GTA
All Springer/NP/PCP Air Gun Discussion General => PCP/CO2/HPA Air Gun Gates "The Darkside" => Topic started by: mrbulk on October 23, 2020, 02:48:39 AM
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With the addition of a couple more name-brand LDCs, I re-compared their loudness with a basic (cheap) sound meter from a fixed distance. All of the LDCs were fired through with the same gun, in this case an Avenger .22 w/reg set at 1800psi and hammer spring turned inward 2.75 rotations.
At these settings the JSB .22 18.13-gr diabolos were averaging in the mid-800s fps with over 90 useful shots. Close to 30 FPE and definitely not backyard friendly without an LDC.
For this test the gun was fired downrange into a duct seal silent trap using the same JSB 18.13-gr pellets, and the decibel meter was placed even with the muzzle and 6 feet off to one side. The following comparisons are broken down by category.
Sorted by dB:
83.40 DonnyFL Sumo
83.57 Huma 40mm Std
84.40 STO Falx
84.63 DonnyFL Tanto
85.17 Rocker1
85.63 Geo Long
85.70 Neil Clague
85.93 Geo Short
86.33 TKO Slim
87.57 Zero DB 110C
87.57 Wolf 35mm
88.43 Wolf 30mm
98.83 Bare Barrel
Sorted by COST ($):
27 Geo Short
29 Geo Long
49 Wolf 30mm
59 Wolf 35mm
65 Rocker1
92 TKO Slim
99 DonnyFL Tanto
120 Zero DB 110C
129 STO Falx
135 N Clague
150 DonnyFL Sumo
160 Huma 40mm Std
Sorted by VOLUME (cu. in. calculated from ext. dimensions):
5.11 Rocker1
5.25 TKO Slim
5.68 Zero DB 110C
6.02 DonnyFL Tanto
6.06 Geo Short
7.68 Geo Long
8.32 Wolf 30mm
11.25 Wolf 35mm
12.10 DonnyFL Sumo
12.70 STO Falx
12.88 Neil Clague
14.14 Huma 40mm Std
Sorted by WEIGHT (oz.):
1.7 Geo Short
2.3 Geo Long
2.9 TKO Slim
3.3 Rocker1
3.5 Zero DB 110C
3.8 DonnyFL Tanto
4.7 Wolf 30mm
5.9 DonnyFL Sumo
5.9 Neil Clague
6.4 STO Falx
6.6 Wolf 35mm
7.6 Huma 40mm Std
Actual Meter Readings: (High to Low):
Bare Bbl- 99.0/98.7/98.8 (98.83 avg)
Wolf 30- 88.7/88.4/88.2 (88.43 avg)
Wolf 35- 86.9/87.8/88.0 (87.57 avg)
Zero DB- 88.0/87.6/87.1 (87.57 avg)
TKO Slim- 85.7/86.5/86.8 (86.33 avg)
Geo Shrt- 85.5/85.8/86.5 (85.93 avg)
Neil Clague- 85.9/85.2/86.0 (85.7 avg)
Geo Long- 85.9/85.5/85.5 (85.63 avg)
Rocker1- 85.7/84.8/85.0 (85.17 avg)
Tanto- 84.7/84.2/85.0 (84.63 avg)
STO Falx- 83.7/84.9/84.6 (84.4 avg)
Huma- 83.3/84.2/83.2 (83.57 avg)
Sumo- 82.9/83.8/83.5 (83.4 avg)
Feel free to compare these units via the different categories but keep in mind that some units, although not the best in any one measurement, came off looking pretty good by placing in the top five of every category. For example, look at the slim and lightweight Rocker1. 8)
And the Sumo finally beat its little brother now that pellets were actually fired through the LDCs. In fact the Sumo beat everything in the dB category.
It should be said that the larger units, through sheer volume, may handle even higher-powered guns better than the smaller units, and thus results may differ from this specific test. The above comparisons are for these particular units on this day with this gun in its current tune shooting this ammo at today’s temperature, barometer, humidity and other associated weather conditions. And maybe even what phase the moon was in.
Also the sound deadening effect is notably dramatic going from bare barrel to any LDC. Even the loudest unit, the Polish Wolf 30mm, was noticeably quieter than the bare barrel. It should be remembered that on the decibel scale, doubling the intensity corresponds to an increase of 3 dB. This does not correspond to a perceived doubling of loudness, however. We perceive loudness to be doubled when the intensity increases by a factor of 10, which corresponds to a 10 dB increase. So we would perceive the bare barrel (98.83 dB) to be about twice as loud as the Wolf 30mm (88.43).
Again these are just relative comparisons that may prove useful. No science was harmed (or even used) in the testing of these LDCs!
