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Hello Piano Tuners-
I have been using TuneLab for the ipad for a year now, and would like to start taking full advantage of this program. The tuner who taught me tuned all by ear, so he is no help in using TuneLab. The TuneLab manual freely uses some terms that I am not familiar with. Are there any tuners on this forum interested in elaborating on some terms from the manual? Particularly, I could use a clearer definition and explanation of the following terms:
Stretch
Inharmonicity Constant
Tuning Curve
Deviation Curve
Or, could anyone recommend a book which clearly explains more of the theory behind tuning pianos with a digital device?
Thanks,
Michael

You and me both. Got TuneLab about a month ago also with the ipad.
I had problems doing a tuning and my treble sounded flat by using TuneLab...
I posted a thread... Aural vs electronic tuning... And got an overwhelming response!!!
I have been tuning pianos for roughly 15 years now and was also trained aurally.
If you give the post a read I'm sure it'll help you a lot as it has done me.
For one, Mr. Robert Scott, the programmer of TuneLab helped sort out my flat treble problem. All I had to do was to change the ratio in the tuning curve settings from 4:1 to 4:2 in the treble. I assume this is related to the stretch, which I gather is the amount one wants to expand octaves either in the treble or in the bass...
After that, the tuning, according to my ear... Sounded better.
This is piano dependent though. Today I tuned a Suzuki Upright that I had "over-pulled" using the over-pull on TuneLab about 3weeks ago. When I did the raising then, I was mistrusting of the over-pull on TuneLab as it sounded very strange indeed. Today, however, I was pleasantly suprised to find the piano on pitch after it had been raised by 70cents. It is a modern piano and the tuning pins are tight and spongy, so I was expecting the worse. Happily I was not.
I set TuneLab up to calculate the inharmonicity measurements and saved them.
I also don't only take one measurement, but elect to use the "save+" instead of just "save" and measure another 2 of each note. I use the C's... C1-C7...(I add the C7 just for a little extra).
When I came to my treble break, my tuning curve settings for stretch, the 4:1-4:2 change I made was saved to default and my treble started to sound sharp.
I don't know if I'm altogether doing or saying it right, but I changed it back to 4:1 and the piano sounds fantastic now. The tuning after the raise was merely a touch up.
I also have found a nifty way of setting customized offsets... If you don't know already.
When at the treble break (the bass and mid sound always fine to me using TuneLab), I check my first and second unison octaves to what suits my ear and adjust the offset by running my finger over the phase display until the octave registers on the red line, indicating it is on. From there my tuning ends up being exactly what I want.
I'm finding TuneLab truly a help with my work.
It brings for me the two worlds together... Aural and electronic. Where the one fails or is perhaps too tired, the other can take over. A back up of sorts.
Well, that's my story with TuneLab and am looking forward to learning more.
If you can help in these regards, please get hold of me!
Thanks in advance.

Remember, Tunelab is simply one more tool at our disposal. Tunelab is invaluable to me for overpulls and 1st pass temperament - but no ETD is perfect. I always verify aurally what Tunelab is telling me - I'd do that with any ETD. For example, a pre Baldwin Wurlitzer console with dubious scaling fooled Tunelab into a temperament my ears told me was not optimal. So I corrected the temperament aurally, and tuned aurally. No big deal. That piano was a 30 cent pitch raise 6 months ago, and it was still spot on pitch! Last week, a Steinway O told me it needed more treble stretch than Tunelab was calling for, so I compensated by ear. On many tunings, no compensation is needed. It all depends.

When tuning with any ETD, trust, but verify, and fix by ear if needed!

On Tunelab overpulls, I pull up a pre recorded tuning file of a similar piano and load that before measuring for the overpull. I don't know if that is more accurate, but since the tuning file is displayed, I'm sure it helps. I wouldn't want to overpull a spinet piano when the file of a Steinway D is loaded.

Hi Michael!

Stretch - The difference required of a musical tuning to make the same named notes sound "good" - as opposed to a simple doubling of the frequency of the octaves. You might think that A 440 would perfectly match up with the octave below at 220 or the octave above at 880..

BUT, there's this inharmonicity thing. In tunelab, while you use the measure function, it displays numbers for a bunch of partials. (many times the first partial is missing) Those numbers represent the cents away from a simple math multiplication that that single string vibrates. Even though we may hear "C", that string actually sounds:
C, C+ 1 octave, C + 1 octave + 5th, C + double octave... (look up partial series of a vibrating string)

SO, those numbers you got in tunelab displaying the difference of the specific partials... The progression of the numbers for that single string gets represented by the fudge factor called the inharmonicity constant - a single number that is a multiplier that allows one to predict the location of other partials of one string based on knowing the location of one partial.

And all of this is important to predict the stretch - the musical "good" sounding of a single or double or triple octave. The machines can't hear "good", so they try and line up matching partials from multiple notes to come up with a solution. (Using inharmonicity constant to manipulate the tuning curve)

Ah, the tuning curve... It is the plotting of the difference in cents from the simple math doubling of the octaves - showing each note of the piano - Above the middle, notes are plotted sharp, below flat to try and make a musical "good" blend of the octaves. Notice I'm not even talking about temperament yet!

In the tuning curve display, look in the middle. There is an octave that is nearly a straight line representing the temperament - everything else is calculated from these notes using the preferences for certain partial matches, or single or double octaves, or octave + 5ths....

Not sure about the Deviation curve - I could hazard a guess, but I'll have to go look in tunelab to see what's being referenced.

Hope that helps!

Ron Koval

Thanks folks,
I am digging through the Aural vs. electronic tuning thread right now. Nice youtube channel Ron, thanks for posting that stuff.
Michael