On Wed, Aug 5, 2009 at 5:23 PM, PianoForteTechnologies < pianofortetechnology at saol.com> wrote: > I am at the moment only an aural tuner, due to etd’s being extremely > expensive for a South African with regards to the exchange rate, but that’s > my problem, could you explain in aural terminology and could you explain at > what point the strings become overstretched? How many semitones can one > overpull without the strings being overstretched? > The "standard" answer for how much overpull is about 30% in the midrange, 20-25% in the bass, and 33% in the treble, but tapering down to 25-30% in the topmost notes. A 200 cent pitch raise to A442? You can't safely use a 30% overpull in this case as that would be 60 cents above pitch. So, set A4 about 20 cents above your pitch source for your first pass. If you're using a a fork, that would be about 5 beats per second sharp of the fork. However, you should first determine if the piano is structurally sound before doing the pitch raise. For this reason, many tuners would start by tuning A4 to A442 (not going higher than that) on the first pass. By the time you finish, you'll know if strings will break, or if the plate has cracked. <slight grin> Seriously, you might be dealing with a piano that can't be tuned at A442 for various reasons: wasn't designed to be tuned there, the plate could be cracked, or the pinblock separated from the back, etc. If the structure is solid, it might be a good time to do a "blind" pitch raise first. Find out how much the pin needs to move to get the pitch fairly close to target. Then move the rest similarly, but less in the bass. At least that will get you closer, and it will take just a few minutes to do that. Things are going to change a lot as you add tension. Therefore, set your goal to get closer and closer. I'm an aural tuner, but haven't had a pitch raise that large yet. (The largest so far was about 130 cents.) I'd figure on at least 3 passes and leave it in a musically decent but not finely tuned state. In other words, just get it in the ball park the first session. Then I'd come back in 1-2 weeks and try a fine tuning. But it may well be you'll have to do another small pitch raise the second session. -- JF -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://ptg.org/pipermail/pianotech.php/attachments/20090805/d40d7af2/attachment-0001.htm>
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