If nothing else, I hope you found this little LDC adventure entertaining.
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Great testing there Charlie. Every gun has different characteristics, but this is a great baseline using a fairly common set-up. Thanks for putting in the time to test/post this.
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Charlie, thanks for testing and sharing, great job.
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Great review with a lot of effort! thank You!!!
KnifeMaker
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Great stuff. Thanks for taking the time to put this out there. 8)
Just to add my 2 cents, I have an assortment Clagues; one for a Boss .22, another for a Bulldog. Internally, they are quite different...and I've noticed it affects sound output.
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Excellent! Thanks for putting this together, Charlie!
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Thanks for sharing its nicer when there is some data to back up ones ear alone.
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No science was harmed (or even used) in the testing of these LDCs!
I beg to differ! Los of science used in this test!!
(I do agree that none was harmed though ;) )
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Thank you for making the significant effort to generate the data AND present it in a logical and easy to understand format.
I've seen some "data" that's impossible to interpret, this is EASY.
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Hey Charlie, Is the only difference between this test and the previous...
https://www.gatewaytoairguns.org/GTA/index.php?topic=178850.0 (https://www.gatewaytoairguns.org/GTA/index.php?topic=178850.0)
Is that this was shooting a pellet, not dry firing?
Just wondering how the DFL Sumo came out above the Tanto this time.
I purchased a Tanto based on your previous test and am VERY happy with it..
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Charlie, Very well done and very useful information.
Thank you for all of the work you put into this and for sharing it with us. 8)
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Good information.
Good to know the results using pellets.
I like the way you sorted the information different ways.
It is interesting to compare the sound with pellets vs the sound without pellets from before.
Thank you Charlie.
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Charlie great write up thank you.
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Thanks gents (no ladies on here so far, right?), it is a good feeling to know that this turned out useful for some.
My only hope is to add more and more units as time and finances permit, as well as testing them through higher (and perhaps even lower?) powered airguns. :D
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So,
what's the real world difference, .......to your ear if you are downrange between 83 and 85 ?
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Hey Charlie, Is the only difference between this test and the previous...
https://www.gatewaytoairguns.org/GTA/index.php?topic=178850.0 (https://www.gatewaytoairguns.org/GTA/index.php?topic=178850.0)
Is that this was shooting a pellet, not dry firing?
Just wondering how the DFL Sumo came out above the Tanto this time.
I purchased a Tanto based on your previous test and am VERY happy with it..
Scott, you are correct. This is the same basic test except With pellets (slaps hand to forehead) ::). I was informed that With a pellet the air behind it is forced deeper and more thoroughly into/around/through all the little air trap crevices engineered to keep more air occupied by swirling around inside rather than exiting the barrel at the same time/velocity as the pellet itself.
To be fair the Tanto and Sumo are both subjectively very quiet to begin with, as were all the units actually, especially when fired right after hearing it with a bare barrel. But the differences present themselves in different ways, especially when talking about perceived volume as well as the more subjective "type" of sound each one makes, as has been described in other threads. At least the Tanto is more compact, but at no time did I feel the Sumo was like a "soup can" or anything overly large.
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Charlie, 😊
you've done good, VERY GOOD! 👍🏼
Thank you for all your efforts to help us select the right silencer. 👍🏼
This is excellent information.
And excellently presented.
Including your explanation of +3dB and the +10dB increases. 👍🏼
I will have this added shortly to the Silencer Specs Table! 😊
Matthias
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So,
what's the real world difference, .......to your ear if you are downrange between 83 and 85 ?
Manny, this trial was like testing a bunch of car tires on one certain car at one certain speed. The higher performance tires would likely perform and hold up better if run on a Porsche or Ferrari.
In other words, the Clague unit (which was built for 50fpe according to Neil) has a significant initial expansion chamber in the first couple of inches (based on what I could see internally with a magnifier from one end and a light shining through the other, it was impossible to disassemble without ruining it) and I suspect if this test was done with a 50fpe gun the Clague would have reduced more perceived output than most of the others which were not designed specifically for higher-powered airguns. In fact such a powerful gun would likely have damaged some of the lighter weight units.
I am starting to think of shooting these through a low power gun, CO2 perhaps, just to see what kind of readings I get. But on such a gun I don't think the significantly larger units would do much more to reduce sound output than the smaller units.
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Charlie, 😊
you've done good, VERY GOOD! 👍🏼
Thank you for all your efforts to help us select the right silencer. 👍🏼
This is excellent information.
And excellently presented.
