I metered the Thompson machine sg-2 on the scorpion evo 3. Did 5 shot groups with fiocchi 158gr
1 meter left of muzzle:
1) 132.7
2) 129.8
3) 126.3
4) 127.8
5) 125.3
5 shot avg. 128.38

At shooters left ear:
1) 130.9
2) 129.2
3) 130.2
4) 131.8
5) 129.1
5 shot avg. 130.24

At shooters right ear:
1) 139.1
2) 139.9
3) 138.7
4) 139.5
5) 139
5 shot avg. 139.24

I guess I need to check other Db readings to see how this compares. I have a SG-2 pending and it will live on a Scorpion until I buy an MP5

Any other cans you can meter to compare with the fiocchi?
Also, I'm sure it's a long shot but do you have a tirant 9mm and American Eagle 147s? Lol

Deleted.

Right now all I can do for comparison is with the sico hybrid, I have a rugged obsidian coming in a few weeks, sorry no tirant.

Haha no pr Blem. Thanks again for doing this

That sure seems to be a super loud suppressor on a nearly 8" barrel with a 9+ inch subgun silencer that is 1.625"OD.  Assuming you are using the correct equipment (not a digital meter from Larson Davis or a digital B&K 2270) the host is not a good silencer host or the suppressor is loud or both.  The suppressor has over 50% more volume than a 1.375OD suppressor that is 8.5" long.  Monocore silencers are always louder for the same size unit, but this seems extreme.  The shooters right ear numbers you post are not hearing safe by european standards and borderline not hearing safe with US standards.  Did you take unsuppressed readings at all three locations?  When you metered at the "muzzle" did you meter at the end of the host weapon barrel or the end of the silencer?

I did the readings with the Larson Davis lxt1-qpr it is digital, but if you know who Dr. Dater is he has an article on this meter and also a few posts that he has compared it against the gold standard Larson Davis 800 and with c weighting (this is what I used) it is nearly identical in numbers only +- 1db. I did my testing 1 meter left at the end of the suppressor, I'm not looking to try and find the optimal position to get the lowest numbers but want to give real world numbers without all the other setups the company's use for marketing. I think these numbers are not bad on this host, your not going to see real numbers much lower at the muzzle on a 9mm. I will get you base line no suppressor numbers later today.


This is copied from Dr Phil Daters post on this forum about the Larson Davis:

The Larson Davis LxT1 (or its slightly more tricked up version, 831) with a rise time of 28 microseconds is the next best thing to an 800B or a 2209. It is reasonably economical (in the $2500 range plus calibrator) and is far better than almost any other portable meter on the market for firearms. Our experience has been that with C-weighting, it reads within 1 dB of the 800B. Unweighted, it reads about 4-5 dB low. The LxT1 is also current production, while the 800B and 2209 are long discontinued and repairs are becoming problematic as the manufacturers run out of spare parts.

C weighting is not the standard.  Using digital sound meters that are this slow don't comply with the standard.  Phil knows this.  These numbers are actually really bad for a near 8" barrel and considering you are using a slow meter, they are likely much worse that what you got.  Real numbers that are much lower have easily been achieved with other suppressors with half the volume...like 122 ish...using proper equipment..and the standard testing methods.

The LD 800B is not the gold standard, its one of two analog meters that comply with the standards (they are older and harder to find parts for).  B&K have two offerings that are portable that meet the current standards.  They are not cheap like $2500 cheap, but one is less than 16K.  Using slow meters and non-standard testing is no substitute for correct equipment and methodology.   I am surprised that PHD would accept results from a meter that he knows cannot show the peak reading of a suppressed gunshot.

Well unless you have some credintials to dispute what PHD says you seem to just be a person who doesn't want people to see real numbers. Name 1 9mm suppressor that hits 122 and I'll test it.

I'd take 1928A1's knowledge and experience with regard to meter testing.

I also wrote up some stuff regarding undersampling with digital meters and how it could easily miss the peak of a transient noise source - although it's probably in the archives by now.

FWIW, MIL-STD Rev E made the sampling requirements even more stringent than the Rev D that people oft refer to.

So if this meter is tested side by side with the 800B or 2209 and they are within +- 1 db is that not good enough?

So is my SG-2 going to be quiet or not?

Yep

Maybe today it's not really substandard. What it comes down to is if it meters the same as the analog +- 1db with c weighting why would anyone care? You can't buy the analog meters anymore and this one has been said to be the best going at this time and if comparisons are made with same meter and all other things equal it should show the difference between them. I would love to put this side by side with what everyone thinks is the standard and see what it shows. My guess is if they are extremely close some will come up with other reasons to cut them down. All I want to do is compare different cans and see what designs work more efficiently than others.

