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I knew this was going to be a trainwreck but didn't think it would happen this quickly.
Interested in an SR5 next to an M42k that should tell us everything we need to know

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Yet, in their PAPER catalog they gave out a SHOT2018, page 30 they list the NUMBERS of the SR-5 as 32dB, 133 dB.

Yeah, "numbers on paper don't mean shit", unless they are posting them. Apparently they were referring to your NUMBERS, when they said "don't mean shit", not theirs. Is that bitch slap they put on your face still red?

again, since you keep ducking the question:

Why did you use a meter, post results, and continue to defend results if "nobody gives a flying fuck about what a meter says"?

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That slide was from tests that I did with the California state crime lab around 9 years ago. I use a Larson Davis 800B with their 1/4" mic (#2530, which is a clone of the B&K 4136). LD claims that the rise time of the LxT1-QPR is 30 microseconds or better, and one of the LD engineers told me that the best a digital peak detector will do is 28 µ-sec. If you will notice on my slide, A-weighting was specified. Weighting networks (A or C) degrade the meter to more closely match the response of the human ear. While I don't know exactly how bad the degradation is, I would guess it is to somewhere close to 25-30 µ-sec. In the video of testing the AAC can, they were using C-weighting, which is fairly similar to A-weighting in performance.

The comparisons I have done on firearm peaks show the LxT1 to read generally less than 2 dB lower than my 800B (which has a measured rise time of 13 µ-sec). However, the real test is unweighted. When unweighted (LD calls it Z-weighting), the LxT1 reads 6-7 dB below the 800B. Regardless, even the 800B (or 2209) misses the peak maximum even unweighted. The B&K Pulse misses less.

2 years ago, a B&K rep passed through Boise to demo to us a Pulse system. We compared it to the 800B, and our finding were that the 800B read only 1-2 dB low when weighted, but unweighted it was closer to 4 dB low. The Pulse theoretically has a rise time in the vicinity of 2 µ-sec, but the 1/4" pressure mic they had possessed a rise time of around 7 µ-sec according to the calibration curves with it. This means simply that the best system rise time could not be any better than the weakest link. My experience has been that some of the 1/4" pressure mics have worse response curves than others. For the Pulse system, one should use a 1/8" pressure mic, and the B&K rep did not show his product in the best possible light.

My experience using the 800B has been that the non-suppressed M4 (14.5" bbl) has a C-weighted SPL of 163-164 dB at the reference location, and a 10" bbl AR runs 167-168 at that location. The 20" barreled M16 runs 162.

Should we be doing SPL measurements unweighted? Of course -- it is the better indication of hearing damage risk. However, use of A- or C-weighting dates back to the mid-to-late 1970s when the 2209 first came out and the early pioneers (Finn, Knight, Walsh) decided the data looked better weighted. This resulted in the new MIL-STD-1472 either specifying or permitting the use of weighting and our industry adopted weighting.

Is the reference location the best place to measure? It is the best estimate of what the target will perceive. The shooter's ear is a better estimate for hearing damage risk, but we negate that benefit by using weighting. And it wasn't until relatively recently that the shooter's ear locations became defined as a specific location in space with reference to the back of the receiver.

Back to the testing video. There are some unanswered questions, and I think the measurements recorded are low. First would be whether the meter had been calibrated with a certified field calibrator (such as the LD CA250, or CA200 as a less accurate second choice). Second was the measurement location (reference, 2 meter spacing instead of 1, ear?). Before I left Gemtech, sound measurements were made on a permanent field jig that positioned the weapon properly and held the microphones on separate permanent locations referencing the muzzle. We also used the 800B. Since I left, I still measure that way and Gemtech is using an LxT1, although they have requested a Pulse from the Mother House.

I hope this helps. I am not an expert, but I have been playing with this stuff for a long time and I have gone through a tedious (and expensive) learning curve on sound measurements. In my opinion, the LxT1-QPR, while not quite as accurate as we would like, is better than most of the alternatives when used with weighting.'

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I think that Dr. Dater is the most knowledgeable and and his years of experience are unmatched here.