Including your explanation of +3dB and the +10dB increases. 👍🏼
I will have this added shortly to the Silencer Specs Table! 😊
Matthias
Thanks Matthias, I also have the length/diameter measurements of each one which I used to calculate their cubic inch volumes, LMK if needed and I'll PM/e-mail them to you.
The dB explanation was a conclusion I drew from studying a bunch of online articles which I thought were helpful, so I threw it in.
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JungleShooter, is your Silencer Spec Table for public consumption? I'd love to take a look at it if it is.
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7 of the 10 tested without pellets were more quiet WITH pellets.
It would be interesting to see the results from lower powered air guns and also pistols like a PP700 or PP750.
My Maximus shoots JSB 8.44 at 890 fps = 14.8 ft lbs and is LOUD without Geo's LDC.
This is VERY good information:
"Also the sound deadening effect is notably dramatic going from bare barrel to any LDC. Even the loudest unit, the Polish Wolf 30mm, was noticeably quieter than the bare barrel. It should be remembered that on the decibel scale, doubling the intensity corresponds to an increase of 3 dB. This does not correspond to a perceived doubling of loudness, however. We perceive loudness to be doubled when the intensity increases by a factor of 10, which corresponds to a 10 dB increase. So we would perceive the bare barrel (98.83 dB) to be about twice as loud as the Wolf 30mm (88.43)."
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Great test!
Another at low volume/low velocity would be an interesting comparison.
I find that small reductions in speed can often reveal a threshold point where the sound is significantly reduced.
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7 of the 10 tested without pellets were more quiet WITH pellets.
It would be interesting to see the results from lower powered air guns and also pistols like a PP700 or PP750.
So noted Earl. I don’t have that PP750 pistol any longer but for lower power maybe a Diana Chaser (CO2) might fit the bill.
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Great test!
Another at low volume/low velocity would be an interesting comparison.
I find that small reductions in speed can often reveal a threshold point where the sound is significantly reduced.
Interesting point Thane, a velocity “trip point” threshold...it would be useful to see if the big boy units are effectively quieter than the little guys when tested at slower speeds because if not, that might tell us something even more useful...like using specific units for specific power applications.
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7 of the 10 tested without pellets were more quiet WITH pellets.
It would be interesting to see the results from lower powered air guns and also pistols like a PP700 or PP750.
So noted Earl. I don’t have that PP750 pistol any longer but for lower power maybe a Diana Chaser (CO2) might fit the bill.
Yes, the Diana Chaser CO2 with the 8 inch barrel would be a great test.
My Mrodair CP-2 CO2(same as the Diana Chaser) with the 8 inch barrel and LDC is very quiet but it is pretty loud inside without the LDC.
It shoots JSB 8.44 at 486 fps = 4.4 ft lbs.
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🔴 Silencer Specs Table 🔴
▪50 Silencers▪10 Silencer tests▪6 calibers▪Diameter from .88" to 2.0"▪Length from 2.9" to 10.5"▪Prices from $26 to $270
▪Links
Happy silencer shopping everyone. 😄
Matthias
❌ Attachment Silencer Specs Table Version 20:
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Thank you for this, an excellent way for an inexperienced new buyer to really get an idea of what they're looking at/for.
Will be bookmarking for future reference,
Jesse
PS-And thank you JungleShooter for compiling existing data and maintaining a table of it, efforts like this are what sets the GTA forum up a notch!
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Thank you for your efforts!
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7 of the 10 tested without pellets were more quiet WITH pellets.
It would be interesting to see the results from lower powered air guns and also pistols like a PP700 or PP750.
So noted Earl. I don’t have that PP750 pistol any longer but for lower power maybe a Diana Chaser (CO2) might fit the bill.
Yes, the Diana Chaser CO2 with the 8 inch barrel would be a great test.
My Mrodair CP-2 CO2(same as the Diana Chaser) with the 8 inch barrel and LDC is very quiet but it is pretty loud inside without the LDC.
It shoots JSB 8.44 at 486 fps = 4.4 ft lbs.
Oh, with the pistol barrel? Yeah, my .22 sure is loud as heck with the short barrel! I was thinking with the 19" rifle barrel...but the pistol barrel might be a better test since most of the gases would still be traveling quite fast within the 8"...
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Did you notice a significantly different tone coming from the standard Falx as I did with the high flow version? Just as a lower powered test would be interesting, I think a higher powered test would be as well!
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Did you notice a significantly different tone coming from the standard Falx as I did with the high flow version? Just as a lower powered test would be interesting, I think a higher powered test would be as well!