Without going into an obscene amount of detail let me explain.  Silencers must be tested to some standard.  This standard has traditionally been the military standard.  Alan C Paulson used it, Philip H Dater used it, C Reed Knight used it...and anyone else that tests silencers in any official capacity uses some sort of standard.  That standard is MIL SPEC 1474 C D and now E.  Most of what you can find out there regarding correct independent testing was done to MIL SPEC 1474D (and perhaps some C).  There are obvious reasons for using some sort of standard for testing.  Surely you understand that.

The weighting network used in MIL SPEC 1474D was "A" weighting.  I don't care to debate for this discussion if this was the best choice, but it was "A" weighting that was used.  Remember any comparative data that is out there for the last 20 years used this weighting network.  We could get into testing location standards and all that jazz, but for this discussion, the reference location (1 meter from the sound source 1.6 meters above the ground) has been the standard.

The sound meters used had to meet certain standards in testing.  They had to be "fast enough" to catch the peak of the suppressed gunshot.  Proper calibrated equipment must be used to comply with the standard.  

So...without getting into any super deep discussion regarding testing standards, I hope this will be enough to clear it up a bit.  

Now, your meter.  Your meter does NOT MEET THE TESTING STANDARDS.  It didn't meet the testing standards established in February of 1997 (almost 20 years ago).  It doesn't meet the standard of the E Revision. Your sound meter is only capable of 51,200 samples per second.  Mil Standard 1474D required a minimum of 160,000 and the new standard requires a minimum of 192,000 samples per second.  So regardless of which weighting network you use, your meter simply isn't going to be acceptable for silencer testing.  Mil Standard 1474E also specifically calls for peak impulse SPL readings to be unweighted (which PHD says are 4-5dB LOW using this meter).  Impulse SPL reading are used for gunshot noise testing.  

All that being said...this silencer you tested is loud.  Even using incorrect equipment, no standard and off the cuff testing its loud.  Find an AAC TiRant 9MM and test again.  Do 5 shots unsuppressed at all locations.  Do ten shots suppressed at all locations.  Post A weighting, C weighting and no weighting results.  Post your ammo type, temperature, elevation and humidity for the test.  Calibrate your meter before and after the test and note shift, if any.  

https://www.ar15.com/forums/t_6_20/458278_Griffin_Optimus_Sound_tested___Silencer_Shop.html&page=2

Is this what you were referencing?

All that thread tells me is that one of the newer suppressor company's is more than willing to accept the numbers from those meters. I believe that sometimes science makes no difference and if a meter registers +-1db to the mil standard meter then it's good in my book as long as people know that's what you used. If I use this meter on different suppressors and its setup the same for all testing and everything else is the same the comparisons are good. All this other stuff means nothing to the average guy and he wants to see how they all perform before he buys. Some suppressor company's are comfortable with their products being tested with these meters so why would the couple of people responding care? The consumer is getting the information he wants and maybe the consumer suppressor industry should come up with their own standard and if they need to sell to the military they can use their standard.

It should matter because the equipment being used is incapable of accurately sampling the impulse noise from a gunshot. There are papers outside of MIL STD that also corroborate the minimum sampling rate necessary.

If you tools don't work properly than the rest of the data, analysis and conclusions are suspect.

And then we can get into a discussion about how dB doesn't really tell the whole story about how we perceive the performance of a suppressor since it doesn't provide any frequency/amplitude information.

You must have a dog in the fight somewhere so why not say who you work for or company you own? I would love to put my meter against whatever you have or think is acceptable and see the difference so we can report the difference and take that into account. I still think if all things are equal and I test 2 suppressors side by side the results are good but that is the common sense approach not the scientific I have x degree.

I believe Engineer works in 'sound' in an non firearms related industry. He's obviously on top of stuff like this.

Nope, no dog in this fight. My profession is about as far from the firearms industry as you can get.  I have an RF & electrical engineering background and much of my work involves the use of test equipment. Before I am permitted to use any piece of test equipment, I have to write a formal document to verify that the machine's performance is sufficient for what I am measuring or analyzing.

So that's pretty much it - I'm just advocating the use of proper equipment. If your measurement equipment can't provide accurate data then how can you draw meaningful conclusions from it?

