>From Jim Coleman, Sr. Since several did not write me personally but requested my notes from the pianotech list, I decided to include the notes here. There may be some application to the use of other ETDs, but none of the others have the convenience of Double Octave Beat control (DOB) on the fly. Custom SAT 3 Tunings Only one inharmonicity sample (A4) is taken. Double Octave Beat (DOB) is used to control the Midrange, Treble and Bass stretch. During classes at PTG Conventions, the author has discovered that the audience preferred melodically stretched triple octaves that are much wider than harmonically stretched octaves. Since melodically stretched triple octaves are intolerable, harmonically speaking, a balance between single, double, and triple octaves is suggested. FAC tunings work just fine for large, well scaled pianos. They are predicated upon the idea that a double octave should have approximately 1/3 beat stretch and that the Bass 6-3 type octave should have a similar stretch. Custom Tuning allows the technician to control the 4-1 Double Octave Beat according to his/her own preferences. The author's preference is to have a balance between the single , double, and triple octaves in the treble section and to have cleaner 6-3 type octaves in the Bass except in large pianos which may tolerate even more stretch than the FAC type.) Here is one way to do it: Turn on SAT 3 then press Tune button TUNE A4 to stop LEDs Change to OCT 6 Press MSR button and Up/Dn Cents buttons to stop LEDs Multiply the value in Cents window by 0.8 to get the resultant Stretch Number Hold down blue SHIFT and touch STO-Stretch to store this Number. Accept the Stretch numbers of F3 = 8.0 and C6 = 6.0 as defaults. (DOB will control this). Press PAGE-Up once to select page 1. Hold down STRETCH, hold down MEM, release STRETCH, release MEM. A complete tuning will be calculated in 5 seconds when A0 appears. Set OCT = A3, Play A4 which was already tuned. If LEDs drift to left, add Double Oct Beat control until the LEDs stop by holding down Blue SHIFT and touching CENTS-Up. Then change Note Up/Dn to make the DOB apply. Repeat this process until the LEDs stop. If you wish to have a half beat stretch in the A3-A4 (4-2) octave relationship, add another 0.5 DOB. This will make the F3-A3 M3rd 1/2 beat slower than the F3-A4 M10th after the A3 is finally tuned. If you wish only a 0.3 difference in the Octave, then add only 0.3 DOB. Tune downward from A4 to the break, making use of aural test intervals like M3rds, P5ths, and M6ths as they become available for ease of tuning. Try to keep the octaves below F3 as 6-3 type octaves on medium sized pianos. After tuning the E3, play previously tuned E4 (set SAT 3 to B5 in TUNE mode and stop LEDs with CENTS buttons). Play E3. If the LEDs are stopped, you have a perfect 6-3 type E3-E4 octave. Use the aural test E3-G3 = G3-E4. The E3-G3 beats will be the same as the G3-E4 beat rate. If the E3-G3 beat rate is slower, then the 6-3 octave relationship is stretched and the LEDs at B5 (Tune mode) will be moving to the left when E3 is played. If this occurs, then possibly the DOB could be reduced gradually at this point. Don't forget to get back into MEM mode after any checking in TUNE mode. It is much easier to do this than to write about it. Tune from A4 to C5 in the original DOB value. After tuning C5, change to C6 temporarily to check how the intervals (octave, double octave, 12ths and 19ths) will come out by the time you get to tuning C6. Ie. when playing C5, C4, F4, and F3. The LEDs will probably be moving to the left while playing octaves or double octaves. the LEDs will probably be moving right or be stationary for the 12ths and 19ths. Try to get a balance between the 12th and the 19th in order to get a reasonable triple octave (C3) unless the single octave C5-C6 will be too wild. Use DOB to accomplish this balance. If in using the 12ths or 19ths, the LEDs are moving right, the 12th or 19th is narrow. If the LEDs are moving left, the 12ths or 19ths are widened. It is usually best if the 12th is widened only slightly and the 19th is narrowed slightly. In most cases this will make the triple octave about right. Tune all notes from C5 through C6 with this DOB setting. After tuning C6 change the Octave to C7 to see how things will be when you finally get to C7. Play C6, C5, C4, F5, F4, to check the single, double, and triple octaves, as well as the 12th and 19th relationships. If balancing out these intervals requires a different DOB, then plan to gradually change DOB through the next octave C6 to C7 to accomplish what the C7 will require for best balance when you get to C7. These settings will accomplish smooth graduations of the 10ths and 17ths, and provide a good balance in the single, double and triple octaves. After tuning C7, change to C8 to see how the current DOB setting will manage the single, double, and triple octave relationships as well as managing the 12ths and 19ths. Again, try to balance out all of these intervals by adjusting DOB gradually in the 7th octave to meet the repquirements of C8 if necessary. Most people can tolerate up to 5 bps in the single octave in this area since the duration of these notes is very short Bass tuning in MEM mode is quite simple. For MEDIUM and SMALL pianos, it is best to maintain pure 6-3 octaves. This can be controlled with DOB by playing the upper (pretuned) note and stopping the LEDs with DOB. If while playing the upper note the LEDs move to the right, you need less DOB or possiby negative DOB to stop the LEDs. Then tune the lower note of the octave to this setting. About every 4 or 5 notes going down the scale you may need to revise the DOB to maintain pure 6-3 type octaves. Bass tuning for larger pianos may sound better with 8-4 type octaves. For example, while tuning C2 to (previously tuned) C3, you could set the SAT3 to F2 (its 6th partial will be displaying C5). Play C3 and stop the LEDs with DOB changes which its 4th partial requires. Play and tune C2 to stop the display with its 8th partial. An aural test for this would be to play C2-G#2 = G#2-C3. 8-4 tuning is usually wider than 6-3 tuning. On very large grands even 10-5 tuning can be used. An example might be in tuning C1 to C2, one could set the SAT 3 to A1 (its 6th partial would be at E4 which is the 10th partial of C1). With either Cents resets or DOB control one can stop the LEDs while playing C2 and then tune C1 to stop the LEDs. The aural test for this would be: C1-A1 = A1-C2. Jim Coleman, Sr.
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