Good question Donny but to tell the truth, I did not really notice only because I was all caught up in making sure the sound meter was set to freeze the highest dB reading on each shot among other stuff. Plus I was outside with many ambient sounds, as well as the neighbor's A/C cycling on and off right on other side of wall, plus jet planes passing overhead so I had to wait for things to pass by and/or cycle off for every shot. It was tedious (although enjoyable) and I'm not so sharp no more...but I'll try to get an isolated comparo a bit later, see if I can differentiate high pitch vs low, etc. No guarantees though, I've had a lifetime of employment-required quarterly firearms qualifications and the like, and back in the really "olden days" when i was a rookie we felt only sissies wore ear protection while shooting (which I truly regret now)... ::)
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Gotcha 8)
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Gotcha 8)
In fact for "type of sound" tests I may need to enlist my wife and daughter to be my auditory guinea pigs again...
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Yep, very important to have someone down range to actually tells you what they sound from the other side.
Looong time ago I used to have a Marauder .25 and an early days Rainstorm .22,
To me the Rainstorm sounded louder, but one day I had a friend over shooting and first I had him stay downrange and then I did while he was shooting them, we both agreed that the Marauder was actually louder or it sounded louder.
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Thank you for making the significant effort to generate the data AND present it in a logical and easy to understand format.
I've seen some "data" that's impossible to interpret, this is EASY.
Let me second that emotion! Easy-to-understand format. Yes. Very clear.
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Thank you for making the significant effort to generate the data AND present it in a logical and easy to understand format.
I've seen some "data" that's impossible to interpret, this is EASY.
Let me second that emotion! Easy-to-understand format. Yes. Very clear.
Thanks Robert! Simple is as simple does, and I am for exactly that - simple. ;D
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Yep, very important to have someone down range to actually tells you what they sound from the other side.
Looong time ago I used to have a Marauder .25 and an early days Rainstorm .22,
To me the Rainstorm sounded louder, but one day I had a friend over shooting and first I had him stay downrange and then I did while he was shooting them, we both agreed that the Marauder was actually louder or it sounded louder.
Good point Manny, in fact I had to avoid using the Evanix AR6K despite it having the "loudest bark" subjectively. Mainly because of the slight air leakage from between the mating surfaces of the pellet cylinder and the breech block. Regardless of the silencer used up front, the secondary air leakage right near the shooter's face always makes the gun seem loud to the shooter. Downrange ears would help eliminate that.
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Below are some decibel readings using my iphone 7 with the Decibel X app. and averaging 5 shots inside my den.
Benjamin Marauder shooting JSB 10.34 grain at 782 fps, 76.6 decibels at 6 feet left of the muzzle, 91.4 decibels at the shooter's ear.
Crosman Challenger shooting JSB 8.44 grain at 603 fps, 86.7 decibels at 6 feet left of the muzzle, 90.5 decibels at the shooter's ear.
Beeman P17 shooting RWS R10 7.0 grain at 398 fps, 88.8 decibels at 6 feet left of the muzzle, 100.9 decibels at the shooter's ear.
The Marauder sounds like a dull thud at the shooter's ear.
The P17 is a sharp crack at the shooter's ear.
The Decibel X app. gave consistent readings. Example: 76.6, 76.9, 77.1, 75.8, 77.0
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Below are some decibel readings using my iphone 7 with the Decibel X app. and averaging 5 shots inside my den.
Benjamin Marauder shooting JSB 10.34 grain at 782 fps, 76.6 decibels at 6 feet left of the muzzle, 91.4 decibels at the shooter's ear.
Crosman Challenger shooting JSB 8.44 grain at 603 fps, 86.7 decibels at 6 feet left of the muzzle, 90.5 decibels at the shooter's ear.
Beeman P17 shooting RWS R10 7.0 grain at 398 fps, 88.8 decibels at 6 feet left of the muzzle, 100.9 decibels at the shooter's ear.
The Marauder sounds like a dull thud at the shooter's ear.
The P17 is a sharp crack at the shooter's ear.
The Decibel X app. gave consistent readings. Example: 76.6, 76.9, 77.1, 75.8, 77.0
Earl, thanks for your helpful input! Are any (or every) of the guns moderated at all? I know the mrod has baffles in the shroud, correct?
Also curious how you were able to get the slightly different dB readings between the muzzle and the ear. That would be a definite improvement on testing protocols, did you need to use two phones?
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Took Maxine out with the Tanto and my cell phone playing music was much louder.
For you poor folks living in an urban setting I suggest playing something neutral and soothing like this in the background... cranked to 11 to mask the report.
Trust me... they won't mind the airgun. ;)
https://www.youtube.com/watch?v=a64cJiGKr7c (https://www.youtube.com/watch?v=a64cJiGKr7c)
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I suggest playing something neutral and soothing like this in the background... cranked to 11 to mask the report.
