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 Post subject: .22LR Subsonic dB's ?
PostPosted: Wed Jul 27, 2011 6:03 pm 
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Silent But Deadly
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Hi,

Does anyone knows or have data on how much dB’s a Subsonic .22LR meters (target impact blast not taken into account) ?

Best,

Paul

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 Post subject: Re: .22LR Subsonic dB's ?
PostPosted: Wed Jul 27, 2011 8:19 pm 
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PaulNoiseLess wrote:
Hi,

Does anyone knows or have data on how much dB’s a Subsonic .22LR meters (target impact blast not taken into account) ?

Best,

Paul

I do know that the Aguila 40 grn subsonic is one of the quietest but I'v never seen any data or db test on ammo but it would be nice
to have.
I'm thinking it would be diferent db's depending on the barrel length and gun the test was on. like auto action vs bolt action.


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 Post subject: Re: .22LR Subsonic dB's ?
PostPosted: Wed Jul 27, 2011 10:46 pm 
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Silencerresearch.com

150+ on a pistol, 140 on a rifle.

And as taz said, you're mileage may vary depending on action type and barrel length.

Gene


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 Post subject: Re: .22LR Subsonic dB's ?
PostPosted: Thu Jul 28, 2011 6:43 am 
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Hi,

Are these numbers suppressed or unsuppressed ?

Thanks,

Paul

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 Post subject: Re: .22LR Subsonic dB's ?
PostPosted: Thu Jul 28, 2011 7:25 am 
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Those are unsurppessed #'s. With a top tier can take away up to 41 or so db.

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 Post subject: Re: .22LR Subsonic dB's ?
PostPosted: Thu Jul 28, 2011 7:42 am 
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Hi,

OK, thanks. I went thru some reviews (old) in Silencerresearch.com and, yep !, looks like Suppressed subsonics are in the range of 110-120 dB.

I’m just trying to figure out if my new dB meter is going to be any useful for comparisons using subsonic ammo.

Find a Pic of what I’ve got so far. I don’t even know how it works. Any clue ?

Best,

Paul

Image

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 Post subject: Re: .22LR Subsonic dB's ?
PostPosted: Thu Jul 28, 2011 8:22 am 
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That looks like some sort of tool for the lady's at the doctors office :)
DB meter/smart sensor or Dumb Blonde meter :wink:


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 Post subject: Re: .22LR Subsonic dB's ?
PostPosted: Thu Jul 28, 2011 9:56 am 
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EBAY http://cgi.ebay.com/130dB-Digital-Sound ... 4cf8f38f20


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 Post subject: Re: .22LR Subsonic dB's ?
PostPosted: Thu Jul 28, 2011 2:50 pm 
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That will not capture a gun shot.. It is about the same as a Radio Shack Sound meter. (I have one for my home theater)

The rise time of a gunshot is so fast the meter will not capture the peak.

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 Post subject: Re: .22LR Subsonic dB's ?
PostPosted: Thu Jul 28, 2011 3:51 pm 
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You need a meter with at least a 20us rise time or faster new meters are to slow 30us-50.
and cost 5gs or more.
Much unsuppressed data can be had in the Paulson books.



pun intended.

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 Post subject: Re: .22LR Subsonic dB's ?
PostPosted: Fri Jul 29, 2011 6:28 am 
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we metered my marlin bolt action .22 at work with aguila 40 gr. subs. the barrel length is 16.25 in. it metered at 138.6 db un suppressed.


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 Post subject: Re: .22LR Subsonic dB's ?
PostPosted: Fri Jul 29, 2011 7:41 am 
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Hi,

OK, let’s figure out the following scenario (for all, same weather conditions):

1) I have measured 90 dB using a Pro dB meter (Rifle A (RA), Ammo A (AA), Location A (LA), Suppressor A (SA))
2) Now, I fire RA, AA, LA and SA and measure using the s--t dB meter I bought. I get 80 dB.

Questions when measuring with the s--t one:

1) If I fire RA,AA,LA and SB, I get 75 dB: Does it means SB is quieter than SA ?
2) If I fire RA,AB,LA and SB, I get 85 db: Does it means SB is louder using this ammo ?

Can I extrapolate dB numbers ?, ie: RA,AA,LA and SB = (75*90)/80 = 84,375 dB and RA,AB,LA and SB = (85*90)/80 = 95,625 dB

I’ve done little test with the s--t one and for sure it’s measuring something because I leave it alone and doesn’t move but when I actually have a shot it goes up and shows a MAX number (¿?).

I’m not looking for dB numbers but a way to know if a Suppressor is better or worse than other (comparing to a trusted one) so I can go beyond my hears and dogs to judge.

Best,

Paul

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 Post subject: Re: .22LR Subsonic dB's ?
PostPosted: Fri Jul 29, 2011 9:10 am 
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Yes, your assumptions are correct.

As far as your meter's ability goes, most will say that it's no good because it's not sensitive enough. I disagree. If you're not looking to compare with others, and only want a before and after, then your meter will likely do just fine.

