Using a decibel met...
 
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Using a decibel meter with one gun and different attachments  

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sonnysan
(@sonnysan)
Joined: 2 years ago
Posts: 224
2020-03-22 16:30:54  

From the reviews, this $18 sound meter is 98% accurate vs. a $800 one, so I thought it would be a worthwhile exercise to try it out.

https://www.amazon.com/gp/product/B00ECCZWWI/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

The meter gives readings in real time, so you either watch the screen or press the min/max placed at a distance.  I elected the former due to a serious lack of time.

Test gun was a 50ft. lb. air ranger.  I did not get chrony numbers. 

Tried three different mods with the gun in my right hand, and the meter in my left.

Huggett:  96.6 db

Custom (Came from another Air Ranger purchase):  98.7db

Donny Tatsu:  101.5db

Did not have a Ronin on me, but I'm curious how more effective this attachment is vs. the rest.

Even tried an RX-1:  106.9db

There are so many variables, but I wonder what the "backyard friendly" db threshold is.

Examples:

https://www.noisehelp.com/noise-level-chart.html

 

 

 

 


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marflow
(@marflow)
Joined: 2 years ago
Posts: 746
2020-03-22 23:14:56  

i did some testing indoors but with that you have the pellet smack to deal with, so i used some cloth just free hanging so it would be as quite as possible 

so first you have to have a base line to compare against, so i bought a Paris D model 

small hallway, same sort of tester, background noise around 48 db, meter ahead of barrel 2 ft and was testing a Webley Alecto short barrel 

bare barrel 105 to 107  and good LDC in the 86 db range 

 

just my findings 


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Doug Wall
(@doug-wall)
Joined: 2 years ago
Posts: 129
2020-03-23 07:43:06  

I looked at the specs on the meter. It appears to be a "A" weighted meter. You really need a "C" weighted meter to accurately measure impulse noise. (A "Z" weighted meter would be even better, but that's big$$.) Looks like this one is giving you OK relative data, but don't write it down in a bible.

https://www.sciencedirect.com/topics/engineering/c-weighting


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marflow
(@marflow)
Joined: 2 years ago
Posts: 746
2020-03-23 15:22:58  

but we are not writing a scientific paper but just comparing LDC's in an informal setting

but in doing so we are collecting data that we can use and we are the end user 

it would be very hard for to duplicate informal testing in two place and have those number be the same no less, 2 people, 2 environments, different but similar sound meters 

but what they do is show us, is a picture of how well the LDC work in comparison 

and for me i'll take it 


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straitflite
(@straitflite)
Joined: 2 years ago
Posts: 154
2020-03-24 05:08:49  

but we are not writing a scientific paper but just comparing LDC's in an informal setting

but in doing so we are collecting data that we can use and we are the end user 

it would be very hard for to duplicate informal testing in two place and have those number be the same no less, 2 people, 2 environments, different but similar sound meters 

but what they do is show us, is a picture of how well the LDC work in comparison 

and for me i'll take it

I think so too. Much like one chrony can vary to the next, at least we can see differences in using the same one for a benchmark.

I may pick up one of those for that price. If several of us could afford the same model, we could have more common grounds for discussion of several guns, especially if the same rules were applied when testing.

The vendor lists them as low medium and high which is pretty vague considering all the different guns out there. I think they (vendors) should take the time to do actual readings for every gun they sell as this is important info for the majority of us. You know, obligate themselves to offer more knowledge on db's. Straight Shooters used to do an "our take" using 2 Ohlers 50yards apart for calculating BC's, ME's etc. Valuable information even if you get a gun with different values, it still paints a picture. You can still find those "our take" on gun model and caliber. Wish they would have used db's as well but what they did had to be a lot of work for us.

I'll take it too.


