A little help with suppressor db reduction

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Ryanxia

Ryanxia

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Comparing some different cans for my next purchase and had a question that I didn't seem to find the answer to in my searches (I think I wasn't wording the question right).

I'm seeing suppressors listing db reductions and trying to figure out how big of a difference 30db reduction to 39db reduction is.

I primarily want to get a 300 blackout setup down to as quiet as some of the videos I've seen where the trigger reset is as loud as the gunshot.
I know the ammo/barrel length has a lot to do with it, but is that level of quiet achievable with a suppressor that reduces 30db? Or would I need to purchase one that reduces 36-39db?

Thanks for any info.
 
The difference between 30 vs 39 dB reduction is large, and will be immediately detected by the ear. Also, dB reduction ratings aside ultimately sound reduction is greatly influenced by platform. A bolt gun that has zero moving parts and no place for gas to escape besides the muzzle upon firing will always be quieter than a semi auto due to a combination of action noise and escaping gas. Out of curiosity which silencer are you looking at that offers 39 db reduction?
 
I'm looking at the Gem-tech GMT 300BLK which lists 39db but is for 300 blackout only (no .308/5.56) as well as the AAC 762-SDN-6 which lists 39db but is rated for other calibers.
My main goal is to get .300 blackout as quiet as possible (out of an AR15, 7.5" barrel) but I'd like to be able to run it on other setups.

I've seen some other suppressors from the same manufacturers at almost half the price but are listed at 30db instead of 39db and I'm just not sure how to quantify the difference between the two.
 
Posted db reductions by silencer companies often can't be trusted unless you know that they followed the proper procedures and financed the proper equipment to get the scientifically verified numbers. From my understanding (no actual experience), it's quite expensive and very specific to get the proper numbers and is one of the last things that should be considered in comparing silencers. Look more at materials, attachment methods, warranty and dimensions. Even if 2 suppressors are dimensionally similar, they may have different tones and 1 will sound quieter to you than the other because of your specific hearing characteristics. Your personal hearing may be better attuned to 1 suppressor than the other, so 1 will sound better, or quieter, than the other even though they are "rated" similarly. db reduction numbers is 1 of the worst, and most difficult to verify methods, to compare silencers.

I've seen some "bubba" videos that used some kind of equipment to get decibel numbers and they shot a silenced .22 with a suppressor and without a suppressor and just closing the action to prepare for firing gave them 116 decibels. The guy standing outside on a pair of crutches fired the suppressed rifle and came up with a 119 reading. Was it done scientifically? Nope, but people "test" their suppressors like that and publish their numbers and it's hard to refute them.

Good luck with your selection. Don't get hung up on "best" and look at features that you want in the suppressor. Often, "best" is very subjective.
 
Thanks for the suggestions Loco, certainly material, attachment, dimensions were the first things I considered, but all those being equal (or similar) it comes down to db reduction. And while their methods may not be the best, they use the same ones on each of their products, so a company that has a 39db suppressor and a 30db, they are determined using the same method.

I'm just wondering how much the +/- 9db makes a difference.
 
I'm just wondering how much the +/- 9db makes a difference.
Click to expand...

A 9dB difference is HUGE ... but the question is whether or not a 9dB difference actually exists. As we all know, a 3dB difference means doubling or halving the volume since dB is a logarithmic scale.
 
1858 said:
A 9dB difference is HUGE ... but the question is whether or not a 9dB difference actually exists. As we all know, a 3dB difference means doubling or halving the volume since dB is a logarithmic scale.
Click to expand...
I know it's based on a logaritmic scale, but I've also been told that to the ear 9db isn't hardly any difference (which I'm skeptical about but its from an experienced suppressor shooter/owner).

And the reason I think the 9db difference actually exists between two suppressors is that I'm comparing different suppressors from the same company (so a company advertises one for sale at 30db and one at 39db, doubt they are using different testing for the two products).
 
What is the hearing ability of the individual claiming that 9dB makes no difference? Without that information it's a meaningless statement and possibly meaningless with it. That individual could have moderate to severe hearing loss and not even know it. As for the dB ratings coming from the same company and therefore being accurate, that's a huge assumption. I have seven suppressors from AAC so I'm obviously a satisfied end user of their products.

There's an excellent physics paper on hearing here ... and here's a snippet. The paper shows that human hearing is incredibly complex. We're not good at absolutes or steady state, we're better at detecting differences. For example, we feel acceleration but not velocity.


"Because human hearing is not flat with frequency, the perceived, or apparent loudness of a sound depends on frequency, and also on the actual intensity I (in Watts/m2), or equivalently, the actual loudness LI (in dB) {or sound pressure level LP = SPL (in dB) of the sound."
 
