Problem keys detected: 45
| Calculated* avg | Calculated* std dev | KMD avg | KMD std dev | KMD â calculated | |
|---|---|---|---|---|---|
| Downweight (DW) | 57.7g | 3.3g | 60.3g | 5.8g | +2.6g |
| Upweight (UW) | 28.8g | 4.0g | 32.7g | 5.8g | +3.8g |
| Balance weight (BW) | 43.3g | 2.4g | 46.5g | 5.1g | +3.2g |
| Friction (F) | 14.5g | 2.8g | 13.8g | 2.8g | -0.6g |
Best-fit downweight line:
On a well-regulated piano, downweight falls slightly from bass to treble. The best-fit line shows that fall; the scatter is the std dev of each key's downweight from the line, so the smaller it is, the more even the regulation.
* Calculated here from the measured curves, using the travel just before each key's damper lifts (DW*, UW*, BW*, F*). Keys without a damper lift use the KMD's values.
| Avg | Std dev | Keys with data | |
|---|---|---|---|
| Key travel, all keys | 10.03mm | 0.30mm | |
| Naturals | 9.89mm | 0.24mm | 52 |
| Sharps | 10.29mm | 0.20mm | 36 |
| Avg | Std dev | |
|---|---|---|
| Set-off, all keys | 8.13mm | 0.34mm |
| Set-off, naturals | 7.96mm | 0.23mm |
| Set-off, sharps | 8.38mm | 0.31mm |
| Aftertouch, all keys | 1.70mm | 0.33mm |
| Aftertouch, naturals | 1.71mm | 0.33mm |
| Aftertouch, sharps | 1.68mm | 0.33mm |
| Avg | Std dev | |
|---|---|---|
| Lift position, all keys | 3.82mm | 0.46mm |
| Lift position, naturals | 3.86mm | 0.49mm |
| Lift position, sharps | 3.76mm | 0.42mm |
| Damper weight | 23.0g | |
| Damper weight, scatter about trend line | 4.0g |
Damper weight is expected to fall steadily up the keyboard. A straight line fitted across the damper keys falls by 0.15g per key. The scatter is the std dev of each key's damper weight from that line: the smaller it is, the smoother the taper.
These interactive dot plots show key measurements across the entire keyboard. Hover over any dot to see the note name and exact value.
The friction, downweight and balance weight plots can show the values reported by the KMD (averaged over 2–4mm of travel), our calculated values (F*, DW* and BW*), or both. Keys tinted red have a damper lifting before 4mm, which skews the KMD values. For keys with a damper lift, we average from 2mm before the lift up to just before it, never using readings below 1mm. A hollow dot marks a window under 0.5mm wide, which has few readings. All other keys keep the KMD values.
Best-fit downweight line:
On a well-regulated piano, downweight falls slightly from bass to treble. The best-fit line shows that fall; the scatter is the std dev of each key's downweight from the line, so the smaller it is, the more even the regulation.
| Note | Key # | Problems |
|---|---|---|
| A0 | #1 | Low balance weight (BW*): 38.4g (<38.4g) Damper weight significantly different from a neighbour: 29.0g vs 22.0g on A#0 |
| A#0 | #2 | Damper weight significantly different from a neighbour: 22.0g vs 29.0g on A0 |
| C1 | #4 | Damper weight significantly different from a neighbour: 27.0g vs 35.3g on C#1 |
| C#1 | #5 | Damper weight significantly different from a neighbour: 35.3g vs 27.0g on C1 |
| D1 | #6 | Shallow dip: 9.23mm (<9.43mm) |
| E1 | #8 | Damper weight significantly different from a neighbour: 22.6g vs 31.2g on F1 |
| F1 | #9 | High downweight (DW*): 68.9g (>64.4g) High friction (F*): 21.6g (>20.0g) Damper weight significantly different from a neighbour: 31.2g vs 22.6g on E1 Damper weight significantly different from a neighbour: 31.2g vs 19.4g on F#1 |
| F#1 | #10 | Damper weight significantly different from a neighbour: 19.4g vs 31.2g on F1 |
| G#1 | #12 | Low upweight (UW*): 19.9g (<20.8g) |
| A1 | #13 | Low upweight (UW*): 19.8g (<20.8g) High friction (F*): 20.0g (>20.0g) |
| B1 | #15 | Low upweight (UW*): 20.3g (<20.8g) High friction (F*): 21.0g (>20.0g) Damper weight significantly different from a neighbour: 20.9g vs 32.4g on C2 |
| C2 | #16 | Damper weight significantly different from a neighbour: 32.4g vs 20.9g on B1 |
| C#2 | #17 | Damper weight significantly different from a neighbour: 33.2g vs 22.2g on D2 |