He doesn’t discount the lxt1-qpr actually has done direct comparison to his LD 800B and finds it real close as long as it’s calibrated correctly, and the proper weighting is being used.

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Wow, just read this thread and a couple points:

1.  Great seeing all the pros in here providing information.  It's awesome seeing all the guys from different companies providing insight and talking together about a subject.

2.  I don't think I have ever seen one person go down in flames like 10mm lol.  This thread ought to be a lesson on what not to do when information you support is proven wrong by almost every single industry expert in as field.  I kept waiting for him to stop, and he just kept digging in deeper.

I am like a lot of people now, with 10 suppressors I am at the point where I am not chasing a DB claim now, but other points such as customer service, build, mounts, etc.

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I appreciate your videos and the technical interchange you've stimulated.  If I had the time and inclination I could see myself following the approach you did and I hope what you get out of it for yourself continues to be fruitful.  So far based on your comments over on the 54 page GD Trump Battered Wife Syndrome Coming Out Ball I think you've got thick enough skin to take constructive comments to heart and not let the abrasive aspects do any more than help polish your game.

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I've spent a lot of time in the last 10 years metering suppressors and I continue to do so. Both ours and anything else I deem interesting from the other companies. .I've posted more than a few videos online over the years. In the last 2 years I've done side by sides with the LXT at least 6 times. I only have the one on video with Frank from Snipers Hide but the results have always been the same. Others I know in the industry that have done side by sides like Chris have had the same results I have. The LXT is useless and nothing more than a random number generator when it comes to gunshots.I've got together with other suppressor comapnies on several occasions and I've even had other companies that didn't have a meter send me cans to meter for them. I'd like to think I'm trusted for good info. I'm not here to piss in someones Cheerios for the hell of it.I don't know what LXT Dr Phil had or how it was set up but his results are nothing like what I and others in the industry have seen. I will continue to post videos with our trusty old 2209. Like I've said before I shot it side by side with the Pulse system and B&K reps last year. I know the numbers I get are good. I will continue to disregard numbers from machines that do not meet the military equipment specification. I don't think I'm all that smart but when I look at the info about digital meters I understand why they don't work when they fall short of the spec. I don't see how the science is arguable at all especially when my field results match and are exactly the way the science says they should be. When you miss the peak pressure because rise time it to slow and you don't have enough data points because sample rate is also low how can you think you are going to have good numbers?
But what the hell do I know? I'll just keep kicking out cans and videos for you guys to enjoy.

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It metered 158 unsuppressed, - 34 would be 124.  I got as low as 123.7

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I agree that 158 suppressed is low, and 123 is low.  I said that in this thread and I think in the video.  I remember specifically shooting it again because the numbers looked low and I didn't trust them.

The reduction seems about right though.  Which I have said all along too.  Most people in this thread ignore all that and just herp derp ur meter sukz.

If you don't like the videos or find them useful, don't watch them. Many other thousands of people do.

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What you might be not understanding here though is that when a prospective customer watches a review to help them make a purchase, they look to the data in AR15 video as being authoritative. Right or wrong, the videos are taken as fact. The majority of viewers will see “the meter says 124”.

I have zero experience with meters, and frankly don’t want any, but if you choose to use one, it really needs to follow an industry standard. The data is not only skewed, it’s incorrect.

The radar detector analogy someone made previously is a good one to remember: a speed reduction of 85 to 65 is a big difference compared to 75 to 55. And that’s implying the original speed readings are correct to begin with.

I’m not trying to jump on top of the pile, more just reminding myself why I don’t own a meter.

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What you might be not understanding here though is that when a prospective customer watches a review to help them make a purchase, they look to the data in AR15 video as being authoritative. Right or wrong, the videos are taken as fact. The majority of viewers will see “the meter says 124”.

I have zero experience with meters, and frankly don’t want any, but if you choose to use one, it really needs to follow an industry standard. The data is not only skewed, it’s incorrect.

The radar detector analogy someone made previously is a good one to remember: a speed reduction of 85 to 65 is a big difference compared to 75 to 55. And that’s implying the original speed readings are correct to begin with.

I’m not trying to jump on top of the pile, more just reminding myself why I don’t own a meter.

