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Expressing relative blade speed

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    Posted: 06/29/2017 at 5:07pm
There is a simple way for us to compare relative blade speed of different forum members' blades. It is based on the correlation between frequency and blade speed.

  1. Download the Advanced Spectrum Analyzer PRO app in Android (by Vuche Labs, it is free)
  2. Open app
  3. Click on the 3 horizontal lines on the top right
  4. Select "Enable Peak Hold"
  5. Hit play
  6. Bounce the ball on the bare blade a few times
  7. Hit pause on the app. Then see frequency with peak amplitude
So far, I see a direct correlation between blade speed and frequency. 

Examples:
Garaydia ALC: 1744 Hz
Tibhar Drinkhall Powerspin Carbon: 1571 Hz
Viscaria: 1507 Hz
Innerforce ALC.S: 1270 Hz (a notch slower)

The advantage of this method (over the plain old 'hit the blade face on the forehead' method) is that one forum member can compare blade speed with the others in a more definitive way. So, for example, if I'm interested in knowing whether the Apolonia ZLC (owned by a German member) is faster than my IF-Layer ZLC, I just compare my reading vs his.

Any obvious contradictions?

I shall try use this in blade reviews from now on. I'm interested in seeing other forum members' findings on this.

Earlier I used to use a slightly lengthier process via the PC, but a post on TTD directed me to a family of apps that one could use for this.


Edited by slevin - 06/29/2017 at 5:09pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote h0n1g Quote  Post ReplyReply Direct Link To This Post Posted: 06/29/2017 at 5:34pm
Great idea. I will add a couple of measurements tonight:

- Timo Boll ALC
- Apolonia ZLC
- Mizuno Fortius LT Light
- Xiom Vega Pro
- Xiom Vega Tour
- Nexy Zealot
- Nexy Lissom
- Nexy KJH
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Post Options Post Options   Thanks (0) Thanks(0)   Quote shinshiro Quote  Post ReplyReply Direct Link To This Post Posted: 06/29/2017 at 6:47pm
How height do you throw/bounce the boll? (I don't know if it makes a difference, haven't downloaded tha app yet)
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Post Options Post Options   Thanks (0) Thanks(0)   Quote BigFatLoop Quote  Post ReplyReply Direct Link To This Post Posted: 06/29/2017 at 6:47pm
Would this frequency measurement take into account all the other blade parameters that might influence blade speed (types of wood, # wood layers, types of carbon, # carbon layers, blade thickness, epoxy used, layer stack-up, layer spacing, etc, etc)?  Or would the measurement mostly depend on the hardness and thickness of the outer layer?

Originally posted by slevin slevin wrote:

  1. Bounce the ball on the bare blade a few times
  2. Hit pause on the app. Then see frequency with peak amplitude
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Kolev Quote  Post ReplyReply Direct Link To This Post Posted: 06/29/2017 at 7:23pm
Measuring the frequency may be helpful only if we are having blades from the same brand and model, E.g. BTY TBoll ALC.
The higher the frequency, the more the density of the wood
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Post Options Post Options   Thanks (0) Thanks(0)   Quote icontek Quote  Post ReplyReply Direct Link To This Post Posted: 06/29/2017 at 9:04pm
does the frequency vary much towards the tip, away from the sweetspot?

if so, how much?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote yogi_bear Quote  Post ReplyReply Direct Link To This Post Posted: 06/29/2017 at 9:29pm
nice

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Post Options Post Options   Thanks (0) Thanks(0)   Quote zeio Quote  Post ReplyReply Direct Link To This Post Posted: 06/29/2017 at 9:29pm
Originally posted by Kolev Kolev wrote:

Measuring the frequency may be helpful only if we are having blades from the same brand and model, E.g. BTY TBoll ALC.
The higher the frequency, the more the density of the wood

Measuring the frequency has been proven to work across blades of different compositions. There is a loose correlation between frequency and coefficient of restitution, the latter of which is the real measurement of blade speed. By comparing the frequencies, one can get a good idea of the speed of different blades.

The first few modes of vibration is of the most interest. The first mode of vibration, in particular, is low enough to feel through the palm. That said, the built-in mic on most smartphones is not good enough to detect low frequencies.
Viscaria FL - 91g
+ Neo H3 2.15 Blk - 44.5g(55.3g uncut bare)
+ Hexer HD 2.1 Red - 49.3g(68.5g 〃 〃)
= 184.8g
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Post Options Post Options   Thanks (0) Thanks(0)   Quote yogi_bear Quote  Post ReplyReply Direct Link To This Post Posted: 06/29/2017 at 9:40pm
i think we just need to have a uniform height of bounce like 6 inches? 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote iamj8 Quote  Post ReplyReply Direct Link To This Post Posted: 06/29/2017 at 10:13pm
Very nice. Once a good amount of data is assembled, the main post should be updated and post stickies. I'm sure it'll help a lot of EJs and players out there.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Baal Quote  Post ReplyReply Direct Link To This Post Posted: 06/29/2017 at 10:13pm
Height of the ball shouldn't matter.  The blade will resonate at its preferred frequencies.  It will just be louder if you drop from greater height.  Like plucking a string on a guitar, you can pluck it harder and mostly it will just be louder but the pitch and timbre is the same.

