Expressing relative blade speed
Printed From: Alex Table Tennis - MyTableTennis.NET
Category: Equipment
Forum Name: Equipment
Forum Description: Share your experience and discussions about table tennis equipments.
Moderator: haggisv
Assistant Moderators: position available
URL: http://mytabletennis.net/forum/forum_posts.asp?TID=79533
Printed Date: 04/26/2024 at 12:55am
Software Version: Web Wiz Forums 12.01 - http://www.webwizforums.com
Topic: Expressing relative blade speed
Posted By: slevin
Subject: Expressing relative blade speed
Date 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.
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.
------------- Trade feedback: http://mytabletennis.net/forum/forum_posts.asp?TID=50787" rel="nofollow - http://mytabletennis.net/forum/forum_posts.asp?TID=50787 |
Replies:
Posted By: h0n1g
Date 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 ------------- --- http://mytabletennis.net/forum/forum_posts.asp?TID=71705&title=feeback-h0n1g" rel="nofollow - My Feedback Thread |
Posted By: shinshiro
Date 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) |
Posted By: BigFatLoop
Date 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?
|
slevin wrote:Posted By: Kolev
Date 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 ------------- Hallmark Carbon Extreme (x3) FH: D05/G1/RX BH: Z2/D64/Ω7Pro |
Posted By: icontek
Date Posted: 06/29/2017 at 9:04pm
|
does the frequency vary much towards the tip, away from the sweetspot? if so, how much? ------------- http://bit.ly/vLMhuB" rel="nofollow - - RC1042 . OSP Virtuoso AC: PK50 + R42 |
Posted By: yogi_bear
Date Posted: 06/29/2017 at 9:29pm
|
nice ------------- Independent online TT Product reviewer of XIOM, STIGA, JOOLA, SANWEI, GEWO, AIR, ITC, APEX, YASAKA and ABROS ITTF Level 1 Coaching Course Conductor, ITTF Level 1 Coach |
Posted By: zeio
Date Posted: 06/29/2017 at 9:29pm
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 |
Posted By: yogi_bear
Date Posted: 06/29/2017 at 9:40pm
|
i think we just need to have a uniform height of bounce like 6 inches? ------------- Independent online TT Product reviewer of XIOM, STIGA, JOOLA, SANWEI, GEWO, AIR, ITC, APEX, YASAKA and ABROS ITTF Level 1 Coaching Course Conductor, ITTF Level 1 Coach |
Posted By: iamj8
Date 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. ------------- A version of Hurricane 3 A version of Tenergy A Stiga blade... |
Posted By: Baal
Date 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. |
Posted By: zeio
Date 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 |
Posted By: JacekGM
Date 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. |
Posted By: h0n1g
Date Posted: 06/29/2017 at 10:56pm
|
Yes, ball will make an impact on frequency ------------- --- http://mytabletennis.net/forum/forum_posts.asp?TID=71705&title=feeback-h0n1g" rel="nofollow - My Feedback Thread |
Posted By: h0n1g
Date 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 ------------- --- http://mytabletennis.net/forum/forum_posts.asp?TID=71705&title=feeback-h0n1g" rel="nofollow - My Feedback Thread |
Posted By: h0n1g
Date Posted: 06/29/2017 at 11:34pm
|
Here's a google submission form if you want to contribute: http://goo.gl/forms/HGki3A0DqfYSXT2A3" rel="nofollow - https://goo.gl/forms/HGki3A0DqfYSXT2A3 Here's the resulting table: https://docs.google.com/spreadsheets/d/1tnzuhP98Iwl3_ZYIKs770Z4GeEXB1cPaF6xXC3IMLfg/edit?usp=sharing" rel="nofollow - Blade Speed Comparison I will get it sorted in a bit
------------- --- http://mytabletennis.net/forum/forum_posts.asp?TID=71705&title=feeback-h0n1g" rel="nofollow - My Feedback Thread |
Posted By: slevin
Date Posted: 06/29/2017 at 11:44pm
Great idea! Nice to have a database / table. I shall try upload a few values tomorrow. ------------- Trade feedback: http://mytabletennis.net/forum/forum_posts.asp?TID=50787" rel="nofollow - http://mytabletennis.net/forum/forum_posts.asp?TID=50787 |
Posted By: h0n1g
Date Posted: 06/29/2017 at 11:51pm
|
First slightly questionable result: Xiom Vega Tour: 1299 vs. Xiom Vega Pro : 1399 ------------- --- http://mytabletennis.net/forum/forum_posts.asp?TID=71705&title=feeback-h0n1g" rel="nofollow - My Feedback Thread |
Posted By: qpskfec
Date 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? |
Posted By: zeio
Date Posted: 06/30/2017 at 12:06am
Sounds about right. Xiom official site states that the Pro is faster than Tour. Vega Tour  Vega Pro  ------------- 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 |
Posted By: zeio
Date Posted: 06/30/2017 at 12:10am
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 |
Posted By: haggisv
Date 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? ------------- Smart; VS>401, Dtecs OX http://tabletennisshop.com.au/index.php?main_page=page&id=42" rel="nofollow - Tenergy Alternatives | http://tabletennis-reviews.com" rel="nofollow - My TT Articles |
Posted By: SmileTT
Date Posted: 06/30/2017 at 12:35am
|
This is amazing, I look forward to see more numbers!! ------------- Xiom Omega IV Euro | Freitas ALC | Xiom Omega IV Euro https://tinyurl.com/yaoh8suu" rel="nofollow - Feedbacks |
Posted By: qpskfec
Date Posted: 06/30/2017 at 12:40am