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Harp for 3 pages about the meter being no good and the numbers in the video being no good and then say you aren't chasing dB LOL.

The part in bold is flat out false.  Period.  Nobody who buys a can gives a flying fuck about what a meter says, they care about how the gun sounds when they shoot it with the can on. Not to mention they don't have a meter anyway, so they would never even see a dB number let alone give a shit about it.

Using the word feces instead of shit doesn't make your last sentence any more appropriate for a tech forum.  Not to mention the video in the OP is on the AR15.COM YOUTUBE CHANNEL.  So you're saying this forum is peddling shit.  Might wanna rethink that bold strategy cotton lol.

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10mm the meter is no fucking good because you can test cans side by side and not get the right results. Guns & Ammo tested our 338 Ultra against a bunch of cans. It metered the worst but they said it sounded the best. I know for a fact that of they cans they tested the closest to the Ultra is still 6dB louder. Yet we metered the loudest of the bunch but sounded noticeably quieter to those there.
What fucking good is that?

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At this point you're wasting your time, Ray. This Nobel laureate thinks that, because his shit meter managed to get a vaguely accurate NSR despite terrible precision, demonstrable equipment problems, and a small sample size, it somehow means he can use that to claim his results are "good enough." He's a charlatan who doesn't understand the theory behind silencer testing equipment nor basic principles of statistics. Just post a link to this thread every time he makes a dumb claim in the future and people will see for themselves. It's hilarious to watch him go toe to toe with the people who do this for a living like he's pulling the wool over their eyes.

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LOL that's hilarious. And it validates exactly what I said. If the difference is "huge and noticeable" then it greatly affects how the gun sounds. Which is the only thing people care about.

Glad we agree.

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AR15.com should reconsider using you to do their videos in the future. You are damaging their reputation.

Apparently, according to someone in this thread, you're an engineer and I find this remarkable. You're here arguing the value of accurate testing.  

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It's almost as if you should get lab numbers from a lab, and opinions from reviewers.  And use multiple data points to make your decision.

What an idea!

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It's almost as if you should get lab numbers from a lab, and opinions from reviewers.  And use multiple data points to make your decision.

What an idea!

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10mm if the 338 Ultra sounded much better ( they did put in the article that it sounded the best) and with Mil Spec equipment tests much better. What good is the LTX when it makes the 338 Ultra test louder? It shows that the meter is useless for testing gunshots.

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The people who "do this for a living" you guys keep referencing design and develop cans.  They don't review them on YouTube.  There is a difference.

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I'm going to ask these in here because of the knowledge level of those contributing so far...

Does an adjustable gas block reduce the at-ear dB number? I was watching a MAC video tonight of a can I have on order (YHM Turbo, x2) and it was ~14dB louder at the ear than the muzzle. I have some of mine tuned so they won't even cycle correctly without the silencer...and wondered if that would meter lower than a wide open gas block.

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Yep.  I've done a lot of work with this and I won't build up a rifle without using an adjustable gas block or carrier.  With the right can, it gets even better at-ear.  Really high backpressure cans that are optimized for muzzle performance capture a huge amount of pressure and allow it to go out the chamber when it opens. Sounds like the Turbo is in that ballpark. That's how the number gets so quiet at the muzzle.

If you can stop the chamber from opening too soon (adjustable block or carrier), then you're allowing some of that energy to make it out the muzzle.  But...  it'll make the muzzle reading higher.  It's a conservation of energy thing.  You can imagine how suppressor companies can play with this for their marketing numbers.  Many have done it unwittingly for years.  It's a dirty secret, but there you go.

This is also why dB chasers are mocked. I can dial a "super quiet" 556 suppressor to 140+ dB at the muzzle with a good block or carrier.  That might be a 10+ dB jump.  So for people to split hairs over a couple dBs between brands from wildly different test conditions and platforms is kind of funny to watch.

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@Mageever have you found the adjustable carrier or gas block to be better at the ear? I'm a big fan of the Bootleg carrier but was curious if it dumps more gas out of the port leading to higher at ear numbers vs. a gas block that may dump up front.

As always thanks for your insight in the forum.