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Hector J Medina G
(@hector-j-medina-g)
Member of Trade
Joined: 2 years ago
Posts: 377
2020-03-24 13:40:31  

This is the one I use, while in use:

 

You can read more here:

https://www.gatewaytoairguns.org/GTA/index.php?topic=170803.msg155919410#msg155919410  

Note the weighing is "C" , and also note that response is set to "Fast"

Using "A" scale or response times that are too long, may yield VERY funny results. Specially if you want to compare the REAL noise levels of PCP's and Piston guns at the same time.

It has Max and Min function, and has worked well for many years. No longer available.

It has "scales" so the limit function helps on the accuracy side keeping it to ± ½ dB. A big thing because every 3dB is actually a relation of TWO (either doubling, or halving). So an accuracy of 1.5 is a BIG GAP.

"A" weighing is for music, not noise.

Backyard friendly depends on the size of your backyard.

I measure at 1 M distance PERPENDICULAR & IN LINE with the muzzle in OPEN AIR. ANY enclosure will skew the results.

At 108 dB's it takes 30 yards for sound pressure to go down to a normal conversation volume level (about 70 dB).

Double glazed windows have a Sound Attenuation value of 20-25 dB's, so you also need to take into account if your neighbours are inside or outside.

The rifle in question, a full power (20--> 24 ft-lbs in 020" cal D54) produced 128 dB's with a bare muzzle; with a reflex unit, it produced the shown 108 dB, so reduction was 20 dB's.
The Reflex unit only adds 1.5" to the OAL length of the gun and keeps the balance identical to what the OEM gun had.

HTH

 

 

 

 

 

HM

 

 

image

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marflow
(@marflow)
Joined: 2 years ago
Posts: 746
2020-03-24 15:45:32  

well the all measure sound, noise is a sound but the testing i did was to test sound 

2 things happened i saw a number on the meter and with my ears 

and did the same thing with a LDC and with that i saw a different number, lower and my ears told my the sound had diminished 

Hector i get the feeling that you talk down to us 

sure you know more so what 

we are doing some none scientific testing for ourselves and that testing is gleaning information for US as the hobbyist 

 


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sonnysan
(@sonnysan)
Joined: 2 years ago
Posts: 224
2020-03-24 22:01:20  

After some thought, I have decided to measure the following distances to get an overall picture.  Measurements would be taken in a backyard:

1.  Reading at the shooter's head.

2.  Reading at the muzzle.

3.  Reading at the impact area.

4.  Reading at the fence line(s).

I'd love to get a reading at the pesky neighbor's porch who wants to call the cops on you, but 1-4 should good be a good starting point:


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straitflite
(@straitflite)
Joined: 2 years ago
Posts: 154
2020-03-26 07:40:35  

Could you please try a reading in open air with no structures near? I'm just curious and wanting to learn more. If you have already done this, please disregard.

Thanks!

Edit: I would be interested in seeing the results you get with the Theobens and RX's and R1 97's etc. Having so many guns I realize this may be asking too much. The picture you paint would be very valuable info, however. It doesn't seem like anyone else is offering any 'realtime' input; Just opinions. Some of that may be important as well though. IIRC for example, 3db down as applied to electronics, is 70.7% of a given signal.

Ok, I'm going to now get off my butt and go shopping for one. Actually, I can do that sitting down too 😀 


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straitflite
(@straitflite)
Joined: 2 years ago
Posts: 154
2020-03-26 12:45:20  

I went ahead and bought this one:

https://www.amazon.com/VLIKE-Digital-Measurement-Frequency-Weighting/dp/B071J17TKL/ref=sr_1_5?keywords=c+weighted+db+meter&qid=1585239578&s=industrial&sr=1-5

It says it is ANSI spec'ed. After actually reading the article you linked Sonny, it seems like A is good enough for impulse sounds.

The one I got shows the meter's accuracy within different bandwidths in the ad but it looks to have the same accuracy as that less expensive one. Oh well, something to play with in different ways. I only have a few guns on hand to experiment with but I'll post on what I come up with when I get time down the road.


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