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. |
Posted By: zeio
Date 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.  Bryce Speed Bryce Sriver Y-axis, velocities after impact X-axis, velocities before impact - 7.5 m/s, 15 m/s, 22.5 m/s ------------- 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 |
Posted By: h0n1g
Date Posted: 06/30/2017 at 1:35am
https://itunes.apple.com/us/app/spectrum-analyzer-real-time-sound-frequency-analyzer/id490078884?mt=8 that should do the same ------------- --- http://mytabletennis.net/forum/forum_posts.asp?TID=71705&title=feeback-h0n1g" rel="nofollow - My Feedback Thread |
Posted By: vvk1
Date Posted: 06/30/2017 at 3:25am
|
Adidas Hypertouch: 1.6 Khz Nexy Chedech: 1.4 Khz
|
Posted By: slevin
Date 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. Butterfly Marcos Freitas ALC (87g): 1464 ------------- Trade feedback: http://mytabletennis.net/forum/forum_posts.asp?TID=50787" rel="nofollow - http://mytabletennis.net/forum/forum_posts.asp?TID=50787 |
Posted By: Hozuki
Date 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 |
Posted By: arg0
Date Posted: 06/30/2017 at 5:53pm
|
For a related discussion, see http://mytabletennis.net/forum/forum_posts.asp?TID=38419" rel="nofollow - this thread . ------------- Nexy Arche & Nittaku Violin LG. Join the forum_posts.asp?TID=47778" rel="nofollow - Nexy Clan ! Also member of Violin & 1-Ply clans. |
Posted By: berndt_mann
Date Posted: 06/30/2017 at 6:09pm
|
I still retain some knowledge about music theory, though its been 52 years since I last studied music theory at the Cleveland, Ohio Institute of Music. It never occurred to me, however, or any other table tennis player I knew to try to measure the amplitude or frequency peaks of any of the blades I used while also studying classical defensive table tennis theory under six-time Ohio State Champion and two-time National Doubles Champion Danny Vegh. Now, however, my curiousity has been piqued. I'm wondering what the scale (modal, pentatonic, hexatonic, microtonal) might have been for the American birch/basswood/birch 3-play Hock No. 74 blade I played with affixed with British Leyland hard rubber for most of my training or the Cor DuBuy red oak/European birch/red oak Loop Drive blade affixed with Butterfly
D-13 sandwich sponge inverted rubber that I took along with me as well as the Hock when I enlisted in the Army. Polytonality, perhaps between the two? Twelve-tone serialism? A pity I shall never know.
------------- bmann1942 Setup: Mark Bellamy Master Craftsman blade, British Leyland hard rubber |
Posted By: arg0
Date Posted: 06/30/2017 at 6:22pm
I suspect recording and spectrum analysis equipment was less readily available, then. Studying mechanical response of the blades is interesting to some. Does it make you a better player? No. Does it give you at least one objective criterion to assess blade characteristics? Yes. ------------- Nexy Arche & Nittaku Violin LG. Join the forum_posts.asp?TID=47778" rel="nofollow - Nexy Clan ! Also member of Violin & 1-Ply clans. |
Posted By: slevin
Date Posted: 06/30/2017 at 7:25pm
|
Cool, arg0's done this before! Garaydia ZLC (85g): 1830 So far, very true to expectations. ------------- Trade feedback: http://mytabletennis.net/forum/forum_posts.asp?TID=50787" rel="nofollow - http://mytabletennis.net/forum/forum_posts.asp?TID=50787 |
Posted By: Baal
Date Posted: 06/30/2017 at 8:28pm
It's not just weight though. I have two Viscaias of the same weight that have a different tone when I knock them against my head, and it would certainly show up on this measurement. And yes, the one with a higher pitched tone is faster |
Posted By: Baal
Date Posted: 06/30/2017 at 8:31pm
Very good point. |
Posted By: Baal
Date Posted: 06/30/2017 at 8:36pm
Including the range of mechanical responsex seen for different samples of a particular type of blade. |
Posted By: zeio
Date Posted: 06/30/2017 at 8:42pm
|
Other than the speed, the mode of vibration can reveal a lot about a blade. The 1st bending mode is usually within the first few hundred Hz, lower for a clamped blade, and higher for a freely-suspended blade, with the real-world grip resembling the latter, but with higher damping. The 1st torsional mode follows closely. The 2nd bending mode comes next, and so on. The membrane mode doesn't come in until much later. The 1st bending mode contributes the most to dwell/feel as the handle vibrates the most at that frequency. That mode is also related to the sweet spot as one node(least vibration) is somewhere in the upper center of the blade head and another node where the handle meets the blade head. The 1st torsional mode gets agitated the most when the racket is hit off-centered. As the mode goes higher, the role it has in the racket-ball interaction diminishes. Looking at the data, it looks like the mic is picking up the membrane mode the most, which contributes the most to the sound of the blade. ------------- 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 |
Posted By: BigFatLoop
Date Posted: 06/30/2017 at 8:55pm
|
Sure, yeah!! ... I agree with everything you just said so please put me down as the co-author.  Thanks!
