Tension Difference between 435cps and 440cps

[Joseph Garrett]

List,
Years ago, I calculated the difference between 435cps and 440cps. The
average difference was approx. 5 lbs per string. I'll let you do the math.
Most "plates" are way over-engineered. However, there are those who designed
within a "gnat's eyebrow", so caution is always advisable. Hope this helps.
While we're on the subject of pitch, I personally have not been able to
ascertain WHEN "International Pitch" was established or even who did
establish it. There doesn't seem to be any documentation regarding this
pitch establishment. If any one out there knows, please post it for all to
see.
Regarding Square Grand tuning pitches, etc., if you are tuning one with the
original strings, it is best to use 435cps as a standard. As these
instruments should NEVER be used for students, the pitch difference is of no
consequence. I should say that all instruments of this kind should be tuned
to their "designed pitch", as they will be more stable and the chance of
structural damage is lessened. If you are "restringing" one of these
instruments, you should ALWAYS evaluate the scale using 435cps, (or other
standard, such as 425cps for instruments that are pre-1870's), then reset
the pitch standard to 440cps and "rescale" appropriately, keeping all
tensions within the "original scale" plan. As I have done a lot of this sort
of things over the past 28 years, I will be happy to counsel anyone who is
interested. Also, I do "Scaling" service.
regards,
Joe Garrett, Oregon