I've used the same system for 20+ years (with special exceptions). Deagan C bar, 523.27. Wonderful clear LOUD tone, the ultimate in stability at room temp, hands free, and the client (esp concert clients) can hear it's dead on as well as you. It impresses a lot of pro pianists who've never seen one, great conversation starter. I'll never use any other pitch reference. Procedure: First rough it in, pound, repeat. The check against beat speed of the piano's C to the tenth below A flat beats, versus the bar's C to the tenth below A flat beats, fine adjust, pound, repeat till satisfied. Super accurate if you hear tenth speeds well. Takes about two seconds for the whole procedure. Just kidding, it takes as long as it takes. Only exception is when tuning to A 441, 442, 444, etc, for Argentinian, Chilean, etc, or European artists, (or just plain weirdos)then I use a semi-cheapo guitar tuner (that does one hertz increments A 430-A 450) that I've made sure is calibrated to my bar first. BTW, I have all three Deagans, a "C", a "B flat", and an "A". Have used all three for fun at different times. You can get them on Ebay once in a while. Just enter "Deagan" in the search. Be patient, they average one up for sale every 6 months.
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