|
Posted By: berndt_mann
Date Posted: 06/30/2017 at 9:24pm
|
Holy crap! Blade amplitude theory is a lot more complicated than Werner Von Braun rocket science. What ever happened to a good old simple game of ping pong? Damn. Do y'all take along an IBM Watson to make sure that the physics, acoustics, chemistry, and even meteorology are just right for your respective styles before contemplating entering the U-1800 event at the Whistlestop, Wyoming come one come all two-star invitational (free chocolate chip cookies, homemade lemonade, and you get to ride a Mustang [a real one, not the car])? (Lots of involuntary head shaking from your no longer fearless author) ------------- bmann1942 Setup: Mark Bellamy Master Craftsman blade, British Leyland hard rubber |
Posted By: Baal
Date Posted: 06/30/2017 at 10:38pm
|
At some point I predict people will be providing this number for blades they sell here. I think this will be really useful for comparisons within a blade class-- comparisons of one all wood to another, or comparing two different ALC/ZLC blades. Zeio is right to remind us that how or if the blade is secured will potentially affect tbe result. |
Posted By: h0n1g
Date Posted: 06/30/2017 at 10:55pm
|
Agree with what Baal says, i think it is an excellent indicator. Is it the final truth? No, but I think it will provide people with a better idea of what sort of "speed" they are actually after. ------------- --- http://mytabletennis.net/forum/forum_posts.asp?TID=71705&title=feeback-h0n1g" rel="nofollow - My Feedback Thread |
Posted By: Baal
Date Posted: 06/30/2017 at 10:59pm
|
IMHO certainly better than anything we have had before. Especially given that the apps are free. Congratulations to those of you who independently came up with this. One thing that occurs to me to add. I have about nine or so Viscarias, but one is amazingly better than all the others to play with. It is the best blade I have ever played with and I am really lucky to have it (I bought it here by the way). It is not just the weight, and it is not just the pitch when I knock it against my head. I have a couple of other blades that are similar in terms of weight and pitch (although a lot of them have a higher pitch and don't feel anywhere close to as good). Somehow this blade's sound seems to be a lot more "pure" and seems to resonate longer. Next time I change the rubber I will get this app and compare it to some of its lesser brethren to see if some difference shows up in its spectrum (I expect this would show up in the higher components of the spectrum). Might be awhile though, the rubber that is on it refuses to die and is playing great right now, so I don't want to mess with anything. It may depend a lot on how good the pickups are in my phone. |
Posted By: h0n1g
Date Posted: 07/01/2017 at 12:24am
|
I've added all submissions to the sheet I posted. Also added two of my blades: Timo Boll ALC and Apolonia ZLC https://docs.google.com/spreadsheets/d/1tnzuhP98Iwl3_ZYIKs770Z4GeEXB1cPaF6xXC3IMLfg/edit?usp=sharing" rel="nofollow - Blade Speed Comparison
------------- --- http://mytabletennis.net/forum/forum_posts.asp?TID=71705&title=feeback-h0n1g" rel="nofollow - My Feedback Thread |
Posted By: h0n1g
Date Posted: 07/01/2017 at 3:09am
|
I've also added arg0's list to the sheet ------------- --- http://mytabletennis.net/forum/forum_posts.asp?TID=71705&title=feeback-h0n1g" rel="nofollow - My Feedback Thread |
Posted By: Magic_M
Date Posted: 07/01/2017 at 4:09am
|
Sorry guys, I really like the idea, but some of the results have nothing to do with my former impressions. http://https://docs.google.com/spreadsheets/d/1tnzuhP98Iwl3_ZYIKs770Z4GeEXB1cPaF6xXC3IMLfg/edit#gid=0" rel="nofollow - http://https://docs.google.com/spreadsheets/d/1tnzuhP98Iwl3_ZYIKs770Z4GeEXB1cPaF6xXC3IMLfg/edit#gid=0
Do you really think or believe, that a WSC and PPA are faster than a PPP ? Does it sound realistic, that a low weight P500 (80g) is as fast as a 91g Tenor or as a Clipper Wood? OTC is as fast as Boll ZLC and faster than Mizutani? Maze and KSL are also faster than Mizutani? For me the OTC is slower than Boll ALC and Mizutani is as fast as Boll ZLC. I don`t know the reasons (different kind of balls, different distance form ball to smartphone, different hight, different kind of bouncing, ....), but fact is, that a buyer will be extremely surprised if he relied on these results. I would like to see his eyes, if he is playing an OTC now and is looking for something slower. So he looks in this docsheet and decides to buy the "slower" Mizutani ZLC. Another one plays the Tenor and wants something lighter, but as fast and decides to buy a P500. I am sure, both will have "interesting" results in their next training-session.  Once again: the idea is really great, but the test-conditions have to be as equal as possible. Otherwise the results are not worth anything. ------------- http://mytabletennis.net/forum/forum_posts.asp?TID=51774&title=feedback-magic-m" rel="nofollow - My Feedback |
Posted By: slevin
Date Posted: 07/01/2017 at 7:24am
Re: Magic_M's concerns:
------------- Trade feedback: http://mytabletennis.net/forum/forum_posts.asp?TID=50787" rel="nofollow - http://mytabletennis.net/forum/forum_posts.asp?TID=50787 |
Posted By: Hozuki
Date Posted: 07/01/2017 at 8:59am
|
I know why the measurements are faulty. First of all, impact strenght or ball type or height does not matter. Secondly, a blade does not have a single pitch. It has multiple pitches. The ones that are most dominant are the prime, third and fifth of the underlying scale. And that's why there is confusion here, as nobody bothers to identify the prime of the scale. Instead ppl would measure either one of those three dominant tones, yielding a variation of up to half an octave, or 1.5 times the frequency. For example, arg0 measured the OC with 1100 Hz (fifth = C#), while I knew that the prime is F# from my own spectal analysis, so I posted 1400 Hz instead. And surely, somebody would happen to measure the third (A# = 932 Hz), since it is quite dominant as well. I argue that measuring the prime instead of randomly measuring the 3rd or 5th instead will yield much more reliable data. |
Posted By: arg0