I think it is a really good idea.


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Post Options Post Options   Thanks (0) Thanks(0)   Quote zeio Quote  Post ReplyReply Direct Link To This Post Posted: 06/29/2017 at 10:37pm
Yes, amplitude will change as the drop height and the tightness of grip goes up and down, but the overall waveform will stay the same as the blade will vibrate at its natural frequencies. The location of impact will have a larger influence as that will have an effect on the modes excited. If the ball hits the node of a certain mode, that mode will not be excited.
Viscaria FL - 91g
+ Neo H3 2.15 Blk - 44.5g(55.3g uncut bare)
+ Hexer HD 2.1 Red - 49.3g(68.5g 〃 〃)
= 184.8g
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Post Options Post Options   Thanks (0) Thanks(0)   Quote JacekGM Quote  Post ReplyReply Direct Link To This Post Posted: 06/29/2017 at 10:37pm
Let us just remember to use the same ball for these comparisons... it takes two to tango.
(1) Juic SBA (Fl, 85 g) with Bluefire JP3 (red max) on FH and 0.6 mm DR N Desperado on BH; (2) Yinhe T7 (Fl, 87 g) with Bluefire M3 (red 2.0) on FH and 0.6 mm 755 on BH.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote h0n1g Quote  Post ReplyReply Direct Link To This Post Posted: 06/29/2017 at 10:56pm
Yes, ball will make an impact on frequency
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Post Options Post Options   Thanks (0) Thanks(0)   Quote h0n1g Quote  Post ReplyReply Direct Link To This Post Posted: 06/29/2017 at 11:20pm
Nittaku P40+ Ball, dropped from approximately 6 inches, three times in a row.

Mizuno Fortius LT Light :  1378 hz
Xiom Vega Pro : 1399 hz
Nexy KJH : 1291 hz
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Post Options Post Options   Thanks (0) Thanks(0)   Quote h0n1g Quote  Post ReplyReply Direct Link To This Post Posted: 06/29/2017 at 11:34pm
Here's a google submission form if you want to contribute: https://goo.gl/forms/HGki3A0DqfYSXT2A3

Here's the resulting table: Blade Speed Comparison

I will get it sorted in a bit


Edited by h0n1g - 06/29/2017 at 11:35pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote slevin Quote  Post ReplyReply Direct Link To This Post Posted: 06/29/2017 at 11:44pm
Originally posted by h0n1g h0n1g wrote:

Here's a google submission form if you want to contribute: https://goo.gl/forms/HGki3A0DqfYSXT2A3

Here's the resulting table: Blade Speed Comparison

I will get it sorted in a bit

Great idea! Nice to have a database / table. I shall try upload a few values tomorrow.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote h0n1g Quote  Post ReplyReply Direct Link To This Post Posted: 06/29/2017 at 11:51pm
First slightly questionable result: Xiom Vega Tour: 1299 vs. Xiom Vega Pro : 1399
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Post Options Post Options   Thanks (0) Thanks(0)   Quote qpskfec Quote  Post ReplyReply Direct Link To This Post Posted: 06/29/2017 at 11:58pm
I would like to see results from testing both sides of a combo blade.

A combo blade being one with an asymmetric design - different composition on each side, typically made for people to use inverted rubber on one side and LP on the other.

If one side is much softer wood than the other, are the frequencies the same?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote zeio Quote  Post ReplyReply Direct Link To This Post Posted: 06/30/2017 at 12:06am
Originally posted by h0n1g h0n1g wrote:

First slightly questionable result: Xiom Vega Tour: 1299 vs. Xiom Vega Pro : 1399

Sounds about right. Xiom official site states that the Pro is faster than Tour.

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Viscaria FL - 91g
+ Neo H3 2.15 Blk - 44.5g(55.3g uncut bare)
+ Hexer HD 2.1 Red - 49.3g(68.5g 〃 〃)
= 184.8g
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Post Options Post Options   Thanks (0) Thanks(0)   Quote zeio Quote  Post ReplyReply Direct Link To This Post Posted: 06/30/2017 at 12:10am
Originally posted by qpskfec qpskfec wrote:

I would like to see results from testing both sides of a combo blade.