Trust me... they won't mind the airgun. ;)
I like drum solos for that. Who is going to notice a few added pops and clicks? :)
https://youtu.be/FqJdzYY_Fas
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;D
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Below are some decibel readings using my iphone 7 with the Decibel X app. and averaging 5 shots inside my den.
Benjamin Marauder shooting JSB 10.34 grain at 782 fps, 76.6 decibels at 6 feet left of the muzzle, 91.4 decibels at the shooter's ear.
Crosman Challenger shooting JSB 8.44 grain at 603 fps, 86.7 decibels at 6 feet left of the muzzle, 90.5 decibels at the shooter's ear.
Beeman P17 shooting RWS R10 7.0 grain at 398 fps, 88.8 decibels at 6 feet left of the muzzle, 100.9 decibels at the shooter's ear.
The Marauder sounds like a dull thud at the shooter's ear.
The P17 is a sharp crack at the shooter's ear.
The Decibel X app. gave consistent readings. Example: 76.6, 76.9, 77.1, 75.8, 77.0
Earl, thanks for your helpful input! Are any (or every) of the guns moderated at all? I know the mrod has baffles in the shroud, correct?
Also curious how you were able to get the slightly different dB readings between the muzzle and the ear. That would be a definite improvement on testing protocols, did you need to use two phones?
The guns were not moderated. The mrod has the stock baffles in the shroud.
I put the iphone 6 feet left of the muzzle like you did.
Then I shot 5 shots and averaged them.
Then I put the iphone even with the shooter's ear and shot 5 shots and averaged them.
I used the same iphone for all measurements.
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Took Maxine out with the Tanto and my cell phone playing music was much louder.
For you poor folks living in an urban setting I suggest playing something neutral and soothing like this in the background... cranked to 11 to mask the report.
Trust me... they won't mind the airgun. ;)
https://www.youtube.com/watch?v=a64cJiGKr7c (https://www.youtube.com/watch?v=a64cJiGKr7c)
Capital idea, Scott. I also sometimes wait for the neighbor's gardener to show up with his gas weedwacker and leaf blower.
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Below are some decibel readings using my iphone 7 with the Decibel X app. and averaging 5 shots inside my den.
Benjamin Marauder shooting JSB 10.34 grain at 782 fps, 76.6 decibels at 6 feet left of the muzzle, 91.4 decibels at the shooter's ear.
Crosman Challenger shooting JSB 8.44 grain at 603 fps, 86.7 decibels at 6 feet left of the muzzle, 90.5 decibels at the shooter's ear.
Beeman P17 shooting RWS R10 7.0 grain at 398 fps, 88.8 decibels at 6 feet left of the muzzle, 100.9 decibels at the shooter's ear.
The Marauder sounds like a dull thud at the shooter's ear.
The P17 is a sharp crack at the shooter's ear.
The Decibel X app. gave consistent readings. Example: 76.6, 76.9, 77.1, 75.8, 77.0
Earl, thanks for your helpful input! Are any (or every) of the guns moderated at all? I know the mrod has baffles in the shroud, correct?
Also curious how you were able to get the slightly different dB readings between the muzzle and the ear. That would be a definite improvement on testing protocols, did you need to use two phones?
The guns were not moderated. The mrod has the stock baffles in the shroud.
I put the iphone 6 feet left of the muzzle like you did.
Then I shot 5 shots and averaged them.
Then I put the iphone even with the shooter's ear and shot 5 shots and averaged them.
I used the same iphone for all measurements.
Thanks. Very interesting that the gun metered louder when closer toward the back (behind the muzzle). I wonder if the noise of the action contributed to the max reading. I always figured the closer to the muzzle blast the louder the report would register. interesting twist to this, especially the P17.
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"Breech loud" pneumatics may have a leaky breech O-ring. Lay a strip of toilet paper over the breech and see if that moves when you shoot. A bad leak will rip the paper. It can also sound like it wants to rip your ear drums...
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Radiated sound intensity drops off with the square of the distance from the source (just like light from a bulb). Higher frequency sound waves are absorbed more by objects (even air molecules, over distance) than low frequencies (hence mostly the thump-thump of distant party music can be heard). So, it is entirely possible for a professional peak sound meter to measure one gun or configuration as louder near the muzzle than another; then for the quieter one to sound louder 25 yards away. It has to do with the mix of frequencies in the report.
It is not just loudness of audible sound that matters, but its propensity to grab attention - to make your perk up and actively listen; especially if the sound is repeated at short intervals. Some sounds "stick out" above ambient sounds more than others. I think that prey animals are instinctively programed to pay attention to the sound of snapping twigs. That sounds signals a large animal moving closer - something that needs immediate attention, in case it is a predator.