Date Posted: 07/01/2017 at 10:12am
Yes, the highest peak in the audio spectrum is typically the frequency of the membrane mode. Sound amplitudes at lower frequencies are normally deadened by the hand holding the blade. ------------- Nexy Arche & Nittaku Violin LG. Join the forum_posts.asp?TID=47778" rel="nofollow - Nexy Clan ! Also member of Violin & 1-Ply clans. |
Posted By: arg0
Date Posted: 07/01/2017 at 10:17am
The frequency of the highest peak does not vary much under different test conditions. But it is not directly related to speed, not even when taking weight into account. ------------- Nexy Arche & Nittaku Violin LG. Join the forum_posts.asp?TID=47778" rel="nofollow - Nexy Clan ! Also member of Violin & 1-Ply clans. |
Posted By: arg0
Date Posted: 07/01/2017 at 10:26am
|
Some theory of blade mechanics with some great illustrative images are in this thread http://mytabletennis.net/forum/forum_posts.asp?TID=60725" rel="nofollow - http://mytabletennis.net/forum/forum_posts.asp?TID=60725 Where's John Staley, aka JRSDallas? We miss you! I wonder whether he further elaborated on/published his theory.    More recent scientific articles exploring the relationship between blade mechanics and acoustics http://www.sciencedirect.com/science/article/pii/S1877705814005840" rel="nofollow - http://www.sciencedirect.com/science/article/pii/S1877705814005840 http://www.sciencedirect.com/science/article/pii/S1877705812017316" rel="nofollow - http://www.sciencedirect.com/science/article/pii/S1877705812017316 ------------- Nexy Arche & Nittaku Violin LG. Join the forum_posts.asp?TID=47778" rel="nofollow - Nexy Clan ! Also member of Violin & 1-Ply clans. |
Posted By: Baal
Date Posted: 07/01/2017 at 11:42am
|
There is a really cool animation here, int this case of a circular membrane under tension, but still really interesting. http://www.acs.psu.edu/drussell/Demos/MembraneCircle/Circle.html" rel="nofollow - http://www.acs.psu.edu/drussell/Demos/MembraneCircle/Circle.html |
Posted By: h0n1g
Date Posted: 07/01/2017 at 12:18pm
|
I don't think the distance to the blade has a direct effect on frequency unless you are recording multiple meters away and with objects blocking the sound path. I've recorded mine about 10-15cm away from the phone. Again I think we can't expect laboratory conditions and results but I still think this gives a good indication of what kind of speed to expect. ------------- --- http://mytabletennis.net/forum/forum_posts.asp?TID=71705&title=feeback-h0n1g" rel="nofollow - My Feedback Thread |
Posted By: arg0
Date Posted: 07/01/2017 at 4:08pm
|
BTW, the frequencies below about 1000 Hz are deadened/absorbed by the player's hand only if the blade is gripped tightly. When recording the sound, I normally tend to lay the blade flat between two fingers (see picture; and no, the picture is deceiving: my index finger touches only the handle), so that the grip force is minimal and few vibrations are absorbed by my hand.  ------------- Nexy Arche & Nittaku Violin LG. Join the forum_posts.asp?TID=47778" rel="nofollow - Nexy Clan ! Also member of Violin & 1-Ply clans. |
Posted By: arg0
Date Posted: 07/01/2017 at 4:13pm
The animation is cool, but this is not how a table tennis blade vibrates. In the circular membrane animation the whole outer perimeter is fixed. In a blade, the only relatively fixed part of the blade face is where it meets the handle. ------------- Nexy Arche & Nittaku Violin LG. Join the forum_posts.asp?TID=47778" rel="nofollow - Nexy Clan ! Also member of Violin & 1-Ply clans. |
Posted By: apodra74
Date Posted: 07/01/2017 at 4:47pm
|
I tested my blades again today what I noticed that can make your measurements go all over the place is if you hold the blade lightly or really tight. Btw I tried with Donic ball p40+ and with a Nittaku Premium 40+ similar results with both balls loose grip, the blades I tested: Stiga Ulf Tickan Carrlson allround AN 82gr (30 years old) = 1184 Donic Ovtcharov Carbospeed FL 88gr = 1674 Butterfly Schlager Carbon ST 95gr = 1943 Butterfly Schlager Carbon FL 100gr = 1948 Xiom Axelo FL 87 gr. = 1981 |
Posted By: h0n1g
Date Posted: 07/01/2017 at 5:17pm
|
Added to the list. Just by looking at the numbers submitted from a number of different people, there is no doubt that this will be a decent indicator for blade speed. ------------- --- http://mytabletennis.net/forum/forum_posts.asp?TID=71705&title=feeback-h0n1g" rel="nofollow - My Feedback Thread |
Posted By: arg0
Date Posted: 07/01/2017 at 6:20pm
Loose grip is key! also see my post above. ------------- Nexy Arche & Nittaku Violin LG. Join the forum_posts.asp?TID=47778" rel="nofollow - Nexy Clan ! Also member of Violin & 1-Ply clans. |
Posted By: NextLevel
Date Posted: 07/01/2017 at 6:54pm
|
The most surprising thing I have seen so far is how far the Koto ALC blades are from blades like the Korbel or the KJH. I hope someone has put in an HL5 now. This is great stuff and I commend slevin for getting this started. Over time, it is possible that frequency, top ply hardness, overall thickness. Handle dimensions etc. Might lead to an overall blade specification that predicts ahead of time whether someone will like a blade or not. ------------- https://youtu.be/jhO4K_yFhh8?t=115" rel="nofollow - I like putting heavy topspin on the ball... Cybershape Carbon FH/BH: H3P 41D. Lumberjack TT, not for lovers of beautiful strokes. No time to train... |
Posted By: NextLevel
Date Posted: 07/01/2017 at 6:56pm
Hmmm... That looks different from what so remember and the Tour I had was faster than the Pro. But again, blades are blades. ------------- https://youtu.be/jhO4K_yFhh8?t=115" rel="nofollow - I like putting heavy topspin on the ball... Cybershape Carbon FH/BH: H3P 41D. Lumberjack TT, not for lovers of beautiful strokes. No time to train... |
Posted By: JacekGM
Date Posted: 07/01/2017 at 7:53pm
|
This is all great, for some kind of blade comparison, especially after the method of measurement is somehow standardized.  ... but guys, we play with RACKETS (blade + glue + rubber) NOT WITH BLADES  . How a racket feels to me or "plays" will depend on so many other factors than just the vibration frequency of the blade.
