ChanterRacquet
Professional
Edit: Newer data is posted in the next reply.
Here recently I've been toying with measuring string vibration frequency as a metric of tension loss to see if I could restring just the crosses in my wife's fullbed of NXT when she frays the crosses to nothing in 3 hours, seemingly leaving the mains intact. Then, in a recent thread I was inspired to see if any of my audio equipment from recording my music could also be used to analyze vibration frequencies of racquets.
After some tinkering I have some interesting results. Using a piezo microphone held into place on the highest flat spot on the handle before it splits at the yoke, I monitored the resulting vibration spectrum using the iPhone AudioTools app which is capable of doing FFT (fast fourier transform) which shows me the amplitude across a spectrum of frequencies.
Now, what's really interesting is the difference between striking the string bed in the sweet spot (where the frame isn't supposed to result in vibrating) versus striking the string bed in what I'm going to call a shank spot (anywhere but the middle gives you the same result: low, high, sides).
Below is the spectrum when you hit a shank spot on a Blade 104 v7. You can see a global maximum at 123 Hz (within the field of view anyway) which corresponds to the frame vibration reported by TWU. There are other frequencies too. This is without a dampener.
Below is the spectrum if you hit the sweet spot on the same racquet. Notice how the frame vibration at 123 Hz dissipates leaving behind the string vibration frequency at 533 Hz. This is without a dampener.
So I'm thinking there's no point in worrying about the frame's vibration frequency, even if it is attributable to arm damage, unless you really suck at hitting the sweet spot.
What one might also consider interesting is that adding a dampener attenuated the frame vibration so as to be less than the string vibration even when striking the shank spot! The string vibration frequency also increased by 14 Hz.
The absolute magnitude between the experiments is different so I need to figure out how to ensure I'm striking the string bed with a consistent force so I can compare separate scenarios for magnitude, but I'm fairly confident in the present results.
If we assume the absolute magnitude of the plots can be compared, the dampener doesn't attenuate the racquet vibration all that much (just above 70 to just below 70), but somehow increases the amplitude of the string vibration (above 60 to above 80) which might be even weirder!
Here recently I've been toying with measuring string vibration frequency as a metric of tension loss to see if I could restring just the crosses in my wife's fullbed of NXT when she frays the crosses to nothing in 3 hours, seemingly leaving the mains intact. Then, in a recent thread I was inspired to see if any of my audio equipment from recording my music could also be used to analyze vibration frequencies of racquets.
After some tinkering I have some interesting results. Using a piezo microphone held into place on the highest flat spot on the handle before it splits at the yoke, I monitored the resulting vibration spectrum using the iPhone AudioTools app which is capable of doing FFT (fast fourier transform) which shows me the amplitude across a spectrum of frequencies.
Now, what's really interesting is the difference between striking the string bed in the sweet spot (where the frame isn't supposed to result in vibrating) versus striking the string bed in what I'm going to call a shank spot (anywhere but the middle gives you the same result: low, high, sides).
Below is the spectrum when you hit a shank spot on a Blade 104 v7. You can see a global maximum at 123 Hz (within the field of view anyway) which corresponds to the frame vibration reported by TWU. There are other frequencies too. This is without a dampener.
Below is the spectrum if you hit the sweet spot on the same racquet. Notice how the frame vibration at 123 Hz dissipates leaving behind the string vibration frequency at 533 Hz. This is without a dampener.
So I'm thinking there's no point in worrying about the frame's vibration frequency, even if it is attributable to arm damage, unless you really suck at hitting the sweet spot.
What one might also consider interesting is that adding a dampener attenuated the frame vibration so as to be less than the string vibration even when striking the shank spot! The string vibration frequency also increased by 14 Hz.
The absolute magnitude between the experiments is different so I need to figure out how to ensure I'm striking the string bed with a consistent force so I can compare separate scenarios for magnitude, but I'm fairly confident in the present results.
If we assume the absolute magnitude of the plots can be compared, the dampener doesn't attenuate the racquet vibration all that much (just above 70 to just below 70), but somehow increases the amplitude of the string vibration (above 60 to above 80) which might be even weirder!
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