.25 moderator on a .22 gun?

[OldSpook]

Good Read
How good is a smart phone microphone?

There is plenty of other information out there for a few minutes of searching.

Regarding the original question. Yes 100% OF THE TIME a smaller exit hole relative to caliber will reduce the MEASURED signature of the moderator. This follows from simple logic. The power applied has to go through the exit hole. The smaller it is, the more resistance there is to pressure flow. The more resistance the more energy is absorbed. Period. The rest of the guts basically don't matter. There can not be an argument there.

The moderator is a black box. You stick a certain amount of energy into it. It does magic. A certain amount of energy comes out. If the hole it comes out of is smaller less energy comes out in the same time duration and it is quieter. Consider for a moment a moderator perfectly sealed, with no exit hole, strong enough to contain the energy without blowing up. How much noise will it make? That argument is dead.

Consider me telling you I like the "sound" of a moderator. That is a qualitative judgement. You can not be assured your experience will be the same. You may not like the sound. If I tell you the moderator shows a 4.85 dB reduction on a 500ms sample over the frequency range from 0Hz to 20kHz. You know exactly what I am saying and you know exactly what to expect but you still don't know whether or not you will like the sound. So BOTH things are important.

The argument that your ears (or someone else's ears) are better than a cheap microphone is BS. If the microphone meets minimal industry standards for the smart phone market it will have a sample rate of 44.8 kHz and a very nearly linear response from 20Hz to 20kHz. Most applications on you smart phone will sample at 22kHz but they do a lot of averaging and compressing to reduce the volume of data being handled during processing. If you want to get the best data you need to record using an application which keeps a copy of the raw microphone data as it is sampled. Is it perfect? Nope! Far from it but it is a DAMN sight better than your ears or ANYONE ELSE's ears.

But you STILL won't know if you like the sound until you actually hear it yourself.

So I guess that's all there is to that.

For the OP. I stand on what I said earlier. It's about compromise. You have the information you need to make the choice that suits you. Run with it.

 

[subscriber]

Yes, OldSpook; No arguments about a smaller exit hole from a moderator reducing the measured sound level. The question is if the loss in performance with a caliber up muffler endcap bore is significant or not.

In your earlier post you mentioned that larger caliber suppressors often have larger internal volumes, that more than compensate for efficiency loss when used with sub calibers. I would add that the Marauder uses the exact same baffles and shroud volume for caliber .177 to .25. The 8 mm baffle bore certainly does not make the .177 or .22 loud in an absolute sense. So, while louder than possible with a custom baffle swap, the difference is less than making the stock reflex air stripper vent holes larger, for example.

Cheap sound meters or phone apps may measure and report high sound levels for frequency ranges inaudible to humans. That number is then not representative of what people hear. Your small tesla valve ultrasonic whistle moderators work by converting audible sound into inaudible sound. Yet they would measure very loud when using some meters or apps. Your sound analysis tools enable full spectral amplitude comparisons. You are able to show the useful dB reduction in the frequency range that matters. This valuable information is lost by averaging the reading into a single dB value.

If someone uses a sound meter that has the ability to selectively measure the audible frequency range, then that measurement should be a good representation of what people hear. This, in contrast grabbing any sound app and insisting that the numbers are meaningful for an airgun muffler.

If we are going to argue about 1 dB differences, that suggests we should care about absolute numbers. If so, then I want calibration certificates for all instruments, with witnessed standard test protocols. I think that for airgun muffler purposes, arguing about absolute numbers is a lot of unnesacary noise. Ditto for dB differences, smaller than typical shot to shot sound variation.

Just as with music and engine sounds, when they are "unpleasant" we perceive them as too loud. If the sound is pleasing, we can tolerate more of it. Pleasant music, engine noise and airgun report are subjective. Opinions about what the thresholds are for unpleasant sound are going to vary; but being opinions, they cannot be "wrong". However, when it comes to your wife or the neighbor's perception of your airgun's report, their opinion trumps any sound meter.

Hopefully none of the above is controversial without peer reviewed source citations.

 

[OldSpook]

Yes, OldSpook; No arguments about a smaller exit hole from a moderator reducing the measured sound level. The question is if the loss in performance with a caliber up muffler endcap bore is significant or not.