------------- (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. |
Posted By: JacekGM
Date Posted: 07/01/2017 at 8:40pm
This I am not convinced about... actually, I am pretty sure the pitch will be different when using one side vs the other. ------------- (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. |
Posted By: JacekGM
Date Posted: 07/01/2017 at 8:44pm
Wow, this is pretty much very related... Thanks for pointing this out. ------------- (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. |
Posted By: Baal
Date Posted: 07/01/2017 at 8:52pm
|
In terms of evaluating blades, what have we had in terms of objective
measures? Weight, and blade dimensions and thickness, and really that
is about it. We also have completely subjective measures of "speed" and
"control" with numbers that people pull out of thin air. So we don't
really know how well something like this can work unless we try it. The
blade manufacturers will never provide it, they thrive on EJs and
confusion. In fact, I suspect a more detailed analysis of what these
phone apps give would tell us a great deal, but just getting the one
number is helpful within limits -- such comparing two blades that might
be regarded as similar -- like a Donic True Carbon with one of the Btfl
ALC blades for one example. I know that there is obviously a certain quality of blades that makes them great that cannot be easily captured in a single number, but it might be surprising how few numbers we might need to home in something we would like a lot. This reminds me of mountain bikes, which were not invented by any one person, but by grass roots innovation like this. I think this is one of the best things I have seen on TT forums in a long time, and it is quite interesting that the idea is "in the air" and it turns out that several people around the world have been playing around with this (so there is already a quite large database). You guys who have been making these measurements are awesome. |
Posted By: Baal
Date Posted: 07/01/2017 at 8:54pm
No, I am quite sure the blade will vibrate as something intermediate between what you would get if the blade had been made with all of one or the other materials. I am inferring that from the two articles Arg0 cited earlier on acoustic analyses of blades. (By the way, I knew that the drum head is different from a TT blade because it is fixed around its entire perimeter, but it was still cool to look at). By the way, Hozuki raised an interesting point. Has anyone else given any thought to that? |
Posted By: book4all
Date Posted: 07/01/2017 at 11:44pm
|
I think the recording hardware may make differences. That means different cell phones may produce different benchmark frequency numbers. The result will make a lot of sense from one person's collection because using the same recording device and still make quite a bit sense even using different recording devices. So adding cell phone model information may help to explain the differences. BTW this database of frequencies can help identify fake blades. :)
|
Posted By: h0n1g
Date Posted: 07/02/2017 at 1:41am
I have tried this. Again not 100% but I did the same test with a Pixel XL (Android), Samsung S7 (Android), iPhone 6S and iPhone 7 and the readings were within 4 hz so nothing that would completely move a blade into a different category. ------------- --- http://mytabletennis.net/forum/forum_posts.asp?TID=71705&title=feeback-h0n1g" rel="nofollow - My Feedback Thread |
Posted By: zeio
Date Posted: 07/02/2017 at 4:03am
|
Here is modal analysis 101. An object has an infinite number of natural frequencies. With each natural frequency there is a corresponding mode shape, collectively known as the mode of vibration. The physical properties such as the mass, shape, and stiffness of an object dictate the frequencies it will vibrate at. In modal analysis, an impact test would be performed on an object to observe its modes of vibration. The object would respond(resonate) to frequencies that correspond to its natural frequencies. The duration of impact(contact time) characterizes the frequency content of the input force. Thus, an ideal input is one that has the shortest duration, and with enough force, which would generate a constant response across the entire range. In real world tests, an impact hammer is carefully chosen to excite only the frequencies of interest in order to reduce noise. For table tennis, the ball is the best impact hammer as it simulates real-world situations. A 1ms impact(the typical dwelltime for blade+rubbers) would excite modes below 1kHz, .5ms for those below 2kHz and so on. The wave generated by the impact would travel across and reflect within the boundaries of the blade. The lower end of the frequencies is responsible for both blade head and handle vibration and thus a lot of it would get absorbed by the hand. The upper end has more to do with just the blade head vibration and would travel away as sound. As to why a combo blade would give a similar response on both sides. The frequency response of an object is constrained by its entire construction. As the mechanical wave will traverse the blade, one can't expect one side to not get affected by the other. This is the reason why a symmetrical blade with the same rubber on one side would feel different when the other side is paired with a different rubber. ------------- 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 |
Posted By: vvk1
Date Posted: 07/02/2017 at 6:10am
Something feels a bit off with the latest table. Ebenholtz NCT VII is not slower than Ebenholtz NCT V or Ma Lin Soft Carbon. |
Posted By: JacekGM
Date Posted: 07/02/2017 at 1:07pm
Ok, this does strike a cord... ------------- (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. |
Posted By: DonnOlsen
Date Posted: 07/02/2017 at 4:26pm
|
I was wondering if it would be instructive to add to the Table Tennis Blade Frequency (Speed) Compendium a column of the manufacturers' rating of each of the blades. Something of interest may be revealed. Thanks.......... ------------- Tenergy: Two weeks of heaven, followed by three months of excellence, then, a nice rubber. |
Posted By: h0n1g
Date Posted: 07/03/2017 at 4:39pm
|
never mind, i copied the wrong cell.
------------- --- http://mytabletennis.net/forum/forum_posts.asp?TID=71705&title=feeback-h0n1g" rel="nofollow - My Feedback Thread |
Posted By: NextLevel
Date Posted: 07/03/2017 at 5:42pm
With the specific app slevin recommended, this is not a problem. At least, not AFAIK. ------------- https://youtu.be/jhO4K_yFhh8?t=115" rel="nofollow - I like putting heavy topspin on the ball... Cybershape Carbon FH/BH: H3P 41D. Lumberjack TT, not for lovers of beautiful strokes. No time to train... |
Posted By: book4all
Date Posted: 07/03/2017 at 8:04pm
|
Posted By: h0n1g
Date Posted: 07/03/2017 at 8:46pm
|
Got an ITC Premier XR ST today, 90g heavy, clocking in at 1442. ------------- --- http://mytabletennis.net/forum/forum_posts.asp?TID=71705&title=feeback-h0n1g" rel="nofollow - My Feedback Thread |
Posted By: h0n1g
Date Posted: 07/03/2017 at 9:26pm
|
The comparison table can now be reached at http://www.ttbla.de" rel="nofollow - www.ttbla.de ------------- --- http://mytabletennis.net/forum/forum_posts.asp?TID=71705&title=feeback-h0n1g" rel="nofollow - My Feedback Thread |
Posted By: arg0
Date Posted: 07/04/2017 at 12:47am
|
h0n1g, thanks for your efforts. Please fix your "Popular Blade Averages" section: you're averaging some totally unrelated data. Better calculate the averages (or medians) once and report the value. Or, use a find function to find data in the table, but in this case you have to take care of spelling/model variations (like "Violin L-Size") or ("M. Maze", "M.Maze", "Michael Maze", "Boll Spirit", "Timo Boll Spirit", etc.). ------------- Nexy Arche & Nittaku Violin LG. Join the forum_posts.asp?TID=47778" rel="nofollow - Nexy Clan ! Also member of Violin & 1-Ply clans. |
Posted By: AndySmith
Date Posted: 07/04/2017 at 7:23am
ITC Premier XF, FL, 91g, 1399 ITC Premier XF, ST, 90g, 1356 Gewo Zoom Balance ALL+, ST, 92g, 1464 Gewo Zoom Balance ALL+, ST, 91g, 1421 Hmmmm.
