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Experiment on Pleyel Chromatic harp: startling conclusions for piano tuning, improvement of tone and HIP

  • 1.  Experiment on Pleyel Chromatic harp: startling conclusions for piano tuning, improvement of tone and HIP

    Posted 18 days ago
    It's with great delight that finally I've been able to finish restringing the Pleyel Chromatic harp, tuning it in different ways for experiment and conducting measurements.

    Whilst I know what I've heard whilst tuning pianos, it's difficult to describe in terms of that expression that writing about music is like dancing about architecture.

    Because of the acoustic simplicity of the Pleyel chromatic harp
    The musical scale, resonance and the Pleyel Chromatic Harp
    YouTube remove preview
    The musical scale, resonance and the Pleyel Chromatic Harp
    An introduction to looking at the Pleyel Chromatic Harp and experiments in resonance. You can hear the same piece played on a Chromatic harp https://www.yout...
    View this on YouTube >

    compared to the piano with only one string to each note instead of three, it's been easier to tune quickly for experiment as well as reducing the variables so as to narrow down parameters specifically to the consequences of tuning schemes.

    I tuned it
    1. to exact equal temperament using an ETD
    2. to the bells or tone bars installed in the head of all the the 1890s instruments by Pleyel for tuning
    3. to unequal temperament using my "high definition" technique or twist to the temperament which I've found has an effect on resonance.

    The results are startling, visually demonstrable with acoustic analysis with software from Tolvan Data

    Tolvan remove preview
    Tolvan Data
    Tolvan Data was my company specialized in computer software for measurement and simulation of acoustic systems. Even though the company is resting, the web page is still available for free download of the softwares that I wrote and still write. Svante Granqvist On the menu to the left you will find the softwares for download.
    View this on Tolvan >

    (very many thanks indeed to this software provider), sheds revelatory light on Debussy and Ravel who wrote for the instrument and the sort of tuning they would be familiar with, and demonstrates how the Pleyel tuning and moreso the sort of unequal temperament and its implementation that I've been advocating which I call "High Definition", improves the sound of the chromatic harp and the sound of the piano also.

    It also demonstrates visibly why tuning was key to Chopin and Beethoven's use of the piano sustain pedal.

    If the PTG would like me to write this up in the Journal I'll be happy to do so.

    The consequences relate not only to HIP and how the whole piano repertoire should be performed and re-recorded, but how tuning can improve the sound of the instrument.

    Happy Easter!

    Best wishes

    David P



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    David Pinnegar BSc ARCS
    Hammerwood Park, East Grinstead, Sussex, UK
    +44 1342 850594
    "High Definition" Tuning
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  • 2.  RE: Experiment on Pleyel Chromatic harp: startling conclusions for piano tuning, improvement of tone and HIP

    Posted 12 days ago
    I've finally managed to test the temperament of the tuning bars on the harp.

    In cents:
    C -2.09
    C# -0.43
    D 0.37
    D# 2.16
    E 0.90
    F 0.32
    F# -1.51
    G 2.36
    G# 1.29
    A 0.00
    Bb 0.27
    B 1.64

    Best wishes

    David P

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





  • 3.  RE: Experiment on Pleyel Chromatic harp: startling conclusions for piano tuning, improvement of tone and HIP

    Posted 12 days ago
    I plugged the figures into my "PianoMeter" app and it appears to be fairly mild. The interval of C w/G seems to have more beats than I'd like for ET. It is possible the bars have changed physically since they were made. So the A was 440hz? That's interesting.

    ( I may give this a try on my 1872 straight strung Bechstein perhaps I'll adjust  that interval of a 5th in the key of C seems to beat too fast, once I've gone over it a few times. That's how I usually do it anyhow.)

    Thanks for posting these figures.

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    Richard Adkins
    Piano Technician and
    Curator of Instruments
    Coe College
    Cedar Rapids, IA
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  • 4.  RE: Experiment on Pleyel Chromatic harp: startling conclusions for piano tuning, improvement of tone and HIP

    Posted 12 days ago
    It was intended to be pitched at old "French International Pitch" at 15 degrees C at 435 but is actually at 436

    The bars seem unlikely to have been able to change although my house is currently at probably around 11 degrees rather than 15. But there is an unevenness in the variations. The fact is that this appears to be evidence that Equal Temperament even if intended couldn't be tuned accurately and or may have been intentionally tweaked. 