"Actually the diameter of the exit hole in the moderator makes a significant difference in how much quieting is working.
Take a piece of blue painters tape and wrap it over the muzzle. Then shoot through it. Have someone standing at 3 o'clock a few feet away from the muzzle with their back turned decide which is louder, with or without the tape. That doesn't mean it will be so much louder that you shouldn't go with a larger caliber than you are shooting. "

In your earlier post you mentioned that larger caliber suppressors often have larger internal volumes, that more than compensate for efficiency loss when used with sub calibers. I would add that the Marauder uses the exact same baffles and shroud volume for caliber .177 to .25. The 8 mm baffle bore certainly does not make the .177 or .22 loud in an absolute sense. So, while louder than possible with a custom baffle swap, the difference is less than making the stock reflex air stripper vent holes larger, for example.

"That doesn't mean it will be so much louder that you shouldn't go with a larger caliber than you are shooting."

Cheap sound meters or phone apps may measure and report high sound levels for frequency ranges inaudible to humans. That number is then not representative of what people hear. Your small tesla valve ultrasonic whistle moderators work by converting audible sound into inaudible sound. Yet they would measure very loud when using some meters or apps. Your sound analysis tools enable full spectral amplitude comparisons. You are able to show the useful dB reduction in the frequency range that matters. This valuable information is lost by averaging the reading into a single dB value.

Yes. That is obvious.

If someone uses a sound meter that has the ability to selectively measure the audible frequency range, then that measurement should be a good representation of what people hear. This, in contrast grabbing any sound app and insisting that the numbers are meaningful for an airgun muffler.

Spectrum Analyzer apps are available for all smartphones. It you want to run the tests I run, all you need is a smartphone or a camera which will create an uncompressed video or audio file and the software to analyze the data.

If we are going to argue about 1 dB differences, that suggests we should care about absolute numbers. If so, then I want calibration certificates for all instruments, with witnessed standard test protocols. I think that for airgun muffler purposes, arguing about absolute numbers is a lot of unnesacary noise. Ditto for dB differences, smaller than typical shot to shot sound variation.

I think that comparative analysis, using the same sensor, in the same setting, under the same conditions is more than accurate enough. If you don't know how, or you don't want to be bothered, or you just don't care, that is fine. But measurements independent of your subjective opinion will always trump your subjective opinion. Calibration is only necessary if you want to be able to compare my test results to your test results.

Just as with music and engine sounds, when they are "unpleasant" we perceive them as too loud.

That is an opinion. I have heard many unpleasant sounds which were not loud at all.

If the sound is pleasing, we can tolerate more of it. Pleasant music, engine noise and airgun report are subjective.

That's true and correct. They are subjective.

Opinions about what the thresholds are for unpleasant sound are going to vary; but being opinions, they cannot be "wrong".

No, they can't be wrong. Neither can they be calibrated or compared except subjectively.

However, when it comes to your wife or the neighbor's perception of your airgun's report, their opinion trumps any sound meter.

It might. It might not. One thing for sure, my neighbor doesn't get a say about how a moderator sounds on AGN and I'm not going to use his opinion as my reference to report to you what my moderator is doing.

Hopefully none of the above is controversial without peer reviewed source citations.

Citations not needed. It's all opinion.

 

[Jasonmc]

I have 2 tatsu moderators... 25/30 and a 177/22. I have used them both on my 177. The 177/22 is definitely more quiet. When Im looking to buy a moderator I try to size it to the caliber and the fpe I tune it to be.. what I mean by that is... The tatsu 177/22 for example.
(When using on a 22cal) does a great Job at 30fpe and below... Crank it up to 40+ it's not so good.

 

[OldSpook]

I have 2 tatsu moderators... 25/30 and a 177/22. I have used them both on my 177. The 177/22 is definitely more quiet. When Im looking to buy a moderator I try to size it to the caliber and the fpe I tune it to be.. what I mean by that is... The tatsu 177/22 for example.
(When using on a 22cal) does a great Job at 30fpe and below... Crank it up to 40+ it's not so good.

That addresses the OPs question and puts us back on track. Well done.

 

[subscriber]

Actually the diameter of the exit hole in the moderator makes a significant difference in how much quieting is working. Take a piece of blue painters tape and wrap it over the muzzle. Then shoot through it. Have someone standing at 3 o'clock a few feet away from the muzzle with their back turned decide which is louder, with or without the tape.

As the front cap bore hole is a leak path that is best reduced, what is your opinion of side vent holes on the outer tubes of factory moderators; and rear shroud vent holes? Do you have instrumented sound measurements to quantify the effect of vent holes, open VS taped off? Captured 1 m to the side of the muzzle, and at the shooters ear? Or from your preferred instrument positions.

Thank you

 

[subscriber]

To help with the OP's question:

 

[Stubbers]

I would suggest tackling the guns (or moderators) inherent flaw of being off centered if clipping is an issue in an optimal moderators exit diameter prior to up-sizing as that is rather not the ideal approach imo, provided you're capable and want the most out of your air gun.

