How to measure blade frequency?

[TensorBackhand]

I downloaded the Spectroid app as suggested, but I don't know really what I am looking for.

1) How hard am I supposed to bounce the ball on the blade? Does bouncing harder or softer make a difference in the frequency?

2) When I bounce the ball, I see a long wavy line from left to right. Where am I supposed to measure the frequency? at the peak of the wave?

 

[riemsesy]

I have an app Sonic Tools SVM that I can configure only to record the highest pitch measured. And only that is showed.
(installed it again, and it's a button [Peak Hold]
If you only see the live frequency it goes too fast.
Had to install a bunch of apps to finally find something that was free and showed the frequency measured.

 

[TensorBackhand]

I have an app that I can configure only to record the highest pitch measured. And only that is showed.
If you only see the live frequency it goes too fast.
Had to install a bunch of apps to finally find something that was free and showed the frequency measured.

which app do you recommend?

 

[TensorBackhand]

I tested a random blade and it shows 1230 at the peak here. Am i doing it right? Am I supposed to put the marker at the top of that red line?

 

[Lazer]

Yep the frequency’s with the highest peak.

What blade are you measuring?

Cheers
L-zr

 

[TensorBackhand]

How reliable is this frequency thing compared to the feeling and flex of the blade?

Since I have some new blades coming in: I was thinking maybe I test the frequency and if it is too high/too stiff then I just return the blade.

 

[TensorBackhand]

Yep the frequency’s with the highest peak.

What blade are you measuring?

Cheers
L-zr

Sportcraft, short pips. Should i add this to the spreadsheet?

 

[Lazer]

View attachment 33121


Sportcraft, short pips. Should i add this to the spreadsheet?

Now if you have a rubber on, the frequency will change. But it’s ok to play around I guess…

Cheers
L-zr

 

[JustANoob]

Knock on it like checking a watermelon.

If the sound is dull when hitting the ball it will go piuu so it needs to ripen some more. If its a sharp sound the ball will go whiuiuiui so its just right for playing.

 

[TensorBackhand]

Table Tennis Blade Frequency (Speed) Compendium

docs.google.com

How reliable is this frequency thing actually? I see F3 Pro recorded as 1500. But my F3 Pro was by far my softest, flexiest blade.

 

[RefereeNumber2]

The highest-peak (loudest) frequency is related to the membrane vibration mode of the blade's head. My understanding is this is more directly related to the "hardness" or "sharpness" of the blade feeling than its speed/elasticity per se, although it's correlated with elasticity.

The frequency can be affected by physical contact with the blade, e.g., how tightly you grip it (and definitely if there are rubbers still attached). When I'm measuring a blade's frequency I make sure I always balance the blade's handle across two fingers to be as consistent as possible. One way to test it yourself is to see if you can get the same exact (within a few Hz) measurement multiple times with the same blade. The membrane frequency is a physical property of the blade so if you're getting different measurements then something else is changing (probably grip tightness).

 

[Tiz]

I'm using an app called Decibel X for Iphone. It automatically highlights the peak

 

[TensorBackhand]

I'm using an app called Decibel X for Iphone. It automatically highlights the peak

is it free?

 

[Tiz]

is it free?

Yes, there are in-app purchases available but you don't need them for this task.

 

[Lazer]

Table Tennis Blade Frequency (Speed) Compendium

docs.google.com

How reliable is this frequency thing actually? I see F3 Pro recorded as 1500. But my F3 Pro was by far my softest, flexiest blade.

As far as speed goes, no so much. As far as hardness a little better. but it depends on the construction .

1500 doesn’t sound right. But it comes down to construction….

Cheers
L-zr

 

[TensorBackhand]

As far as speed goes, no so much. As far as hardness a little better. but it depends on the construction .

1500 doesn’t sound right. But it comes down to construction….

Cheers
L-zr

So I ordered Pro 01 and Pro 03, I'm hoping both to be under 1400. Above 1400 sounds like we are getting into brick territory.

 

[Lazer]

So I ordered Pro 01 and Pro 03, I'm hoping both to be under 1400. Above 1400 sounds like we are getting into brick territory.

That’s ways past brick territory for me. I’m thinking more like 1250 -1300. But then again it’s down to construction…

Cheers
L-zr

 

[Loop Lob Smash]

Knock on it like checking a watermelon.

If the sound is dull when hitting the ball it will go piuu so it needs to ripen some more. If its a sharp sound the ball will go whiuiuiui so its just right for playing.

 

[turbozed]

You can try using Advanced Spectrum Analyzer PRO if you got Android (it's free to use).

1. Top right of app tap on option to"Enable peak hold"
2. Bounce ball on empty blade
3. Hit pause.
4. It'll show you the curve of the highest frequency achieved. Drag along the line and get to the first peak.

Sanwei 75 Inner was around 1400 hz too. Sanwei Fextra was around 1313 hz to 1336 hz. Nittaku Acoustic Inner was 1313 hz. Stuor Harimoto was 1421 hz.

I don't think the frequencies accounts for the flex of the blade much, and it's more of a measure of the hardness of the material composition. Because we're just bouncing the ball on a naked blade, the force is small and the impact point is smaller, which doesn't really resemble actual play at all.

With the rubbers on, and on harder hits or counters, the force is multipled by many fold and the impact force is spread out over a wider surface area since it's absorbed then transferred through the rubber. This is when the flex of the blade will come into play and why one 1400 hz blade may feel much softer than another.

For example, my Fextra feels way more stiff and less soft than the Acoustic NAIC in gameplay (especially blocks) despite being the same hardness. Makes sense as it's way thinner (5.5 mm vs 6.0mm) so on many shots the blade will flex and this will soften the feel.

With that in mind, it's debatable how useful measuring frequencies like this really is. Some people may be sensitive or advanced enough to discern between the softness of the impact point versus the overall 'softness' of the blade feeling. I certainly can't.

 

[haggisv]

With that in mind, it's debatable how useful measuring frequencies like this really is. Some people may be sensitive or advanced enough to discern between the softness of the impact point versus the overall 'softness' of the blade feeling. I certainly can't.

I agree completely. It can provide some valuable information when comparing similar blades (tested by the same person and method), but it's difficult to turn the values into useful characteristics and you can actually experience. Certain constructions also give values that are way off the expected range of range, e.g. Balsa or 1-ply blades, so be careful how you interpret the values.

I see this tool mainly useful for blade designers, who have proper equipment and standard testing procedures, and can use it to tweak certain characteristics,