Nylon Guqin String Trial #13


This trial is currently the best iteration I have made so far for a rope style twisted nylon guqin string, for string #7. Given calculations to estimate the diameter, the next increase of thread number will result in a string that may be slightly too large for string 7 for the given tuning, though more tests will need to be run to confirm this. The primary twist number was increased from trial #11, but had to be decreased from 2550 turns from trial #12, which failed during the making process. The secondary twist weight was also increased to 5lbs, and with this number of twists, strands, weight, type of string, and original starting length, this trial is optimized right before the breaking point of the string. Throughout my string making trials so far, I have found that this style of twisted strings, whether made from nylon or polyester so far, are generally better if they are made by twisting with the proper weight right before the breaking point of the string. This however can only be found through trial and error, pushing the limit of the string until it breaks, then backing off on the twist number slightly. Since this style of string currently does not use glue to hold it together, using the maximum twist number with highest possible tension weight will result in much tighter twists and a naturally stiffer string.

Included in this page are all of the major string parameters that I have obtained so far for this string, as well as all relevant data I have collected and analyzed for this string, including harmonic content data, spectrograms, and autocorrelation graphs. You can enlarge the images by clicking on the thumbnails.


STRING TRIAL #13 PARAMETERS

Material: Nylon

Thread: Middleburg Thread #15 Nylon Beige

Thread Diameter (in.): 0.0048″

Theoretical Calculated Twisted Substrand Diameter (in.): 0.01590″

Theoretical Calculated Twisted Total Diameter (in.): 0.0343″

Thread Strength: 2lbs

# of Substrands: 3

# of Threads per Substrand: 8

Total Thread Count: 24

# of Primary Twists: 2437.5

Twist Angle (degrees): 41.2

Substrand Twist Direction: Clockwise

String Twist Direction: Clockwise

Primary Twisting Tension: 3lbs

Secondary Twisting Tension: 5lbs

Starting Length (in.): 120″

Ending Length (in.): 103″


STRING TRIAL #13 DATA

1. Linear Spectrum Harmonic Content Graphs

 

2. Autocorrelation

 

3. Spectrograms (Window 4096)

 

4. Spectrograms (Window 2048)

 

5. Spectrograms (Window 512)


DATA DESCRIPTIONS

  1. Linear Spectrum Harmonic Content Graphs – Shows the harmonic content of each string, graphed along the linear spectrum in terms of frequency to intensity. A very accurate way to easily visualize the harmonics and overtones of each string.
  2. Autocorrelation – Shows the periodic nature or trends from a given set of data. Autocorrelation can provide a unique look at data, and can reveal repeating patterns from seemingly random datapoints. For this application, it is derived from the original signal and more clearly shows the decaying oscillatory nature of the plucked string.
  3. Spectrograms (Window 4096) – Shows the spectrogram of each string, with a window setting of 4096. This setting allows one to clearly view all of the harmonics by showing the frequency, intensity, and duration of each harmonic. This graph can be most easily cross-correlated to the linear spectrum harmonic content graphs to compare durations and intensities of harmonics in a string.
  4. Spectrograms (Window 2048) –  Shows the spectrogram of each string, with a window setting of 2048. For this application, I have found that this setting is ideal in viewing the oscillatory instabilities of the guqin string more clearly, which cannot be seen as well in higher window settings. These are seen as wavering lines, which are most noticeably present in the mid-upper harmonics.
  5. Spectrograms (Window 512) – Shows the spectrogram of each string, with a window setting of 512. For this application, I have found that this setting, while having the lowest frequency band resolution of the three settings, allows one to zoom out on the entirety of the harmonic spectrum, and see how the overall power level and intensity shifts from one string to another, and where the harmonic content is overall most present for a given string.