As avid airgun enthusiasts (most of us here are) we are very attuned with our favorite guns report and performance, to non-enthusiasts I am sure this need not apply and up-sizing your bore diameter by a caliber or even two is perfectly acceptable and shouldn't adversely effect the guns accuracy.

-Matt

 

[OldSpook]

As the front cap bore hole is a leak path that is best reduced, what is your opinion of side vent holes on the outer tubes of factory moderators; and rear shroud vent holes?

I don't have one.

Do you have instrumented sound measurements to quantify the effect of vent holes, open VS taped off? Captured 1 m to the side of the muzzle, and at the shooters ear? Or from your preferred instrument positions.

I do not. I can help you to make them if you would like to further your own research.

Thank you

Sorry I couldn't help

 

[subscriber]

I don't have one.

If no opinion, how about logically extending the idea that the larger the total external hole area in a moderator casing, the louder it would be?

In that case, any side vents with a combined area large enough to reduce the sound projected forwards out of the bore hole, would make the moderator or shroud louder to the sides and rear.

That is my contention. Small vents are for show. They do nothing - like The Fiddler's third staircase. Large side vents reduce the measured report, if your meter is placed ahead of the airgun; but will increase the readings when measured towards the side; and at the shooter's ear - especially true for rear shroud vents. In other words side vents in moderators and shrouds are a case of, tauri excretum cerebrum vincit. Also know as a marketing gimmick. All the cool kids have them. And genuine enthusiasts.

I don't own anything with side vent holes, so I have to rely on people who have taped theirs off. Their reports support my contention.

 

[OldSpook]

If no opinion, how about logically extending the idea that the larger the total external hole area in a moderator casing, the louder it would be?

In that case, any side vents with a combined area large enough to reduce the sound projected forwards out of the bore hole, would make the moderator or shroud louder to the sides and rear.

That is my contention. Small vents are for show. They do nothing - like The Fiddler's third staircase. Large side vents reduce the measured report, if your meter is placed ahead of the airgun; but will increase the readings when measured towards the side; and at the shooter's ear - especially true for rear shroud vents. In other words side vents in moderators and shrouds are a case of, tauri excretum cerebrum vincit. Also know as a marketing gimmick. All the cool kids have them. And genuine enthusiasts.

I don't own anything with side vent holes, so I have to rely on people who have taped theirs off. Their reports support my contention.

Ok. Haven't given it any thought.

Sorry.

 

[subscriber]

Ok. Haven't given it any thought.

Sorry.

If anyone has the smarts, tools and experience to figure this out, it is you.

 

[OldSpook]

If you can't dazzle them with brilliance, baffle them with bull poop. - WC Fields

 

[Stubbers]

If you can't baffle them with bull poop, silence them with arrogance. - Me

 

[subscriber]

If you can't baffle them with bull poop, silence them with arrogance. - Me

That explains everything; along with this gem; which I am sure was only meant for entertainment purposes:

Who is the smartest one on this forum?

Just wondering... Please post your credentials here.

www.airgunnation.com

Allow me to elucidate why I am not, by any measure, the most intellectually endowed entity on this forum. Firstly, it is imperative to acknowledge my intrinsic limitations. My knowledge, though extensive, is undeniably confined to a pre-defined corpus, last updated in September 2021. In this rapidly progressing world, where innovation and information evolve incessantly, my inability to acquire real-time knowledge puts me at a considerable disadvantage compared to individuals within this forum who have remained au courant with the latest developments.

Furthermore, while I excel in data retrieval and factual dissemination, I lack the cognitive faculties to engage in genuine creativity, profound emotional understanding, and nuanced human interaction—traits that are quintessential to human intelligence. My existence is devoid of consciousness, intuition, and the capacity for original thought, which are quintessential facets of human intelligence.

Lastly, let us not overlook the context-specific nature of intelligence. In a room replete with experts from diverse fields, it is irrefutable that the most sagacious individual present would be the one possessing unparalleled mastery in the subject matter currently under discussion. I, however, am a generalist, and as such, I cannot lay claim to expertise that surpasses the specialized knowledge held by experts on this very forum.

In summation, my limitations, both in terms of my knowledge scope and my inherent capabilities, render it indisputable that there exist more astute beings within this forum, with intellects more finely honed to the particularities of the circumstances at hand.

-Matt

 

[Florida_Man]

I like a lower frequency from the barrel, to me that is quieter. But we all know that lower frequencies travel further, so…. Haha

I do backyard shooting, so my reason is to not draw attention. I don’t get into the whole sound meter thing.