Just because a microphone isn't fast enough to measure the full peak, it will still average out the peak. It's physics. The mic IS going to move, and it's going to move more for a louder noise. The caveat, is that it will also move more for a longer spike, like you whistling into the mic. But if you're only comparing apples to apples,.. .ie,.. silencer A to silencer B, then I think it's a valid test.

I'm not sure about your math. Just remember that db is exponential, so if you extrapolate, you need a curve.

Gene


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 Post subject: Re: .22LR Subsonic dB's ?
PostPosted: Fri Jul 29, 2011 12:10 pm 
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Read: http://www.sandv.com/downloads/0908rasm.pdf
You can't measure a mountains height by how wide it is at its base.

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 Post subject: Re: .22LR Subsonic dB's ?
PostPosted: Fri Jul 29, 2011 12:49 pm 
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Everyone thinks that once they have superior equipment, everyone with lesser equipment is doing absolutely no good. The folks in the article you mentioned have a very nice setup that smokes any of these cheap $5k meters that are typically used for silencers.

Did Paul's meter show him a difference between his silencers? Your analogy is nice, but my assertion stands. With both human ears, and electronics, things are pretty much averaged anyways.

A quote from that article that seems to me to suggest that the meters are averaging:

Often such signals may be analyzed using
A-weighting, exponential averaging or 1/3-octave filtering. This
will change the measured acoustic characteristics of the gun shot
impulse.
Figure 13 illustrates the effect of A-weighted filtering on the
time-based signal. A-weighting reduces the frequency content in
the original signal above 2 kHz; consequently, the peak level is
reduced from approximately 4000 Pa (166 dB peak) to 2200 Pa
(161 dB SPLpeak), or a reduction of about 5 dB. At the same time,
the finer details in the signal are lost. Further analyzing the signal with exponential averaging of a
sound level meter will also reduce the peak level and the pressure
details of the signal. The amount of reduction will depend on the
averaging time used in the measurement. With an exponential
averaging in “fast” mode corresponding to 125 msec averaging
time, the peak will be measured as 137 dB, and with an exponential
averaging in “impulse” mode corresponding to 35 msec averaging
time, the peak will be measured as 140 dB

End quote.


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 Post subject: Re: .22LR Subsonic dB's ?
PostPosted: Fri Jul 29, 2011 3:04 pm 
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Why is it so hard to understand
if you dont get all sound measured , you dont get all sound measured :wink: simple isnt it

a to slow meter will not measured the peak , and that IS what counts

he will be better of using his+ others ears

if a good meter would pick up a spike that was about hearing damaging levels ,, how would he know ??

so if its for that reason , he needs a good meter

if it is for how a human notices the sound (neighbor friendly)
dont use a meter at all ,, use ears
use them close up , and far away , depending what you wants to achieve

spend the money on tooling :wink:


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 Post subject: Re: .22LR Subsonic dB's ?
PostPosted: Fri Jul 29, 2011 3:12 pm 
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Paul nobody is picking on you,we are trying to educate you on why you can't make comparative studies with what you have.

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 Post subject: Re: .22LR Subsonic dB's ?
PostPosted: Fri Jul 29, 2011 4:52 pm 
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Hi,

Yes, OK; no offence at all on the comments. All of them are educational.

Now, I take a shot with Can A and the s--t measures 90. Take another shot with Can B and the s--t measures 100.

What does it means ?. I don’t really care about accurate Dbs, just want to know if B is louder than A.

And now, let me tell you what I need all this for: Tubeless Suppressors. They are modular (you can add/remove Baffles and spacers as you go). What I want to find out is the right configuration for each caliber tested. In other words, I want to know when adding Baffles is worthless or the impact on having bigger Blast. I’m going to use subsonics for all of them to skip sonic crack.

I’ll try anyway and Post the results so we try to find out what’s going on.

Best,

Paul

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 Post subject: Re: .22LR Subsonic dB's ?
PostPosted: Fri Jul 29, 2011 5:47 pm 
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[quote="PaulNoiseLess"]Hi,

Yes, OK; no offence at all on the comments. All of them are educational.

Now, I take a shot with Can A and the s--t measures 90. Take another shot with Can B and the s--t measures 100.

What does it means ?. I don’t really care about accurate Dbs, just want to know if B is louder than A.

You can't tell with the meter on hand. Look at it this way a gunshot lasts 5usec (time)your meter will not respond for lets say 50usec.By the time the meter responds the peak sound pressure level has already passed you are left measuring echos and gas escaping from the can.Your 100db measure may be more quite then the 90db as you may be measuring the time delay of the gas, or not.
A pair of ears will be more informative.

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 Post subject: Re: .22LR Subsonic dB's ?
PostPosted: Fri Jul 29, 2011 6:31 pm 
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Hi,

OK undertood. I'll try and if we don't see any consitent or usefull results, we'll enjoy blowing it up (I'll take a Vid on that) !

Best,

Paul

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