[jdlarson11]

jdlarson11, on 25 August 2010 - 07:16 PM, said:

Do you guys know the total decibel readings of each gun?

you can get close by estimating the center of the curve. I've got most of the curves saved individually. Which one you looking at?

I just want to know what the SR peak DB was atand how does that compare to a normal pistol (9mm/45)

This post has been edited by jdlarson11: 25 August 2010 - 08:43 PM

[brycelarson]

the test mic I'm using I made - so it's not calibrated. I've got an SPL meter - I can certainly check next time we do this.

[lovebunny]

im thinking a stock AKP is louder then the sr?

[brycelarson]

We'll test it.

[lovebunny]

brycelarson, on 26 August 2010 - 10:08 AM, said:

We'll test it.

a stock farting one?

ore a tuned one with a reg and the goodies?

[brycelarson]

I can slap the gas through back on it - but even with a reg it still farts exactly the same way.

[lovebunny]

brycelarson, on 26 August 2010 - 10:22 AM, said:

I can slap the gas through back on it - but even with a reg it still farts exactly the same way.

yeah it thous.. but keep it stock,
and hey trow in the reg and se if theres any diffrens

[chem daddy]

I wonder if your mic is picking up AC line noise. Allmost all the FFTs show a feature at ~60-63 Hz. Alot of times this is indicative of a ground loop pickup.

[brycelarson]

yeah, that's possible. We did have some without the feature at 60 hz, so I'm not sure. The other possibility is that it's a room reflection. A 60 hz wave should be about 15 feet long - and that would be about the distance from the gun past the trap into that alcove.

I use that system pretty regularly and it's normally very clean - but the power in my basement might be a bit sketchy - something I intend to re-do when I put the walls back.

[nwi.pballer32]

etek 3 sound test!!

[chem daddy]

Watching the first video again, It looks like the 60 Hz peak is also prominent when you are not shooting, leading me to be more confident that it is AC line noise. Did you guys do a background subtraction? That will probably remove most of the 60 Hz and give you the spectrum of sound due only to the marker firing.

I don't know that much about acoustics, but would integrating the FFT as a function of frequency give you an indication of overall loudness? This would give a single number to compair vs looking at the entire spectrum. (I may be totally off base here, let me know if I'm wrong)

I think what you guys are doing is great, working on the science behind paintball. So much in PB is vodoo & myth, it's good to see people testing things and thinking for themselves.

[cockerpunk]

indeed, i'd love to compute the area under the curve, but this software doesn't output pure data very well. thats the difference in an engineering software package and an audio-tech software package.

were working on a better method, but its hard to do. we'll see.

[brycelarson]

I can clarify things a bit. The microphone we're using isn't a calibrated mic. Those cost a few hundred bucks. This is a microphone I made that uses the same panasonic mic capsule used in most commercial test mics.

This mic may not represent exactly what the real curve of these guns - nor can it tell us actual db levels. It is very close. I've checked it against calibrated mics and it's within 3 db at pretty much the whole 20-20000 hz range. I have not checked the db reading against a calibrated mic. So, what this means is that this mic may not show exactly the correct frequency db level - BUT when we're using it to compare two signals it will give a very accurate comparison.

I do own a calibrated db meter - so we can certainly check some guns and post the raw db number.

and yeah, next time we set up I'll throw my phones on the preamp and take a listen. I've heard a lot of 60 hz hum in my day - it's very apparent.

I wouldn't look at that lump too much, human ears are really bad at locating and distinguishing low frequency sounds - the mid and high freq stuff is going to be WAY more important when talking about something like gun loudness.

[Lord Odin]

Have you guys tested loudeners? Flasc, Lapco, and Opsgear all make a dishka/cannonizer/loudener. Was wondering if a cone aimed towards the target or a wider cone makes it louder.

BTW, have you guys tested the sound signatures in front as well as off to the side?

[cockerpunk]

front and side test is on the list. we only have one loudener and thats the flasc.