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TPX Stiffi v Stock barrel accuracy test


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#1 brycelarson

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Posted 21 September 2009 - 02:43 PM

At the request of KC from Stiffi I shot the Stiffi TPX barrel and the stock barrel.

here's the data sheet:
http://spreadsheets....GRg&output=html

and here's the video of the test:


The Stiffi barrel weighs in at a tiny 36g and looks really cool. As has happened in every other barrel test we've done - there wasn't a statistical difference in accuracy between the barrels.

Really want to thank KC and Stiffi on this one. It's really great that a company has the balls to willingly send us stuff to beat on. It really shows that they stand behind their work. They approached us. I wish that more companies were as willing to step up in this way.

Disclaimer - the barrel used in this test will not be kept or sold by PunkWorks or anyone related to PunkWorks. It will be given away.

#2 PacosTacos88

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Posted 21 September 2009 - 02:50 PM

First!

Can I haz barrel? :)

9571786023_b75503e9e4.jpg


#3 Pearlsea

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Posted 21 September 2009 - 02:54 PM

No I can has barrel for my awesome proposal of testing how paintballs would perform in a vacuum we will be colonizing the moon sooner then we thing and I think its a valid experiment so we know we can still shoot each other with gelatin on the moon when we have to abandon the earth in the aftermath of a nuclear world war.

Sooner then we think!
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[02:08:06] <@Kitty> hey pearl
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[02:08:26] * Pearl /wrists

#4 Spitlebug

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Posted 21 September 2009 - 03:03 PM

I love the sped up footage! It's actually quite interesting to watch.

So tempted to suspend Kitty just so I can say I have....
Okay, fuck it....I just banned Kitty, that's going in the sig.

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#5 brycelarson

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Posted 21 September 2009 - 03:08 PM

I love the sped up footage! It's actually quite interesting to watch.


do you like the part where my dog was trying to fetch the paintballs?

#6 Leafy

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Posted 21 September 2009 - 03:28 PM

wow thats strange how the, stock barrel is marginally better than the stiffi, of course thats within the range of error right?

#7 brycelarson

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Posted 21 September 2009 - 03:55 PM

wow thats strange how the, stock barrel is marginally better than the stiffi, of course thats within the range of error right?


Gordon can run the confidence intervals - but I don't think this is enough difference to say that one is better. Basically one winger could make this much difference.

#8 wilko

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Posted 21 September 2009 - 04:10 PM


wow thats strange how the, stock barrel is marginally better than the stiffi, of course thats within the range of error right?


Gordon can run the confidence intervals - but I don't think this is enough difference to say that one is better. Basically one winger could make this much difference.


But wouldn't a larger amount of shots increase the power of the results, therefore allowing for a bigger chance of the difference between the two barrels being statistically significant?
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#9 MondoMor

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Posted 21 September 2009 - 04:23 PM

Bryce, was this the barrel you had with the TPX on the day of the laning test?

Had I not been one digit off in the drawing for the TPX at Splat Tag yesterday, I'd be begging you for it. :)

#10 brycelarson

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Posted 21 September 2009 - 04:26 PM

But wouldn't a larger amount of shots increase the power of the results, therefore allowing for a bigger chance of the difference between the two barrels being statistically significant?


yes, the larger the sample size the smaller the confidence interval. In the types of statistical analysis we do 20 is really a magic number. It's large enough for the number to have real meaning - while not being so large that it makes the tests unwieldy. There is a diminishing return on sample size at some point. So, yes, in a test with an infinite sample size we could know exactly how the two things compare. Obviously that's not possible - which is what the confidence interval takes into account.

Having done a ton of these tests - without running the math myself - it looks to me that the difference isn't big enough in this case to be statistically significant.

....5 minutes later.

I just did a little poking around - I'll let Gordon show his work - but it looks to me like with a sample this size there would have to be a variance of somewhere between 1.2 and 2 between standard deviations in order to say with 95% certainty that one barrel is better. We're far less than that on this test. So, no, there is no statistical significant difference in accuracy between these barrels.

Bryce, was this the barrel you had with the TPX on the day of the laning test?

Had I not been one digit off in the drawing for the TPX at Splat Tag yesterday, I'd be begging you for it. :)


yup, this is it.

and we'll find a good reason to give it away. :)

#11 D.K.