Predators (including humans) are also attuned to snapping noises, because it signals a large potential meal. So, a sharp snap is much more attentions grabbing for its measurable loudness than a longer "shoo", that starts (and ends) with a ramp, rather than silent to full intensity in an instant.
Repetitive sounds also grab attention out of proportion to their actual loudness. Hence, we may miss a single knock on the door, but not four knocks, repeated in quick succession. With airguns; the report, followed by the sound of the pellet smacking the target can be such an attention grabbing signal. As can just the fact that the same unnatural double-sound repeats every so many seconds.
Better for your airgun to sound like a sneeze with an echo, than someone sneaking around in the backyard, stepping on twigs.
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Subscriber,
Thank you for this much needed
🔶 psychology of gun shot silencing! 🔶
We can measure all we want, but the dB numbers are only one dimension, and hiding sound from quarry or quarrelers (i.e., neighbors) has more than one dimension!
I'll probably end up writing a short guide to silencers, and I'd like to quote you, if I may!
Matthias
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Go ahead, Matthias,
I am glad what I suggested makes enough sense to include in your guide.
If I were to write an airgun moderator guide, I would include an introduction; possibly including some of the thoughts I brain dumped below (feel free to include as much or as little of the text below as you like):
The standard microphone placement for measuring muzzle report intensity was first determined with and for firearms. While that is still useful for airguns, the mission and purpose of suppression are different, with some overlap:
The obvious purpose of sound suppression with firearms is hearing preservation for the person shooting the gun. Hence the multitude of devices that still allow sound levels of 130 dB - just considered "hearing safe". Now, one would think that the microphone standard placement should then be located nearer the shooter's ear (and it is catching on as a second data point). The problem with that, from a suppressor manufacturer's perspective is that they have no control over barrel length and action type. This matters because not only are shorter barrel rifles much louder, the suppressor muzzle being even 6" closer to the shooters ear will have the mic capture much higher sound pressure (some examples of dB to distance are given below). Also; self loading firearms have more "pop" at the breech than manually operated ones. Higher dB scores without cross platform understanding can cost sales. Hence mic placement relative to the muzzle as industry standard.
Depending on the exact mission, suppressing of the sound source location and direction from the target's perspective might be more important than a firearm being rendered hearing safe. A consideration important to hunters is the avoidance of spooking other game animals. At the bottom of the list, is making ranges quieter for competitors and neighboring properties.
Large bore high power airguns share many of the above goals because, unshrouded, they are very loud. Low power, small caliber and shrouded airguns are mostly hearing safe to the shooter, out of the box. Adding a LDC to them, is done to mute their sound signature further, so as not to annoy family members or neighbors. And, generally not to draw attention.
As such, microphone (objective) and ear (subjective) placement when comparing LDCs on low power, small caliber shrouded airguns needs to have their usefulness ranking weighted more heavily towards measurements obtained at 10, 20, 30+ yards from the muzzle. Both off to the side; and almost directly in front of the muzzle (with safe backstop considerations in place). This is in addition to the standard mic placement near the muzzle. The point is to recognize that because LDC goals may be different, appropriate measurement methods and standards can and should be different.
I think that any system of airgun report measurement can be very useful, providing it can be explained and repeated. I see airguns test videos by "reputable evaluators" where the microphone sometimes seems 3 feet from the muzzle, and sometimes closer to 4 feet. Often placed on a hard table where there is no regard for the effect of reflected sound. Meanwhile, the actual difference in sound pressure at 3 and 4 feet from the muzzle would actually measure 78% higher at 3 feet than 4, for the same shot. So, if you are going to measure sound at 20 yards, and have a one foot variation in mic placement, the error would be only 5%.
Now, all I need is a good editor....
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Subscriber, thanks for your great explanation as it cleared up a lot of questions that I had.
I all makes a lot more sense.
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Took Maxine out with the Tanto and my cell phone playing music was much louder.
For you poor folks living in an urban setting I suggest playing something neutral and soothing like this in the background... cranked to 11 to mask the report.
Trust me... they won't mind the airgun. ;)
https://www.youtube.com/watch?v=a64cJiGKr7c (https://www.youtube.com/watch?v=a64cJiGKr7c)
Isn't that the track they used in one of the Star Trek movies? I can see Kirk in his chair smiling as I start listening to it. "Is that classical music?" asks Bones (I think)?
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Below are some decibel readings using my iphone 7 with the Decibel X app. and averaging 5 shots inside my den.
Benjamin Marauder shooting JSB 10.34 grain at 782 fps, 76.6 decibels at 6 feet left of the muzzle, 91.4 decibels at the shooter's ear.
