pitch raising (longish)

[Mitch Kiel]

   Pitch raises. I love 'em because pianos sound so much better afterwards that customers go gaga.

   For over a decade, I tuned solely by ear and, imho, got pretty good at aural pitch raising. (For this discussion, let's assume our piano is flat and we're raising its pitch to A440. Pitch lowering is no different than pitch raising, just less common.) When I started using visual tuning devices (VTDs), first the Sanderson Accu-Tuner (SAT) and now Reyburn CyberTuner (RCT), my pitch raises improved dramatically. In my opinion there's no contest ‹ after your first pitch raise with a VTD, you'll never want to go back.
   When I'm pressed for time, I can do real decent pitch raises of up to 8 cents with one pass and some touchup in less than 30 minutes. But usually I take an hour and a half to go over the piano twice (or more), and leave a tuning as clean and stable as most standard tunings. 
   
   (Full disclosure: I am a Reyburn CyberTuner dealer and authored its user manual. But I'm here to participate in PianoTech's ongoing conversation, not to grub for spare change. I'll try to follow the examples of list luminaries such as Del Fandrich, Don Mannino, Gayle Mair, and others who grace PianoTech with their objective insights and have the manners to pursue their bottom lines elsewhere.)

Why are VTDs better at pitch raising than aural-only methods?

1. Aural pitch raisers are shooting at a moving target but for VTDs the target stands still.
    Aural pitch raises usually begin with tuning A4 with 25% to 33% overshoot, rough-tuning a temperament, then tuning the other notes with even more overshoot. Problematically,  the temperament is falling *while* other notes are being tuned to it. Hence the "moving target." 
    VTDs use a "virtual" tuning for a target. In other words, VTDs create a page (SAT) or a tuning record (RCT) which is a set of numbers (actually, cents deviation from theoretical equal temperament at a specified partial). These numbers exist in the VTD's computer memory as information. They have no physicality and remain unchanged despite what may happen to the "physical" piano.

2. With VTDs you can tune from A0 to C8 tuning unisons as you go, which as Dr. Sanderson noted years ago is the best procedure for pitch raising.
    Why? Because it gets "pre-drop" out of the way as soon as possible. Pre-drop is the lowering in pitch of a string as its nearby strings are raised but before the string itself is tuned. Post-drop is the lowering in pitch of a string after its neighbors are tuned. 
    (I remember a 100 cent VTD pitch raise where A4 pre-dropped 36 cents. Post-drop was about 6 cents.)
    Pre- and post-drop vary from note to note, depending on string length and diameter, proximity to the flexible portion of the soundboard (usually but not necessarily the center) or bridge (end, apron), etc. They also vary with a piano's design, such as soundboard stiffness (which is affected by string downforce and hence pitch).
   BTW, pre-drop happens even within a 3-string unison during fine tuning. Change the pitch of two outside strings more than a few cents and the center string will pre-drop 5 or 10%. Another VDT advantage...
    
3. A VTD can measure and calculate much more precisely than us puny humans.
    Typically, a VTD measures the "original pitch" of a string, subtracts the original pitch from the target pitch to get the "offset," multiplies the offset by an overshoot percentage to get "overshoot cents," adds the overshoot cents to the target pitch, then resets its display. And all to an accuracy of 0.1 or even 0.01 cent.
   FYI, here's how Reyburn CyberTuner does it:
   RCT automatically measures each note and uses an overshoot percentage best suited for that note, derived from readings taken from over a hundred pitch raises on a wide variety of pianos and out-of-tunenesses. RCT's overshoot percentages range from 4% to 12% in the bass, jump to 35% for the lowest plain wire note (read Bill Clayton's past Journal article to find out why), taper to 27% at C5, increase gradually to 38% at C7, then taper down to 23% at C8. (The actual percentages are more precisely defined. I'd be happy to email this chart to anyone interested.) Even though these percentages are optimized for tuning from A0 to C8, experienced aural pitch raisers instinctively use similarly varying overshoots.
    When pitch raising, RCT also averages the differential (target pitch minus actual pitch) of the note being tuned with the differentials of the previous 5 notes. This helps compensate for single notes with anomalous pitches. (IOW, one note may be much more ‹ or less ‹ off pitch than the surrounding notes.) Why does this help? Because pre- and post-drop is a *neighborly* affair.

    Mitch Kiel, RPT

  PS   I'm not saying that great aural pitch raises are impossible nor that *you* aren't expert at them.
          I'm *certainly* not saying that VTDs are good and aural tuners are bad. In fact both are wonderful and deserve each other deeply. But that's another discussion...