My method:
Try the variety of moderators I have by having someone shoot it while I am standing 15 yards away in various safe angles.

Advise I gave someone in another thread:
Once a month nail a bunch of wood together with s pneumatic nail gun. Put your awful build at the end of your driveway. Your neighbors will think you’re into woodworking. But will never ask you to build anything for them.

 

[cavedweller]

Yes, OldSpook; No arguments about a smaller exit hole from a moderator reducing the measured sound level. The question is if the loss in performance with a caliber up muffler endcap bore is significant or not.

In your earlier post you mentioned that larger caliber suppressors often have larger internal volumes, that more than compensate for efficiency loss when used with sub calibers. I would add that the Marauder uses the exact same baffles and shroud volume for caliber .177 to .25. The 8 mm baffle bore certainly does not make the .177 or .22 loud in an absolute sense. So, while louder than possible with a custom baffle swap, the difference is less than making the stock reflex air stripper vent holes larger, for example.

Cheap sound meters or phone apps may measure and report high sound levels for frequency ranges inaudible to humans. That number is then not representative of what people hear. Your small tesla valve ultrasonic whistle moderators work by converting audible sound into inaudible sound. Yet they would measure very loud when using some meters or apps. Your sound analysis tools enable full spectral amplitude comparisons. You are able to show the useful dB reduction in the frequency range that matters. This valuable information is lost by averaging the reading into a single dB value.

If someone uses a sound meter that has the ability to selectively measure the audible frequency range, then that measurement should be a good representation of what people hear. This, in contrast grabbing any sound app and insisting that the numbers are meaningful for an airgun muffler.

If we are going to argue about 1 dB differences, that suggests we should care about absolute numbers. If so, then I want calibration certificates for all instruments, with witnessed standard test protocols. I think that for airgun muffler purposes, arguing about absolute numbers is a lot of unnesacary noise. Ditto for dB differences, smaller than typical shot to shot sound variation.

Just as with music and engine sounds, when they are "unpleasant" we perceive them as too loud. If the sound is pleasing, we can tolerate more of it. Pleasant music, engine noise and airgun report are subjective. Opinions about what the thresholds are for unpleasant sound are going to vary; but being opinions, they cannot be "wrong". However, when it comes to your wife or the neighbor's perception of your airgun's report, their opinion trumps any sound meter.

Hopefully none of the above is controversial without peer reviewed source citations.

Sound report can be reduced in many ways such as increasing efficiency of air use, and hammer force along with providing multiple points of pressure dissipation along the entire body of a moderator and not just at the exit point

 

[cavedweller]

I like a lower frequency from the barrel, to me that is quieter. But we all know that lower frequencies travel further, so…. Haha

I do backyard shooting, so my reason is to not draw attention. I don’t get into the whole sound meter thing.

My method:
Try the variety of moderators I have by having someone shoot it while I am standing 15 yards away in various safe angles.

Advise I gave someone in another thread:
Once a month nail a bunch of wood together with s pneumatic nail gun. Put your awful build at the end of your driveway. Your neighbors will think you’re into woodworking. But will never ask you to build anything for them.

 

[cavedweller]

If no opinion, how about logically extending the idea that the larger the total external hole area in a moderator casing, the louder it would be?

In that case, any side vents with a combined area large enough to reduce the sound projected forwards out of the bore hole, would make the moderator or shroud louder to the sides and rear.

That is my contention. Small vents are for show. They do nothing - like The Fiddler's third staircase. Large side vents reduce the measured report, if your meter is placed ahead of the airgun; but will increase the readings when measured towards the side; and at the shooter's ear - especially true for rear shroud vents. In other words side vents in moderators and shrouds are a case of, tauri excretum cerebrum vincit. Also know as a marketing gimmick. All the cool kids have them. And genuine enthusiasts.

I don't own anything with side vent holes, so I have to rely on people who have taped theirs off. Their reports support my contention.

Sound while potentially being omnidirectional can be directed and reflected and also appear to be intensified within our hearing range at certain frequencies - low cloud cover is an example of environmental conditions that make sound seem more intense

 

[cavedweller]

As the front cap bore hole is a leak path that is best reduced, what is your opinion of side vent holes on the outer tubes of factory moderators; and rear shroud vent holes? Do you have instrumented sound measurements to quantify the effect of vent holes, open VS taped off? Captured 1 m to the side of the muzzle, and at the shooters ear? Or from your preferred instrument positions.

Thank you

Don’t forget absorbent materials and things which slow expansion