Ryanxia said:
Thanks for the suggestions Loco, certainly material, attachment, dimensions were the first things I considered, but all those being equal (or similar) it comes down to db reduction. And while their methods may not be the best, they use the same ones on each of their products, so a company that has a 39db suppressor and a 30db, they are determined using the same method.

I'm just wondering how much the +/- 9db makes a difference.
Click to expand...
Ok, didn't know you were comparing suppressors from the same company. It seems like it would be a safe assumption that the difference between the suppressors would be legitimate, so I assume you're looking at a cost/benefit analysis of the price difference to 9db and wondering if the 9 db is worth the (for example, straight out of the air) $300 difference in price? Hard to say without actually hearing the suppressors. Don't know what the difference is in reality. 1858 is also right in that it's still an assumption that they collected the "data" correctly. Theoretically, that's a big difference. Care to share the company that makes the claim?
 
1858 - The hearing of this individual is fine, but of course there's a lot of factors when comparing two different suppressors.

Loco - Gem-Tech and AAC both have suppressors listed at 30db and 39db reduction.
For example, AAC has the 762-SD (30db) and the 762-SDN-6 (39db in 300BLK), both steel, same attachment, one at half the price. (Don't care about the difference in length)
Do I spend the extra money for that listed 9db or not? (And this is for a 300 blackout so the 39db applies).
 
For example, AAC has the 762-SD (30db) and the 762-SDN-6 (39db in 300BLK), both steel, same attachment, one at half the price. (Don't care about the difference in length)
Do I spend the extra money for that listed 9db or not? (And this is for a 300 blackout so the 39db applies).
Click to expand...

I have the AAC 762-SDN-6 not that it's relevant to your choice. What is relevant is that AAC doesn't provide a dB reduction value for the 762-SD with 300 BLK. However, if you compare the M80 data for the 762-SD to the 7.62 NATO for the 762-SDN-6 (basically the same thing) they show -30dB and -25dB respectively. So on paper the cheaper suppressor has the better sound reduction which isn't shocking given that it's 1-1/2" longer and 3oz heavier. The 762-SDN-6 is full auto rated, lighter and shorter and that's what you're paying for. I would choose the 762-SDN over the 762-SDN-6 unless I was concerned about length and full auto use.
 
Ryanxia said:
Comparing some different cans for my next purchase and had a question that I didn't seem to find the answer to in my searches (I think I wasn't wording the question right).

I'm seeing suppressors listing db reductions and trying to figure out how big of a difference 30db reduction to 39db reduction is.

I primarily want to get a 300 blackout setup down to as quiet as some of the videos I've seen where the trigger reset is as loud as the gunshot.
I know the ammo/barrel length has a lot to do with it, but is that level of quiet achievable with a suppressor that reduces 30db? Or would I need to purchase one that reduces 36-39db?
Click to expand...

Decibels are measured on a logarithmic scale: the usual rule is that a 3 dB difference is approx 2x as loud [perceptually.] So that 30 vs. 39 dB reduction means that if the latter can suppresses the shot completely [we'll take the proverbial "could hear a pin drop" as the perceptual limit of hearing], the louder can would be about 8x louder, or say, the sound of someone crumpling a gum wrapper.

Ie: for most intents & purposes, the 1st 30dB reduction is the key. Quieter is always better, but what is the co$t difference?

Really suggest you read vol.1 of Silencer History & Performance to get a better idea of what you need.
 
Aside from needing to assume the dB numbers are correct, you still have the problem of comparing apples to oranges.

For example, your numbers for the AAC 762-SD of 30dB reduction is for the M80 7.62 round, while the 39dB for the 762-SDN-6 is for the 300BLK (they say 25dB reduction for the 7.62 NATO, _assuming_ M80 too).

So does that mean that the SD will be even quieter than the SDN-6 with 300BLK since it is quieter with 7.62 NATO? Can't say for sure. Too many variables.

SilencerForum used to post nice comparisons. Best are the head-to-head tests where all of the variables (ammo, atmospheric conditions, etc) are minimized. Seem to have quit doing them quite a while back, unfortunately.

SilencerCo's original videos were good comparisons too, done under identical conditions with proper measuring equipment. Won't help here though. They've also let the advertising guys take over. Too much fluff in their videos now.

Do you have a dealer with demos?

What suppressors and barrel lengths were they using in the videos you are talking about? Using videos to compare sound levels opens another huge can of worms though. Inaccurate sound reproduction, clipping, possible doctoring, etc.

That being said, when comparing true numbers, everything else being equal, I'd be willing to spend a good chunk of change more for an extra 9dB.
 
Last edited:
Thanks for all of the information and links, I've got some reading to do. :)
I'm trying to make the right choice since I think I've only got time to get one approval in before the (potential) changing of the laws regarding trusts (just basing it on the worse case scenario of May 31st).

Thanks again, and any more info is always appreciated. :)
 
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