Pianotech

  • 1.  Answer to Tim on Latency

    Posted 07-03-2024 01:45
    • Tim Wrote:

      Thanks for the info.

      I was speaking with a friend today about tuning within the half second and this question came up. With all digital ETDs (that I know of at least), there is a small delay before the pitch goes on display. When milliseconds are of the essence and there is a 250 millisecond (or so) digital delay, how can we be sure that we are tuning within a tight enough window, unless using a stroboscopic tuner?


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      Tim Foster RPT
      New Oxford PA
      (470) 231-6074
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      Tim, 

      You are referring to the latency in the display of a tuning app. I understand that. Here is the solution. The Freeze Window. It allows the user to exactly set the time window length from the hammer strike to the stop point and that is the window length and then the result of the calculations are displayed. 

      In my latest video, How Spatial Position Affects Piano Tuning, link below,

      https://www.youtube.com/watch?v=26zskT_GvkA&t=6s

      I show exactly how a spectrogram is made. You will not need to worry about any latency issues if the app uses and displays the Freeze Window, which is essentially the tuning result from first FFT block calculation. In this example it is from the point in time near the hammer strike to the end of the block time thereafter. The samples of sound that are captured during that block of time are used in the calculation. You then see the tuning result from that block. How far off it is from zero is then used to re-strike the hammer until iteratively the indicator shows nearly zero cents while of course the continuous indicator in the app keeps moving. The jittery spreading of the partials can be seen in the continuous indicator of an app, but most apps don't show us the details that I propose in the video. Jitter and spreading is 'real physics' going in in the piano sound, and of course the ear and brain hear it too, but can't measure it with the kind of precision that a machine can. 

      Steve N.



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    Steven Norsworthy
    CEO/President
    RF2BITS, Inc.
    Cardiff CA
    619-964-0101
    steven@rf2bits.com
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  • 2.  RE: Answer to Tim on Latency

    Registered Piano Technician
    Posted 07-03-2024 18:00

    Thank you.

    Also, to whom it may concern, I'm a little confused why the other posts were taken down. I'm neither a proponent or antagonist when it comes to PianoSens. This is obviously new technology and time will tell if there is demand for this kind of technology. One thing I've learned about this industry is it's not a "one size fits all." I'm sure some people will love the clarity of the unisons, others will find it sterile and uninteresting. I find the conversation fascinating and relevant.



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    Tim Foster RPT
    New Oxford PA
    (470) 231-6074
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  • 3.  RE: Answer to Tim on Latency

    Registered Piano Technician
    Posted 07-03-2024 18:52

    Tim,

    Yes, just like ETDs themselves, some like 'em, some don't. I agree. I also am puzzled by why these posts/  threads are disappearing. 

    Peter Grey Piano Doctor 



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    Peter Grey
    Stratham NH
    (603) 686-2395
    pianodoctor57@gmail.com
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  • 4.  RE: Answer to Tim on Latency

    Posted 07-03-2024 20:43
    Yes likewise 

    I'm profoundly grateful to Steven for raising issues and drawing attention to areas where being critical improves one's performance.

    Today  the pianistic diet was a Steinway B, a Bluthner baby and a Petrof baby and throughout the day I was tuning with all Stephen's issues in mind, listening carefully and watching the machine like a hawk.

    Measurements on Steven's three C5 samples show his proposition that the 2nd partial changes pitch from strike to sustain is wrong. A phase change occurs, not a frequency shift. 

    I compiled his three samples for comparison of the three samples measured by three different ETDs
    https://youtu.be/3mMtkjp07-k and anyone can make of them as they will

    It appears there is a pitch shift of the fundamental between strike and sustain of his 3 metre piano but not the 2nd partial at least

    On 
    https://youtu.be/Z_e94lRIrfo I deliberated whether strike or sustain was relevant and found it to be a red herring 

    I'm wondering if I'm using a hammer technique that's different to others. Starting on the Steinway B today I found there was a pitch shift between strike and sustain before I started.

    However I'm using a dynamic hammer technique that doesn't relate to the delay of an app to show a pitch shift. My ETD is an oscilloscope equivalent showing amplitude, frequency deviation and phase simultaneously in real time. No delay. My reactions therefore are immediate and speedy.

    A friend swears that he can correct a deviating duplex harmonic by "bending the bridge" with a deft flick of the pitch and I'm wondering if I'm experiencing a different phenomenon which causes strike and sustain pitch differences to be tuned out.

    On the Steinway, the Bluthner and the Petrof today I found that after tuning each string there was _no_ pitch change between strike and sustain but there was the expected phase shift upon change fro vertical to horizontal motion of the string vibration.

    Accordingly I wonder if I'm doing something different and whether therefore it is indeed possible to harmonise the two vibration modes to made strike/sustain a non issue. In other words it does seem possible to tune out the difference.

    In over forty years of tuning it's possible that I might have picked up a habit that works. For the first year or so I dialled up the desired frequency on an oscillator coupled to a frequency counter. This fed the timebase of an oscilloscope. A mic signal was then fed to the 'scope so I've been familiar with the piano waveforms and the dynamic changes, adapting the lever movement on the fly in real time. For the next decade I generated the frequencies by Sinclair Spectrum computer and for a decade flirted with tunelab. Changing to the CTS5 ETD brought me back to my oscilloscope days. The dots of the CTS5 indicate wave shape and amplitude rather than the digital block of software based ETD programs or apps. A swift disappearance and reappearance indicates a phase cancellation or polarity change as does a one unit shift of the wave signal.

    On a concert hall and conservatoire job sadly I haven't had the luxury of time to record video but the Yamaha GC1 video does document the considerations I attend to whilst deciding about each string.

    Best wishes 

    David P  


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    David Pinnegar, B.Sc., A.R.C.S.
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    +44 1342 850594





  • 5.  RE: Answer to Tim on Latency

    Registered Piano Technician
    Posted 07-03-2024 21:46

    All it takes for a post to disappear is for any one member of the group to flag it. Moderators review the flagged posts and the reasonable ones reappear after a bit. At least that's how I understand it's supposed to work. 



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    Floyd Gadd RPT
    Regina SK
    (306) 502-9103
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  • 6.  RE: Answer to Tim on Latency

    Registered Piano Technician
    Posted 07-03-2024 22:12

    Just thinking out loud..  Why not move the thread to some kind of "private" forum where these discussions could continue.  I spend time writing comments, hoping someone will find some interest, only to have them disappear.  If there are comments, there is interest.  There is this hyper-sensitivity to any comment mentioning a product, or anyone selling anything that might have to do with the subject being discussed.  Even if what is being discussed is actually a technology and not a product.  We're trying to push the envelope of tuning electronically, which is advancing the art of our craft.  There may be disagreement over what is being presented, and that's a good thing.  We welcome this discussion.  But to remove (hide, censor, etc.) what is an interesting and enlightening discussion is counter to what our Guild is all about.  Don't we want to improve our craft?  If someone comes up with a better way, I would think it would be welcome, at least to examine it on its merit.  That's the spirit of our organization.  I would appreciate a change in this scenario such that the discussions could continue and comments preserved, perhaps in another place, private or not.



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    Paul McCloud, RPT
    Accutone Piano Service
    www.AccutonePianoService.com
    pavadasa@gmail.com
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