------------- This was a great signature until I realised it was overrated. |
Posted By: NextLevel
Date Posted: 07/04/2017 at 10:37am
Are you holding the blade too tight? Those are offensive blade scores. ------------- https://youtu.be/jhO4K_yFhh8?t=115" rel="nofollow - I like putting heavy topspin on the ball... Cybershape Carbon FH/BH: H3P 41D. Lumberjack TT, not for lovers of beautiful strokes. No time to train... |
Posted By: h0n1g
Date Posted: 07/04/2017 at 11:40am
Those numbers are indeed very weird. Are you able to run them again? ------------- --- http://mytabletennis.net/forum/forum_posts.asp?TID=71705&title=feeback-h0n1g" rel="nofollow - My Feedback Thread |
Posted By: Hozuki
Date Posted: 07/04/2017 at 12:19pm
|
Not so weird. I have already shown an inherent flaw in this method, which provides one possible explanation for this occurence, but nobody seemed to care. To see whether it applies to this specific case, the full frequency chart is neccessary, though. I'll make one more attempt at explaning it in more detail. Blades can vibrate in multiple frequencies that can be very close together in terms of pitch and volume. This is especially evident in ALL+ Blades. Here is an example: (Hinotec ALL+)  Now I ask you: Which frequency would you pick to insert into the table? 1005? 1500? Or 12000? As you can easily see, there is good potential for confusion. In fact, the first two peak freqs only have a 0.3 db difference in volume. Thus, a slight variation in blade weight, phone mic freq response or some other factor might lead to big differences between measurements of different people. So what can we do to make things more accurate? Easy. Just don't rely on a single indicator that condenses the frequency chart into one freq peak number. Either find a better one, or use multiple indicators. Based on this, we can now all start thinking what would be suitable. But I might be wrong since NextLevel said this issue does not matter since we all use the same app for recording. At least as far as he knows. So either he has better and more relevant information than I do, or... |
Posted By: h0n1g
Date Posted: 07/04/2017 at 12:21pm
|
The right frequency to pick is 1005 since it's the highest point vs amplification. Not sure what's confusing about that. That is why slevin suggested a program with peak hold, so you don't have the inconveniences of need to scroll through and endless graph. ------------- --- http://mytabletennis.net/forum/forum_posts.asp?TID=71705&title=feeback-h0n1g" rel="nofollow - My Feedback Thread |
Posted By: AndySmith
Date Posted: 07/04/2017 at 12:30pm
I tried to hold the blade as softly as I could, and only by the handle (not the blade face at any point). Although I did say in my initial review of the Zoom Balance that it was faster than I had expected an allround blade to be. But still, the numbers are high. ------------- This was a great signature until I realised it was overrated. |
Posted By: NextLevel
Date Posted: 07/04/2017 at 1:02pm
|
How thick is the blade? I do have my usual fingers on the blade face but I suspect that doesn't matter as long as you don't grip it as if it is in a vice. I could not play with a blade that fast comfortably hence my surprisr. ------------- https://youtu.be/jhO4K_yFhh8?t=115" rel="nofollow - I like putting heavy topspin on the ball... Cybershape Carbon FH/BH: H3P 41D. Lumberjack TT, not for lovers of beautiful strokes. No time to train... |
Posted By: AndySmith
Date Posted: 07/04/2017 at 1:17pm
Thickness is 6.2mm. It blatantly isn't that fast in the real world so something must be off somewhere. I'll try different balls and different mobile phones. I did the test with xiom seamless and my Oneplus One. ------------- This was a great signature until I realised it was overrated. |
Posted By: h0n1g
Date Posted: 07/04/2017 at 2:54pm
Whats especially surprising to me are the XF numbers being SO close to the XR (1400 vs 1450) ------------- --- http://mytabletennis.net/forum/forum_posts.asp?TID=71705&title=feeback-h0n1g" rel="nofollow - My Feedback Thread |
Posted By: h0n1g
Date Posted: 07/04/2017 at 3:37pm
|
So i wanted to check some things today and booted up Audacity and connected my Yeti Blue Snowball Mic (http://www.bluemic.com/products/snowball/), which is regarded as a pretty precise mic for its price-range. I've measured a few blades that I recorded before using a Pixel XL (Android) phone. Here are the results: KJH - Android - 1378 KJH - Yeti - 1364 Variance: 1.0% TB ALC - Android - 1442 TB ALC - Yeti - 1429 Variance: 0.9% Xiom Vega Tour - Android - 1291 Xiom Vega Tour - Yeti - 1296 Variance: 0.4% Xiom Vega Pro - Android - 1399 Xiom Vega Pro - Yeti - 1385 Variance: 0.1% Nexy Zealot - Android - 1399 Nexy Zealot - Yeti - 1396 Variance: 0.2% ITC Premier XR - Android - 1442 ITC Premier XR - Yeti - 1437 Variance: 0.3% So I think its save to say that mobile phones offer a pretty precise result given this check. Does this 'scientifically proof' anything? No but it at least shows that the recording equipment does not majorly influence the results. I have also used different balls in this test (Nittaku P40+ and DHS D40+) and the results were practically the same.
