dialtone and Tunelab

[Tom Cole]

Robert Scott wrote:
> 
> Years ago I researched the dialtone as a frequency standard.  What
> I found out was that although it may appear to be very close to
> A-440, it is not guaranteed.  And each central office has their
> own dialtone generator. 

Right. It's called a ringing and tone plant. Most cities have the "new"
dial tone (F and A) but not all.

I just measured the local A and found it dead on at 440.00 according to
RCT. The F, however, is 3 cents sharp (no Reverse Well in Santa Cruz).

> So, the bottom line is that I would trust a good
> tuning fork at a known temperature more than I would trust the
> dialtone as a pitch reference.

Okay but there are those battlefield situations where you are out of
town without your tools, a piano needs to be tuned and only a tuning
wrench is available. If that sounds far fetched, just such a thing
happened to me last June in Yonkers, NY. And, yes, I picked up the phone
for a pitch reference.

Tom Cole, erstwhile Western Electric installer