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Posted 21 September 2009 - 04:55 PM

Bore of Stiffi TPX barrel?
Bore of Stock TPX barrel?
Average bore size of paint?

I actually was hoping(before I saw this thread) that you didn't do this test yet so you could do a decible test between carbon fiber and aluminum barrels.

#12 NovaPB

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Posted 21 September 2009 - 06:12 PM

Bore of Stiffi TPX barrel?
Bore of Stock TPX barrel?
Average bore size of paint?

I actually was hoping(before I saw this thread) that you didn't do this test yet so you could do a decible test between carbon fiber and aluminum barrels.


We demand decibel testing! If they don't effect accuracy, then the only thing barrels are good for is efficiency and reducing the sound signature of the marker.

P.S. You were not wearing goggles. And neither was your dog :)

Edited by NovaPB, 21 September 2009 - 06:13 PM.


#13 D.K.

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Posted 21 September 2009 - 06:20 PM

I was asking because the stiffi velocity numbers were less consistent.

#14 brycelarson

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Posted 21 September 2009 - 08:39 PM

dunno what the barrel bores were - I talked to KC and he couldn't remember if he sent me the 691 that was their standard - or ran a 689 for me. the stock TPX is 691 I think.

paint is large - snug in a phantom breech - so should be around 687/689.

for a paint to barrel match this gun is very consistent. It's basically a modern version of a mag valve - so it's really a great valve system.

I do own a SPL meter - I'll pull it out and do some barrels at some point.

#15 Lord Odin

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Posted 22 September 2009 - 08:16 AM

dunno what the barrel bores were - I talked to KC and he couldn't remember if he sent me the 691 that was their standard - or ran a 689 for me. the stock TPX is 691 I think.

paint is large - snug in a phantom breech - so should be around 687/689.

for a paint to barrel match this gun is very consistent. It's basically a modern version of a mag valve - so it's really a great valve system.

I do own a SPL meter - I'll pull it out and do some barrels at some point.


Wouldn't a spectrum analyzer program be better for the sound? I tried to do some SPL measuring before but everything came out the same, even though you could hear a noticeable difference in the sound.

#16 Leafy

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Posted 22 September 2009 - 08:19 AM


dunno what the barrel bores were - I talked to KC and he couldn't remember if he sent me the 691 that was their standard - or ran a 689 for me. the stock TPX is 691 I think.

paint is large - snug in a phantom breech - so should be around 687/689.

for a paint to barrel match this gun is very consistent. It's basically a modern version of a mag valve - so it's really a great valve system.

I do own a SPL meter - I'll pull it out and do some barrels at some point.


Wouldn't a spectrum analyzer program be better for the sound? I tried to do some SPL measuring before but everything came out the same, even though you could hear a noticeable difference in the sound.


there was some reason for this that I cant remember, I think it has to do with how the spl meter works, how it reads the pressure wave and not the sound or something.

#17 brycelarson

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Posted 22 September 2009 - 08:55 AM

Wouldn't a spectrum analyzer program be better for the sound? I tried to do some SPL measuring before but everything came out the same, even though you could hear a noticeable difference in the sound.


I've got both. I just don't have a calibrated mic for my USB preamp. I can use the SPL meter to eyeball calibrate the computer I suppose. It won't be exact, but for our needs it should be fine. I'll look into this - sounds like a good winter project. I should be able to produce waterfall plots of volume at frequency. That would be a good descriptor of whether it's a thud or a smack sound.

#18 Troy

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Posted 22 September 2009 - 09:12 AM

At about 2:30 it looks like you ate one of the paintballs... thats disgusting, lol
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#19 brycelarson

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Posted 22 September 2009 - 09:14 AM

At about 2:30 it looks like you ate one of the paintballs... thats disgusting, lol


gotta snack on something while I'm testing.

#20 Spitlebug

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Posted 22 September 2009 - 10:26 AM

do you like the part where my dog was trying to fetch the paintballs?


I saw that, your puppy seems like quite the character.

So tempted to suspend Kitty just so I can say I have....
Okay, fuck it....I just banned Kitty, that's going in the sig.

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#21 Lord Odin

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Posted 22 September 2009 - 12:40 PM


Wouldn't a spectrum analyzer program be better for the sound? I tried to do some SPL measuring before but everything came out the same, even though you could hear a noticeable difference in the sound.