A combo blade being one with an asymmetric design - different composition on each side, typically made for people to use inverted rubber on one side and LP on the other.

If one side is much softer wood than the other, are the frequencies the same?

Frequencies should be the same, but the amplitude could be different on either side.
Viscaria FL - 91g
+ Neo H3 2.15 Blk - 44.5g(55.3g uncut bare)
+ Hexer HD 2.1 Red - 49.3g(68.5g 〃 〃)
= 184.8g
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Post Options Post Options   Thanks (0) Thanks(0)   Quote haggisv Quote  Post ReplyReply Direct Link To This Post Posted: 06/30/2017 at 12:24am
Interesting idea... I can't see it working for all blades though. For example balsa blades can be very slow on low impact, yet very fast at higher impact. 
It might work for the more standard blades though.
Where is the iphone app?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote SmileTT Quote  Post ReplyReply Direct Link To This Post Posted: 06/30/2017 at 12:35am
This is amazing, I look forward to see more numbers!!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote qpskfec Quote  Post ReplyReply Direct Link To This Post Posted: 06/30/2017 at 12:40am
Originally posted by zeio zeio wrote:

Originally posted by qpskfec qpskfec wrote:

I would like to see results from testing both sides of a combo blade.

A combo blade being one with an asymmetric design - different composition on each side, typically made for people to use inverted rubber on one side and LP on the other.

If one side is much softer wood than the other, are the frequencies the same?

Frequencies should be the same, but the amplitude could be different on either side.


A combo blade is made so that the ball reacts differently depending on which side you use. The frequency is the same for both sides but the ball reacts differently for both sides. This tells me that knowing the frequency doesn't tell me which side is faster and may or may not be a very interesting fact to know.

Coefficient of restitution is much more interesting than frequency. That is why golf club designers measure COR to get the COR up to the legal limit. My guess in tt blades is that COR will vary depending on swing speed due to multiple layers of different materials.

Golf club designers measure frequency and tune the frequency. They do not try to maximize frequency for performance, it is done to make the golf club more pleasing to the ear.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote zeio Quote  Post ReplyReply Direct Link To This Post Posted: 06/30/2017 at 1:05am
Yes, that's exactly the reason I wrote "a loose correlation between frequency and coefficient of restitution" earlier.

Not just blades, but also pretty much everything will produce different CORs for different impact velocities.



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Y-axis, velocities after impact
X-axis, velocities before impact - 7.5 m/s, 15 m/s, 22.5 m/s

Edited by zeio - 06/30/2017 at 1:09am
Viscaria FL - 91g
+ Neo H3 2.15 Blk - 44.5g(55.3g uncut bare)
+ Hexer HD 2.1 Red - 49.3g(68.5g 〃 〃)
= 184.8g
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Post Options Post Options   Thanks (0) Thanks(0)   Quote h0n1g Quote  Post ReplyReply Direct Link To This Post Posted: 06/30/2017 at 1:35am
Originally posted by haggisv haggisv wrote:

Interesting idea... I can't see it working for all blades though. For example balsa blades can be very slow on low impact, yet very fast at higher impact. 
It might work for the more standard blades though.
Where is the iphone app?

https://itunes.apple.com/us/app/spectrum-analyzer-real-time-sound-frequency-analyzer/id490078884?mt=8

that should do the same
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Post Options Post Options   Thanks (0) Thanks(0)   Quote vvk1 Quote  Post ReplyReply Direct Link To This Post Posted: 06/30/2017 at 3:25am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote slevin Quote  Post ReplyReply Direct Link To This Post Posted: 06/30/2017 at 1:38pm
I suggest putting down your blade weight (if you know it). A 80g Viscaria shall show different readings than a 92g Viscaria.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Hozuki Quote  Post ReplyReply Direct Link To This Post Posted: 06/30/2017 at 2:20pm
Hm, this will be inconsistent since blade have frequency peaks of similar amplitude at various frequencies, not just one. Some ppl will surely confuse the pitch by an octave (which is simply half or double the freq).
I would find it more helpful if the actual scale a blade rings in was to be provided. However, that's neither a push-one-button method nor a task manageable by people without some knowledge about music theory.

For example, my Stiga OC (85g) has a scale of F#-Dur (detuned) and the first pronounced note is A#. If you only measure a single frequency, then you get either A#, C#, or F#. If I had to decide on one, I would say it sounds most like its prime - F#. That's 1400 Hz. Now you can add it to the list and get on with your life :P
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Post Options Post Options   Thanks (0) Thanks(0)   Quote arg0 Quote  Post ReplyReply Direct Link To This Post Posted: 06/30/2017 at 5:53pm
For a related discussion, see this thread.
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