Crosman Challenger shooting JSB 8.44 grain at 603 fps, 86.7 decibels at 6 feet left of the muzzle, 90.5 decibels at the shooter's ear.
Beeman P17 shooting RWS R10 7.0 grain at 398 fps, 88.8 decibels at 6 feet left of the muzzle, 100.9 decibels at the shooter's ear.
The Marauder sounds like a dull thud at the shooter's ear.
The P17 is a sharp crack at the shooter's ear.
The Decibel X app. gave consistent readings. Example: 76.6, 76.9, 77.1, 75.8, 77.0
Earl, thanks for your helpful input! Are any (or every) of the guns moderated at all? I know the mrod has baffles in the shroud, correct?
Also curious how you were able to get the slightly different dB readings between the muzzle and the ear. That would be a definite improvement on testing protocols, did you need to use two phones?
The guns were not moderated. The mrod has the stock baffles in the shroud.
I put the iphone 6 feet left of the muzzle like you did.
Then I shot 5 shots and averaged them.
Then I put the iphone even with the shooter's ear and shot 5 shots and averaged them.
I used the same iphone for all measurements.
Thanks. Very interesting that the gun metered louder when closer toward the back (behind the muzzle). I wonder if the noise of the action contributed to the max reading. I always figured the closer to the muzzle blast the louder the report would register. interesting twist to this, especially the P17.
Please note:
The low readings are 6 feet from the muzzle to the side.
The shooter's ear was 3 feet from the muzzle to the rear on the rifles and 2 feet for the pistol.
Closer to the muzzle gives more decibels.
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Peter / subscriber,
your profound understanding of they physics of much of airgunning is a huge benefit to our AG community.
Thanks for sharing it!
❌ If there is enough interest — couldn't we establish a silencer test standard?
❌ And couldn't we publish the results for all to see — webpages are cheap?
🔸We already have the general idea of where to place the sound meter — adapted to the purpose of an AG silencer. ✔️
🔸We already have a specs table of most commercial silencers. ✔️
🔸We already have a bunch of people interested in this. ✔️
🔸We already have the precedent of an airgunner (STO) receiving test samples on loan from fellow airgunners. We could do the same. ✔️
🔸I'm outside the US, so I can't do the testing.
But I can offer $50 toward a higher quality sound measuring device.
And I can offer to do some of the writing. Peter, you do good writing yourself!
And we could even publish the results in a scientific journal, or an airgun magazine, if we're so inclined.
🔶 We can ask the manufacturers for sponsorship — no strings attached.
However, I doubt if they are going to establish the test standards....
So, if we, the users, aren't going to do it, who will?!
Who joins up?! 😄
Matthias
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Walmart has a decibel meter on sale for $18.03 (List $54.09).
https://www.walmart.com/ip/BENETECH-Noise-Meter-Sound-Decibel-Meter-Digital-Mini-Pressure-Level-Meter-Audio-Measurement-30-130dBA-MAX-MIN-Hold-Auto-Backlight-Batteries-included/719174741 (https://www.walmart.com/ip/BENETECH-Noise-Meter-Sound-Decibel-Meter-Digital-Mini-Pressure-Level-Meter-Audio-Measurement-30-130dBA-MAX-MIN-Hold-Auto-Backlight-Batteries-included/719174741)
I am happy with the free iphone app "Decibel X".
The "Decibel X" app seems to give consistent readings and is free and easy to use.
https://apps.apple.com/us/app/decibel-x-db-sound-level-meter/id448155923 (https://apps.apple.com/us/app/decibel-x-db-sound-level-meter/id448155923)
Someone please compare the Digital X app to their sound meter and tell us if the readings are the same.
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One thing that using a cellphone mic is that it may have some built in sound reduction built in.
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One thing that using a cellphone mic is that it may have some built in sound reduction built in.
When I did some testing of my PCP with and without its shroud and another LDC I had on hand, the limits of the microphone soon came up in two areas:
- Frequency response:
The microphone I was using, a USB AT2020, has a pretty solid cut-off at 20kHz. That was likely a physical limit (the analog versions of this mic have the same limit), but the internal electronics had a limit not very far above that. It's a nice microphone, but when I looked at the data, it made me wonder: is there more to see or hear (if my ears were that good)? More to the point, is my shroud or this LDC shrieking at frequencies I can't hear but that my game or the neighbor's dogs might be able to hear? Perhaps of no consequence, but now I wanted to know. - Accuracy:
Most microphones don't have a constant sensitivity across the entire frequency range of the measurement. The At2020 differs by only 3 dB from 200 Hz to 10kHz. It's a small difference, but not every mic you pick up is so nicely behaved, and that can affect how well you compare measurements done with other microphones. The mics in phones are specially designed for a pleasant voice measurement--and who knows what the electronics do to it after that.