This is a good read by Phil Dater whom I trust to be an expert.

http://www.larsondavis.com/ContentStore/mktg/LD_Docs/Firearm_Sound_Briefing.pdf

 
Yes, I've read the presentation


Here's a better article about the effects of sampling rate and the errors produced by undersampling. http://www.canadianaudiologist.ca/impulse-noise-produced-by-weapons-implications-for-hearing-conservation/

The 1meter left readings show a significant amount of 1st round pop, not shown in the other tests, I am going to guess you did not use three meters at same time, but did the tests back to back? Looks like the can was still warm for those 2&3  tests.

Also, the 1meter left readings show the dB dropping to 125. But since you only tested 5 rounds, we do not know if it leveled off around 125 or kept going down. 10 or more shots is needed to know this.

I did use same meter at the different locations did not let it cool completely, I will do more testing next week with more rounds to see where or if it stabilizes.

Thanks, I would really like to know where it bottoms out.

my thoughts

It has some serious first round pop. More testing will tell is if it gets lower than 125. 125 is not too bad for a dry can. But the best cans can get much lower dry. The numbers for shooters ear suck. That suggest the evo is not a great host, as the near 15db difference from reference location is a lot. And as OP states, those ear locations were done with a warm can. It might be higher than 15dB.

What I think is bad is it is a very large can, so it is not very efficient for its size. It is a monocore, I bet if one were to rebaffle with K baffles, it will be mouse farts.

Can I send you my SG-2 next year to test?
ETA: or recore it? Lol

NFAtalk.org metered this can using 2209s compare your results with their info

You're going to make me search, half drunk, huh?

Half drunk here too. Interested to see what you find.

In for the numbers too.

All this thread tells me is there are a bunch of older guys hanging on to old analog equipment that isn't sold anymore, is hard to get parts for, and at some point won't be seen at all anymore.

That means the "standard" is no longer the standard anymore, logically, if the machine that tested the standard is old and who knows how much longer it'll be available.

It's not like everyone is going to hang on to an old, analog standard. Even the military will adjust.

I have no dog, or emotion, in this fight. The logic is the logic.

Plenty of things used to be the standard 25 years ago and now they are not.

Unless you guys expect these analog machines to last forever.

This guy who some of you are suprised would use "substandard" info or machines probably is adjusting for the times and sees the writing on the wall and is smart enough not to hold onto older, soon to be extinct, equipment.

No, it just means that the digital equipment that meets the standards is not cheap, and nobody wants to pay for equipment that actually shows how loud (or quiet) silencers really are these days.  If the consumer is duped into buying loud suppressors with data taken from improper equipment, the only person who pays the price is the consumer.  Silencer companies profit and consumers damage their hearing and that is not fixable.

 
Well, gee, let me whip out the notes I jotted on the back of my AARP card...






It's never been about trying to put analog above digital technology. It's about ensuring that the digital technology used is sufficient for the purposes needed.






MIL-STD-1474D has a section that defines what is the requirement for digital sampling:













a minimum 160 kHz sampling rate.






When the standard was revised to MIl-STD-1474E, the sampling rate requirement for digital sampling of impulse noise was increased:













a minimum of 192 kHz sampling rate.






The standard also defines the signal conditioning that needs to take place before the analog signal is brought into the digital domain and I'm making the assumption that the digital meters apply the same anti-alias filtering to the analog signal before it is digitized.






Anyways, the point is that we aren't trying to hold onto old analog equipment but insist that any digital equipment used meets minimum specifications for what military and industry standards have defined as necessary for properly capturing the impulse noise of a gunshot.









The digital equipment capable of doing this exists, but isn't cheap and may not be as portable as a handheld meter. But that's the cost of obtaining accurate data.







 

Before it gets pushed down in the thread where most people won't read , I hope everyone reads this article by PHD who is as far as I'm concerned the for most expert in the industry. http://www.larsondavis.com/ContentStore/mktg/LD_Docs/Firearm_Sound_Briefing.pdf He gives his years of expertise on these meters and how effective they are. I agree you should always wear hearing protection regardless of what someone says the db level is. There are many factors that can cause 1 persons readings to be different from another's and those same things happen with analog meters. No one can dispute if I do all my testing on the same day using the same methods that my results between 2 different cans aren't a representative of each of their proformance. Tone is subjective and one of those things everyone will hear and look at differently. I'm no engineer nor do I have a fancy degree all I am is an avg. guy whom wants to know which cans preform better than others so I spent a little money to test some things, I guess unless your in the industry or spend 50k for the so called mil standard meters you can't give an opinion or results. This is BS I don't care about military standards as I am not making nor trying to sell suppressors to the military, I want to test what's out there and give some info as to what results are I get, if people want to look at it and take it into consideration before they buy that's up to them. If the meter is good in Phils opinion that's all I need as there is no one in the industry that is more respected.