CAUT

I will remove the whole top section at a time with no concern and string that up first. Then, if you want to do the next section down, I have usually done 1/2 of it a time.  I have not removed that whole lower treble section at once with the rest of the piano at pitch, just to be safe.  If there is an official factory recommendation on this that would be interesting.   

best,

Dennis Johnson

I restrung two Steinway Bs this past month, and decided to do some experimenting while lowering tension. First, I thought I'd just do individual strings, and chose C4 to B4 to look at. I checked pitch initially, and it was quite close, so I could just read off the tuning I had stored for them as a reference.

I removed tension from F4, and saw the usual effect of most sharp closest, tapering out, about 5¢ down to 2¢ within that octave. I did some other strings (F4, D#4, G4, E4, in that order) within that octave, and found increasing sharpness in the same pattern. Not very illuminating, but after I had released those four strings in the middle, I had sharpness of 10¢ at the extremes (C4 and B4) and 15 - 18¢ in the middle).

I decided to lower the bass strings and see what happened (I've replaced just bass strings many times, and seen a rise of about 25¢ in the tenor, which goes back when the new strings are pulled to tension). The result was pretty predictable, as the octave 4 strings ended up 25-35¢ sharp.

I then thought, what the heck, I'll live dangerously and lower F2 to E3 and see what happens. WOW! The notes in the octave above (F3 - E4) now jumped (from where they were) to a final of 45 - 60¢ sharp. As long as I was that far in, I decided to go ahead and release F3 - B3. More WOW: the final pitch was now 70¢ (B4) to 97¢ (E4) sharp.

At that point, I decided I had expended as much extra time as I had to spare, and completed the restring.

Second piano, I decided to try just lowering sections, starting with F2 - E3. Following that, I measured two sample notes C4 +29¢, B4 +17¢

Lowered F3 - B3. Results: C4 57¢, F4 54¢, A#4 43¢, E5 30¢.

I dropped the full bass section: C4 70¢, F4 69¢, B4 51¢, C#5 46¢, E5 39¢, C6 27¢, E6 16¢

Lowered C4 to B4: C5 93¢, E5 81¢, A5 72¢, C6 65¢.

Lowered C5 - C7: C#7 139¢, F7 124¢, A7 91¢, C8 58¢

Lowered up to B7: C8 135¢.

No strings broke (low tension scale). No plates broke (hefty Steinway design). The wedge between the horn and the belly fell out in both cases.

So there you have some data to think about. I think it likely that the plate is the main factor, in part because these pianos are over 50 years old, have no crown and next to no down bearing. How much movement of the plate is necessary to cause changes of pitch of this magnitude? I suspect it may be a very tiny, almost unmeasurable amount (without fancy instrumentation), but maybe someone with the needed figures and spreadsheets can tell us.

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This illustrates why Rick Florence's Bosey popped strings - high tension scale. There is some shifting going on, probably very minimal in terms of the plate, but that tiny amount is enough to change string tension dramatically and pop strings if they are closing to breaking point.