    In the frequency spectra that I've been doing, Equal Temperament causes visible confusion whilst the Pleyel tweak separates the notes better in sustain - so if trying this temperament, I'd try it exactly as given.

    Measuring with the gStrings app on an Android tablet
    Frequencies of bars:
    A 871.8
    A# 923.3/4.3
    B 979.4
    C 1034/5
    C# 1097/8
    D 1162/3/4
    D# 1233/4/5
    E 1305/7
    F 1383
    F# 1462/3/4
    G 1555
    G# 1646

    Measuring offsets with CTS5 tuner some slightly different results but it depends what each device is listening for I guess - 
    A 0 
    A# 1 to 1.5
    B .5
    C -1
    C# -1.5
    D -1
    D# 0
    E -1.5
    F -1.5
    F# -2
    G .5
    G# -0.5

    How one reconciles these I'm not sure. However, attached are frequency analyses of the instrument with all strings at once following a glissando and the sustain frequencies of the tuning given by the Pleyel tuning bars (Bell tuning) appear to be more defined.   With the unequal temperament I apply to pianos, the definition is even better.

    Because the minor tweaking seems to give more definition to the sound I reckon it's worth trying on pianos without significantly losing effective equal temperament characteristics

    If anyone's interested I've been talking with George Davis (Bill) about a possible presentation to the South East Region.

    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: Experiment on Pleyel Chromatic harp: startling conclusions for piano tuning, improvement of tone and HIP

    Member
    Posted 9 days ago
    Hello David,

    Wonderful video and very insightful observations! My own work maintaining and restoring historic instruments for local collections has allowed some similar in-the-moment research as I restore, but this is very detailed- nice work!

    Be well,

    Ian

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    Ian Graham
    Piano Technician
    www.igraham.ca
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  • 6.  RE: Experiment on Pleyel Chromatic harp: startling conclusions for piano tuning, improvement of tone and HIP

    Posted 9 days ago
    Thanks and it's really great to know that the work is being appreciated.

    I will be writing up results either for an academic paper or possibly if of interest with encouragement, for the Journal and or be willing to do a South East seminar if of sufficient  interest.

    Some preliminary results are attached - a larger Bechstein, a Steinway M and the Pleyel harp all in my "High Definition" twist of unequal temperament. It appears clear that the comparison of pianos and the chromatic harp is valid. Attached also is the same graph presenting the harp in standard Equal Temperament.

    The Equal Temperament chart shows a mess of frequencies between the notes, and with other settings maintained, the graph presentation sensitivity had to be raised by around 6dB in order to show the same sort of extent of loudness shown by the red lines. This observed increase of sound when we bring the instrument into unequal temperament accords with what we have observed with pianos.

    Some time back on a thread about temperament research when I first joined the PTG forum I presented spreadsheets which calculated the proportion of notes of the scale that matched the harmonics of strings below. From memory, Equal Temperament gave around a 28% correlation whilst the unequal temperament approached around 35%. The charts from the experimental measurement support the mathematical expectations.

    In another series of charts which I coin the word "chromosones" I'm looking at the energy given to particular frequencies of accordance.

    Having now demonstrated correspondence of behaviour between chromatic harp and piano, and from the harp seen potentially what we might expect to see from measuring a piano, if anyone would be interested in doing two recordings from which we can extract the charts for the behaviour of a well tuned equal temperament or P12 tuned piano (and some have mentioned Reynolds), the comparisons might well be very interesting indeed.

    As an aside, on the Pleyel tuned in the High Definition temperament, often one can pluck a string and damp it immediately, and the rest of the instrument sings and continues the sound as though the initial string was still vibrating. The damping makes no difference.

    This is about how we can get the piano to sound better, to work better as a musical instrument, to convey music, to convey emotion better and to get people more excited about classical music and even how the piano can generate more enthusiasm, particularly than electronic competition. It might even be a reason for the whole of the classical repertoire to be re-recorded and give a whole new boost to the recording industry and live performance.

    Does anyone know Daniel Barenboim? I'd love to be tuning his straight strung piano. From my experience of the straight strung historic instruments I believe I could make it come alive as even he never expected under his fingers.

    Best wishes

    David P

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