| D2 | #18 | Damper weight significantly different from a neighbour: 22.2g vs 33.2g on C#2 Damper weight significantly different from a neighbour: 22.2g vs 33.3g on D#2 |
| D#2 | #19 | Damper weight significantly different from a neighbour: 33.3g vs 22.2g on D2 Damper weight significantly different from a neighbour: 33.3g vs 26.7g on E2 |
| E2 | #20 | Damper weight significantly different from a neighbour: 26.7g vs 33.3g on D#2 Damper weight significantly different from a neighbour: 26.7g vs 19.1g on F2 |
| F2 | #21 | Damper weight significantly different from a neighbour: 19.1g vs 26.7g on E2 Damper weight significantly different from a neighbour: 19.1g vs 26.0g on F#2 |
| F#2 | #22 | Damper weight significantly different from a neighbour: 26.0g vs 19.1g on F2 |
| G2 | #23 | Damper weight significantly different from a neighbour: 21.6g vs 33.6g on G#2 |
| G#2 | #24 | Damper weight significantly different from a neighbour: 33.6g vs 21.6g on G2 Damper weight significantly different from a neighbour: 33.6g vs 22.9g on A2 |
| A2 | #25 | Damper weight significantly different from a neighbour: 22.9g vs 33.6g on G#2 |
| A#2 | #26 | Early damper lift: 3.13mm (<3.2mm) |
| B2 | #27 | Shallow dip: 9.31mm (<9.43mm) |
| C3 | #28 | Early damper lift: 2.68mm (<3.2mm) Damper weight significantly different from a neighbour: 18.0g vs 32.4g on C#3 |
| C#3 | #29 | Deep dip: 10.66mm (>10.63mm) Early damper lift: 3.16mm (<3.2mm) Damper weight significantly different from a neighbour: 32.4g vs 18.0g on C3 |
| D#3 | #31 | Damper weight significantly different from a neighbour: 34.6g vs 21.9g on E3 |
| E3 | #32 | Low aftertouch: 0.94mm (<1.04mm) Damper weight significantly different from a neighbour: 21.9g vs 34.6g on D#3 |
| F3 | #33 | Damper weight significantly different from a neighbour: 25.9g vs 18.1g on F#3 |
| F#3 | #34 | Damper weight significantly different from a neighbour: 18.1g vs 25.9g on F3 |
| D4 | #42 | Early damper lift: 3.10mm (<3.2mm) |
| E4 | #44 | Early damper lift: 2.76mm (<3.2mm) |
| F4 | #45 | High balance weight (BW*): 48.4g (>48.1g) |
| G4 | #47 | Early damper lift: 3.20mm (<3.2mm) |
| G#4 | #48 | Early damper lift: 3.13mm (<3.2mm) |
| A4 | #49 | Early damper lift: 3.18mm (<3.2mm) Damper weight significantly different from a neighbour: 17.5g vs 23.8g on A#4 |
| A#4 | #50 | Early damper lift: 2.87mm (<3.2mm) Damper weight significantly different from a neighbour: 23.8g vs 17.5g on A4 Damper weight significantly different from a neighbour: 23.8g vs 16.6g on B4 |
| B4 | #51 | Damper weight significantly different from a neighbour: 16.6g vs 23.8g on A#4 Damper weight significantly different from a neighbour: 16.6g vs 25.3g on C5 |
| C5 | #52 | Damper weight significantly different from a neighbour: 25.3g vs 16.6g on B4 Damper weight significantly different from a neighbour: 25.3g vs 18.4g on C#5 |
| C#5 | #53 | Damper weight significantly different from a neighbour: 18.4g vs 25.3g on C5 |
| G#5 | #60 | Low aftertouch: 0.63mm (<1.04mm) Late set-off: 9.68mm (>8.81mm) |
| E6 | #68 | High downweight (DW*): 64.4g (>64.4g) High friction (F*): 21.3g (>20.0g) |
| F6 | #69 | High downweight (DW*): 68.1g (>64.4g) Low upweight (UW*): 14.0g (<20.8g) High friction (F*): 27.1g (>20.0g) |
| A7 | #85 | High aftertouch: 2.41mm (>2.35mm) Early set-off: 7.44mm (<7.46mm) |
| B7 | #87 | High upweight (UW*): 37.8g (>36.8g) High aftertouch: 2.66mm (>2.35mm) Early set-off: 7.36mm (<7.46mm) |
| C8 | #88 | High upweight (UW*): 38.5g (>36.8g) High balance weight (BW*): 49.1g (>48.1g) |
Interactive Visualization: Use the slider below to explore the touchweight curve for any key on the piano.
This interactive plot shows all downweight curves (key press down) across the entire keyboard with a color spectrum from red (bass) to violet (treble). Use the slider below to highlight individual keys and see their curves in context with all others.
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