Research on the problem lead to "measurement microphones"--microphones with very flat frequency response characteristics across the whole input range. Some of these microphones are "flat" clear out to 50kHz. We can't hear that, but the audiophiles swear they can hear the difference in stuff recorded by a 40kHz capable Earthworks SR40V and "lesser" 20kHz capable microphones. Apparently, in addition to high frequency response, in the better mic there is an more accurate representation of the sound being measured due to the lack of subtle phase shifts or time delays at different frequencies across the spectrum.
Anyway, that has put me on another project: acquire an SR40V and a high quality USB recording interface (i.e. high sample rate) and repeat my test to see what I see in the data. The SR40V is not as specialized as a mic like the Earthworks M50 (50kHz capable), but it is almost as good out to 40kHz and a really good mic to have if a person thought they wanted to own a good mic. The interface can sample at 192kHz, easily digitizing whatever the microphone is "hearing". The goodies arrive this week and I hope to repeat the measurements and post a separate thread about it. (Yes, yes, I could have purchased a lot of air rifle toys for the money, but it actually wasn't my money. I did some work for a friend and he was willing to do the shopping for me...)
Yeah, absolutely accurate measurements that can be shared between folks for comparison with other measurements is not easily done. And sound is that much harder because so much depends on the equipment too. You can calibrate a scale or caliper with a calibration weight or gage block and you're good. But calibrating a microphone...yikes. Back-to-back measurements like those presented here are about the best you can do, and even then you have to make sure you set everything up the same each time.
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Matthias,
I appreciate your abundant energy and "unbridled enthusiasm". I still have the latter, but my energy went walkabout...
I agree to the extent that I am willing to gift this sound meter to the effort:
www.amazon.com/gp/product/B000EWY67W/ (http://www.amazon.com/gp/product/B000EWY67W/)]www.amazon.com/gp/product/B000EWY67W
It is the one that appears in the Pyramyd Air test videos. That is why I bought it. Not junk, and not super expensive.
As we are raining on Charlie's parade here, I think he should be the recipient of the sound meter (if he wants it). He is also a long way towards testing LDCs, in a way that makes sense to him (and by background conversation, makes sense to me).
I am full of ideas and opinions; and can express them reasonably clearly. That does not make me "right" about this topic. I think that the people doing the actual testing should be free to develop airgun LDC test methods that suit them.
Only after they are happy with their results would we consider such a method for standardization. Such standards should be accepted because they make sense - if they make sense. Sure, I could write a test procedure, but it would need to be considered a place holder. A starting point. Not "law". I think my philosophical posts above actually go far enough (and too far, considering the reason why this thread was started).
I happen to know that Charlie is benchmarking LDCs for his own purposes - for him to share or not. The fact that he has been gracious enough to share his results might not indicate that he thinks his evaluation methods are inadequate, or need to be standardized.
I think that a separate thread could be started about standardizing airgun LDC test standards. Travis, the GTA forum Administrator started such a thread a few months ago. Why not coordinate with him?
As for publishing anything related to "LDCs" in a scientific journal; I disagree on two counts:
1. Airgun LDCs fly under the radar. The more we publish about them outside the airgun community, the more likely they are to get unwanted attention.
2. Exactly what defines the gold standard "mouse fart quiet" LDC, is highly subjective. Meticulous calibrated instrumented measurements are unlikely to settle any disputes. We may (will) find some LDCs measure "louder", but sound quieter than others. Other than that paradox being interesting to PhD types, it does not help one make a better purchase decision.
I think that consolidating the results and methods used by people who publish clear tables of useful information, such as yourself is a great idea. That could be a section on this forum. It could have limited access. For instance, on some forums, non-members cannot see imbedded images. They have to join and log in first. On others forums, sections may politely inform a viewer of their lack of credentials to access that part of the forum. If a standard test method should develop amongst the people that do all the work and incur all the expense, then that would be good and right. I might have an opinion about their test methods, but that is all it is. They don't have to follow it.
I will close by expressing this opinion: If a person can spend over $1000 on a dozen LDCs for comparative testing, then the same person can spend $100 on a reasonably accurate and appropriate dB meter. Using cell phone apps would be cheaping out, and the results would be much less meaningful than comparative ear measurements. It would be a bit like a guy spending $200k on a new Ferrari, then running low octane gas in it to save money...
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Hey Sub, ask me no questions and I'll tell you no lies... ;D ;D ;D