In "The Madness: Memoir of a Piano Tuner" - discussed earlier in this forum, I think he spoke of tuning two pianos for concerts. (Amazon doesn't let you Search Inside this, and I'm too lazy to go thumbing through it.) Anyway, as I recall, he tuned one, and then tuned the second to the first - note by note. Does that work? Is it common practice? I started wondering about this again, last night, watching a two piano concert. One was a NY model D, the other a Yamaha. So - two different scales. How is this generally handled?

Analog method: First tune both pianos as usual. Then compare note by note to determine any discrepancies. If any, make any needed compromises between the two.

Digital method: Tune one according to ones preferred scale and stretch parameters, then use the exact same blueprint for the other, regardless of its scale differences.

Pwg

Answer not really relevant to the concert pianos. But I have four upright pianos. I frequently play one with the left hand and one with the right. The differences in tonal quality, stretch and tuning make for a much richer sound for some types of music IMHO.

Greetings,
Aural approach for us was to tune a temperament on the larger piano, then, via by a shared-thirds testing, match the other piano to the first. Then,completely tune the larger one and then, octave by octave, making sure the second stayed acceptable..

By machine, (much more accurate), compare the two "templates", ( accutuner= FAC numbers). If there are any great deviations in the amount of stretch showing, it is easy to meld the two, or alter one to fit the other. It is also easy to test the matching algorithm, tune a few octaves as indicated and listen. The ear is the quickest way to know where you might need to compromise, but having the information to frame the problem is helpful.
The Sanderson machines have a simple button that will compress or expand whatever octave width the particular program you are using is built upon. Makes it very useful for special purpose tuning, (recording studios, concerti performances..).

I was trained as an aural tuner, by the best teacher in at least the U.S., and the machines have vastly improved both my pitch changes and matching two pianos together. It was not uncommon, at the university, to have to tune two D's in separate spaces, and then let them meet that evening for the performance. When ET at 440 was a necessity, getting the piano microphone-ready, (polished unisons), from 10 cents flat in 90 minutes was a straight-forward job, and it worked every time. Hard to beat the memory and consistency of an ETD in those situations.
Regards,

Thanks, all, for the replies.

That is definitely one job where an ETD can come in handy (as well as the knowledge of how to use it).

Pwg