------------- --- http://mytabletennis.net/forum/forum_posts.asp?TID=71705&title=feeback-h0n1g" rel="nofollow - My Feedback Thread |
Posted By: book4all
Date Posted: 07/04/2017 at 3:44pm
Looks good to me. 
|
Posted By: arg0
Date Posted: 07/04/2017 at 4:06pm
Slightly off-topic, but this link shows the shape of vibration modes for a tennis racket: http://www.acs.psu.edu/drussell/Demos/tennis/tennis-1.html" rel="nofollow - http://www.acs.psu.edu/drussell/Demos/tennis/tennis-1.html This still does not fully correspond to the shape of the vibration modes of a table tennis blade, because vibrations of the string bed and frame are analysed separately, but they are closer than those for the circular membrane. ------------- Nexy Arche & Nittaku Violin LG. Join the forum_posts.asp?TID=47778" rel="nofollow - Nexy Clan ! Also member of Violin & 1-Ply clans. |
Posted By: arg0
Date Posted: 07/04/2017 at 4:41pm
|
By means of this acoustic frequency analysis the eigenfrequencies (or frequencies of vibration modes) of the blade can be determined. However, these cannot be directly matched to blade speed. To know how fast a ball will travel after impact, one needs to determine how much of the incoming energy is transferred back to the ball, and how much is absorbed by the blade, instead. This is a separate parameter (damping) and needs to be determined experimentally. I've just started thinking about this. One could try to measure damping by how high (in %) the ball rebounds after impact (though I don't see an easy way to reliably measure this), or indirectly by analysing the decay of the sound after ball impact. Damping also reflects on the width of the frequency peaks, but given how messy the spectra are, it will not be possible to reliably measure the width of the peaks in the audio spectra. Analysing the decay time of the vibrations of a single ball impact is also not trivial, as I'll try to show in a next post. Any thoughts? ------------- Nexy Arche & Nittaku Violin LG. Join the forum_posts.asp?TID=47778" rel="nofollow - Nexy Clan ! Also member of Violin & 1-Ply clans. |
Posted By: Hozuki
Date Posted: 07/04/2017 at 5:18pm
Seriously, did you even try to read what I wrote? First of all, my chart IS the peak hold result of several bounces. Also, it's not an endless graph, in fact, I zoomed it in so it becomes more clear. Secondly, at some bounces, the lower freq had the higher amplitude, in some cases the higher freq had the higher amplitude. The difference in maximum amplitude is just 0.3 db. Do you have any idea how little that is? Nope, yet you still would confidently choose 1005 hz. No wonder the table is flawed with ppl like you around. Thirdly, only because YOU don't have much variance between measurements of your standalone mic and your phone, doesn't mean others won't. There is something called frequency response of microphones, which is never perfectly linear (the difference can be quite a few db, which would be pivotal in my mentioned case). But since you consider a 'snowball' microphone an adequate tool for objective measuring, you obviously have no idea what you are doing. But don't mind me, continue with whatever makes you happy. |
Posted By: arg0
Date Posted: 07/04/2017 at 5:21pm
|
Update: I don't have had the time to review all my posts below yet, but I have played again with Higgs and, after all, and despite being a 7-ply blade, my impression is that it is not a fast blade (though it's advertised as being fast). Actually, it's speed is not much higher than Violin's. Amplitude and frequency spectra of a single ball bounce in similar experimental conditions (amplitudes were normalised). The membrane modes of Nittaku Violin and Nexy Higgs have a similar frequency, though Higgs is considerably faster. The vibration amplitude of Higgs decays much faster than Violin. Yinhe T-7 and Tibhar Inca share a similar speed (I never played the two side-by-side, however from memory the T-7 is faster than Inca), and also a similar membrane mode frequencies. The vibration amplitude of T-7 decays much faster than Inca, though. The speed certainly does not reflect in the amplitude of the frequency peaks. Can anything be said about the amplitude decay rate?     ------------- Nexy Arche & Nittaku Violin LG. Join the forum_posts.asp?TID=47778" rel="nofollow - Nexy Clan ! Also member of Violin & 1-Ply clans. |
Posted By: Hozuki
Date Posted: 07/04/2017 at 5:39pm
|
Since the Nexy is a 7ply, it is probably stiffer than the 5ply. That backs up my claim: The shorter the decay, the stiffer the blade. Your observation that the Nexy faster is probably explained by the higher stiffness as well. Therefore I argue that comparing the frequencies of blades with a similar decay time can yield more accurate results in comparing their speed. |
Posted By: arg0
Date Posted: 07/04/2017 at 5:51pm
Is the Hinotek an all-Hinoki blade? If so, from experience and gut feeling I would pick 1500 Hz as the membrane mode, and 1005 Hz as a bending mode. The reason is that all multi-ply hinoki blades I measured (with the exception of Nexy Tamar), tend to have a membrane-mode frequency which is much higher than their speed class: compare with Bty Kiso Hinoki V, and TSP Hinoki Pure in http://mytabletennis.net/forum/forum_posts.asp?TID=38419&PID=986447&title=estimating-blade-stiffness-through-sound-recording#986447" rel="nofollow - my data (not all measurements in there are by me, but those are). I had a similar issue with Nittaku S-5 (all-spruce), which I returned without even testing because of the high frequency. So it must have to do with hinoki/spruce/conifer wood. As to the double peaks, I also had this a few times, especially for 1-ply blades (Nittaku Miyabi and American Hinoki Ancient Kauri), and could not decide. I would need to look at the frequency spectra again, but if in your case I picked 1500, I suppose that for consistency, I would have to pick the higher frequencies. As to whether and how those frequencies are related to speed, see my doubts in my previous posts. I suppose that for measuring blade speed we need some way to estimate the blade's elasticity/damping index (to use a simplified name). And most likely we'd have to do this for low speed and high speed impacts, to take non-linearities into account. Not easy to do by hand, a ball cannon would be more appropriate... My impression is that these vibration mode frequencies are more related to the stiffness feel of the blade, than plain speed. Just, it often happens that the stiffer blades are also the faster. Or, if they somehow represent speed, by the way we obtain these frequency, by just dropping the ball on the blade, they can at most represent speed of the blade at low impact speed. It's late here and I cannot perform this test without waking my son, but anyone can make a quick test to see whether the frequency of the main peak varies by just dropping a ball on the blade or by hitting a ball as hard as you can with the blade? Try to grip the blade with the same strength in both cases. Or better yet, grip the blade with low force and record the sounds of: 1) a ball dropped on the blade while you hold it losely, and 2) the same ball being driven very fast on the blade by someone while you hold it losely, if that makes sense. ------------- Nexy Arche & Nittaku Violin LG. Join the forum_posts.asp?TID=47778" rel="nofollow - Nexy Clan ! Also member of Violin & 1-Ply clans. |