I've got both. I just don't have a calibrated mic for my USB preamp. I can use the SPL meter to eyeball calibrate the computer I suppose. It won't be exact, but for our needs it should be fine. I'll look into this - sounds like a good winter project. I should be able to produce waterfall plots of volume at frequency. That would be a good descriptor of whether it's a thud or a smack sound.

Will doing it indoors cause any problems with sound reflections?

#22 Leafy

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Posted 22 September 2009 - 12:42 PM



Wouldn't a spectrum analyzer program be better for the sound? I tried to do some SPL measuring before but everything came out the same, even though you could hear a noticeable difference in the sound.


I've got both. I just don't have a calibrated mic for my USB preamp. I can use the SPL meter to eyeball calibrate the computer I suppose. It won't be exact, but for our needs it should be fine. I'll look into this - sounds like a good winter project. I should be able to produce waterfall plots of volume at frequency. That would be a good descriptor of whether it's a thud or a smack sound.

Will doing it indoors cause any problems with sound reflections?


I dont see it being that big of a difference, as long as he's in a big enough room with enough soft surfaces in it, ie not in an utilitarian bathroom.

#23 brycelarson

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Posted 22 September 2009 - 01:09 PM

Will doing it indoors cause any problems with sound reflections?


depends on what the test is trying to do. If the test is to give the real, calibrated SPL readings from guns - then yes, that's not going to happen in my house. You need to get into an anechoic chamber for that - and I don't happen to have one.

If the goal is simply to get comparable number from different barrels - then as long as the setup is repeatable it'll do just fine.

So, even given the bathroom example - as long as the measurements were taken in the same way from barrel to barrel, gun to gun etc. - then it'll give us a useful comparative number.

My thought was to do the test outdoors - to get as clean a signal as I can.

#24 UV Halo

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Posted 22 September 2009 - 04:11 PM

Is the Stiffi Barrel you tested ported? If not, I'm expecting that there will be a minimal sound level difference between the two barrels. Even if there is porting, The barrel is so short I'd be surprised if it turned out to be substantial.

#25 Deadpool

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Posted 22 September 2009 - 05:45 PM

I love the sped up footage! It's actually quite interesting to watch.


Yeah it looks like one of those Benny Hill movies... minus the "softlegs"



#26 Lord Odin

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Posted 22 September 2009 - 10:33 PM

Do humans interpret things as being louder based on frequency, dB, or a combo? For example, say one TPX barrel has a lower dB but different frequencies that make it more noticeable. Are there certain frequencies that humans will pick up on quicker than others? Which would we consider to be "louder"?

#27 Leafy

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Posted 22 September 2009 - 10:35 PM

frequency and dB. I think theres like a graph or something, also dont forget that high frequency is more directed but tends to travel further while low frequency tends to be more omni directional.

#28 brycelarson

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Posted 23 September 2009 - 07:59 AM

frequency and dB. I think theres like a graph or something, also dont forget that high frequency is more directed but tends to travel further while low frequency tends to be more omni directional.


right, there are actually things called weighting - most common are A and C.

A weighting accounts for the various sensitivities of human hearing - C weighting is more flat - outputting closer to the same volume at all frequencies.

The difference can be heard in Pink vs White noise. human ears are more sensitive to higher frequencies. White noise is C-weighted - so it sounds mostly like a hiss. Pink noise is A weighted so it has more rumble and "body" to the low end.

If you're measuring how loud something sounds - then A weighting is the way to go.

http://en.wikipedia....ting_curves.svg

Edited by brycelarson, 23 September 2009 - 07:59 AM.


#29 Spitlebug

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Posted 23 September 2009 - 10:46 AM

Yeah it looks like one of those Benny Hill movies... minus the "softlegs"


Yeah that's pretty close to what I was thinking. Not quite as entertaining as Bryce but here you have it:

http://www.youtube.com/watch?v=Hg3ccf9cnsg

So tempted to suspend Kitty just so I can say I have....
Okay, fuck it....I just banned Kitty, that's going in the sig.

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#30 pbplayer2327

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Posted 16 July 2010 - 10:20 PM

No I can has barrel for my awesome proposal of testing how paintballs would perform in a vacuum we will be colonizing the moon sooner then we thing and I think its a valid experiment so we know we can still shoot each other with gelatin on the moon when we have to abandon the earth in the aftermath of a nuclear world war.

Sooner then we think!



Alright way to think ahead dude






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