this happen. Many times, I have heard an 
un-touched string drop considerably in pitch with a (one) firm test blow, 
when a soft blow had indicated it was very close to right in pitch. In a 
perfect world where the temperature and humidity don't fluctuate and piano 
strings don't go out of tune more than a couple of cents either direction 
between tunings, sure, soft blow tuning can work. In my world, where the 
string may have been over 20 cents in either direction between the last 
tuning and now (regardless of where it is now), if it isn't hit firmly at 
least once, it isn't trustworthy, no matter how expert the tuner thinks his 
hammer technique is, because the change doesn't necessarily come from this 
side of the bridge. You don't know where it's been.


Ron N