Posted By: Baal
Date Posted: 07/04/2017 at 5:56pm
Interesting point again about the decay. I wonder if we can do much other than show the whole spectrum? |
Posted By: Hozuki
Date Posted: 07/04/2017 at 6:15pm
|
Those are some good points you make, arg0. Some comments: The Hinotec just has Hinoki outer plies. But it might indeed be the special attribute of hinoki that leads to this second peak. How this affects speed, we can't say yet. I also think it would be very helpful to measure blade frequency response at high impact, and see what changes in the frequency chart occur. For more accurate results, the elasticity / stiffness would indeed also need to be considered. Maybe we can even approximate this by dividing the peak frequency through the decay time, as the stiffer blade feels faster (at least from low to medium impact) even if freq are the same, which can be corrected by such a formula. |
Posted By: Baal
Date Posted: 07/04/2017 at 6:21pm
Some practical considerations. Whatever you come up with has to be robust (for example not too sensitive to phone microphone variation), reproducible, and easy enough to implement that non-engineers can do it. That way it can be generally adopted. If only a small handful of people on these forums have the technical expertise to do this, it can never catch on. It might be ok to sacrifice a little accuracy if you can get that. Hopefully we can get something that can be useful to compare different blades within a class of bades (so it might not be a problem if you can't compare a 5-ply ALL+ wood with an OFF+ ALC blade because nobody really needs to do that). |
Posted By: arg0
Date Posted: 07/04/2017 at 6:48pm
|
Simply and robustly estimating decay time is not simple. We could try to use HWHH (Half-Width at Half-Height) as decay time, but that's still requires human intervention and will lead to human error, unless we find an automated way to do this: I suppose that fitting an exponential function to the audio amplitude may do the trick. Then again, we're not even sure how decay time influences speed, and we would need to have a mechanical model or experimentally validate any formula we come up with, or otherwise it's just guesswork. Another suggestion. Put a yardstick against a wall, and drop a ball from 1m height (or any suitable imperial length) on the blade and see how high it bounces. I imagine a layman gets about 10% error in the measurement, a tt player 5% ;-) This allows to determine how much energy is absorbed by the blade or lost by friction with air and how much returned to the ball. To factor air resistance out, since working in vacuum is not an option for many, we could use tiny stainless steel balls (e.g., from small ball bearings), but not everyone has some laying around. In alternative, you're only allowed to do this test at sea level :-D. Then again, tests would need to be performed to compare low-speed and high-speed impact. If we want to go down this road, better build some professional testing equipment somewhere and collect money to ship blades to the facility and back to their owners... Or, let's stay simple and let's see how far we can go with just a racket, a ball, a yardstick and a smartphone. ------------- Nexy Arche & Nittaku Violin LG. Join the forum_posts.asp?TID=47778" rel="nofollow - Nexy Clan ! Also member of Violin & 1-Ply clans. |
Posted By: arg0
Date Posted: 07/04/2017 at 6:55pm
|
The alternative is that people record their audio data and share the audio files so that some volunteer can analyse them. Anyone willing to create a public repository? Also, all the relevant data should be in the file name. What about Stiga _ Offensive Classic Carbon _ 82g (any other comment).mp3 or the like? Mp3 is just an example, any other audio format will be fine, as supported by your recording devices. Edit: I'm not volunteering myself  ------------- Nexy Arche & Nittaku Violin LG. Join the forum_posts.asp?TID=47778" rel="nofollow - Nexy Clan ! Also member of Violin & 1-Ply clans. |
Posted By: book4all
Date Posted: 07/04/2017 at 7:57pm
|
Just send all blades to one people to record and analyze the results. It is more accurate and consistent. Notes: I'm not volunteering myself . |
Posted By: slevin
Date Posted: 07/27/2017 at 2:27pm
From the latter part of http://en.butterflymag.com/2015/11/blade-with-a-soul/" rel="nofollow - this Butterfly article - I'm assuming Butterfly started using a similar version of this concept to express the relative speeds of its blades:Exact measurements produce exact values for blades http://www.butterflymag.com/wp-content/uploads/2015/11/Mitsuru-HAYASE.png" rel="nofollow">  Mitsuru HAYASE 2015, Butterfly introduced the “reaction” and “vibration” property as means to quantify the characteristics of a blade. What may seem like a minor change is actually a major switch in philosophy. Until now, blades have been charactized by a “speed” value into 5 categories (from All- to OFF+) and the feeling had to fit into 3 categories (soft, medium, hard). For example, the 5-ply “KORBEL” blade was characterized as “medium fast” with a “soft” feeling. These values were given as a result of testing and feedback from professional players. http://www.butterflymag.com/wp-content/uploads/2015/11/Vibrationswert.png" rel="nofollow">  Vibrationswert Mitsuru HAYASE, expert in fundamental research started to improve on this system 3 years ago:
------------- Trade feedback: http://mytabletennis.net/forum/forum_posts.asp?TID=50787" rel="nofollow - http://mytabletennis.net/forum/forum_posts.asp?TID=50787 |