I tested some moderators today. There was some problem with viewing the link IN LINE. There is no problem with viewing it if you open it via YOUTUBE. 
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Moderator Test
- Thread starter OldSpook
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Good testing. FWIW your two were noticeably quieter in the video (at least over my speakers), than the two Donny's YET dB were more or less same. Are your's smaller volume than the Donny's? IIRC you worked out the moderator efficiency measurement system (dB/volume = efficiency). Regards, Badger
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Our ears don't respond to different frequencies the same way that a microphone does. The higher the frequency more difficult it is for us to hear it. That's far less true with the microphone. One of the things that happens in a moderator is that some frequencies are converted up or down depending upon the shape and volume of the moderator.
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I agree, but what the average human or animal ear hears is what concerns me and although the Db differences were minimal, your moderators did sound just a bit quieter. Which makes me wonder how a tree rat, chipmunk, starling, etc hears it? (smile)
How other human ears hear it because I shoot in an urban environment and how my pests hear it because that may mean getting more shots when multiple targets present themselves within a short time.
Thanks for the video!
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Yep, some things we need to be trained to be able to recognize. Sometime the training takes longer than we have
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GREAT work yours ,as others noted , did sound quieter to me also .
and good point about what the pests hear
and good point about what the pests hear
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So I need to train my neighbors and the pests I shoot to not hear my airgun? LOL!Yep, some things we need to be trained to be able to recognize. Sometime the training takes longer than we have
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So I need to train my neighbors and the pests I shoot to not hear my airgun? LOL!
Exploit the training they already have... Upvote 0
I would be interested in further study of your moderators. Specifically, on a .177 rifle, use measure the effective reduction of a tight bore to pellet ratios vs. a loose bore to pellet ratio.
i.e. - make a tight fit .177 moderator - measure dB.
test same gun and pellet through at .22 moderator
test same gun and pellet through a .25 moderator and a .30 moderator.
Your current set up would be a good platform for that test, and you know the guy who makes the moderators
I am stubbornly waiting for someone to empirically demonstrate the reduction losses due to bore oversize.
Thanks for any effort you put into the research. I will happily buy you a cuppa fancy coffee for your efforts.
i.e. - make a tight fit .177 moderator - measure dB.
test same gun and pellet through at .22 moderator
test same gun and pellet through a .25 moderator and a .30 moderator.
Your current set up would be a good platform for that test, and you know the guy who makes the moderators
I am stubbornly waiting for someone to empirically demonstrate the reduction losses due to bore oversize.
Thanks for any effort you put into the research. I will happily buy you a cuppa fancy coffee for your efforts.
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Jim,
that is truly one of the tests I have never seen done.
It's much talked about — whether the silencer bore size makes much of a difference — and how much. And there are voices on both sides. Mostly backed up by subjective guesswork and speculation, I assume.
But measured, with however simple of a method, nope. Not seen.
To increase the usefulness of the test I'd suggest to also do the same test starting with a .22cal gun. The guns should be tuned efficiently as not to waste air (and increase noise). And probably at a power level typical for that caliber.
Once we have the test results — I think one of the specs that we need to collect and publish is the actual bore size of the silencers available.
If the test discovers that it does make quite a bit of a difference, we might want to rethink using certain brands that advertise for example ".177/.22cal" but have actual bore sizes that would allow using it with a .25cal gun where the silencer is screwed on straight. If the test discovers that it does not make much of a difference, we might want to rethink buying silencers for every caliber we own. Just buy a .25 to cover .25, .22, and .177. Done. Hundreds of dollars saved. This is exciting. As we have guns with so much more power, now we need silencers with so much more quiet!
Matthias
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@JimNM well it would seem to me the thing to do to test that would be to make a small moderator that was hollow with different size exits what do you think?
To that end I have drawn up five moderators exactly the same except for the size of the port in the muzzle. I'll start printing them either tonight or tomorrow.
The ports on them are 5.5mm, 6.5mm, 7.5mm, 8.5mm and 9.5mm. They are 29mm x 80mm.
The test will give us an idea of what port size does/does not do. There are a lot of variables which are isolated out of the test. As for learning anything else from the test, I hope there isn't anything else we can learn from it. One thing I've observed, if you change anything in the test other than the control variable all bets are off as far as meaningful results are concerned.
So I hope to get you some data later in the week.
Mike
To that end I have drawn up five moderators exactly the same except for the size of the port in the muzzle. I'll start printing them either tonight or tomorrow.
The ports on them are 5.5mm, 6.5mm, 7.5mm, 8.5mm and 9.5mm. They are 29mm x 80mm.
The test will give us an idea of what port size does/does not do. There are a lot of variables which are isolated out of the test. As for learning anything else from the test, I hope there isn't anything else we can learn from it. One thing I've observed, if you change anything in the test other than the control variable all bets are off as far as meaningful results are concerned.
So I hope to get you some data later in the week.
Mike
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I made a moderator with a .22 exit , it worked nicely on .177 , not great . so i put a piece of blue painters tape 2x over the end and shot through ,it was a bit more quiet but no measurement was taken as i do not have a device and b4 app's . Now back to the question with .180 center hole or .25 center hole with .178 hole end cap ? P.S. a wadcutter cuts a fairly clean hole in painters tape .
Stan
P.S.S. i think the manufactures make larger end cap holes for clipping issues with avg. people screwing them on whatever guns .
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I am happy that I am not alone in this quest. I have long been bemused that some enthusiastic people argue about the need to oversize the moderator and others insist that any extra clearance is absolutely detrimental to the reduction of sound impulse energy.
I have never seen a moderator list the inside dimensions of their bore. Without a starting point, all comparisons are baseless.
I suggested the .177 simply to maximize the sample size available. I shoot .22 and .25 with a .30 Donny moderator on the .22, and a .25 Donny on the .25 rifle. The form factor of the .30 fits the .22 rifle better and I could not detect a difference in the sound impulse between the two. I don't care at all what brand stuff is, I am only concerned with results.
Shoot'em good (and quietly)
I have never seen a moderator list the inside dimensions of their bore. Without a starting point, all comparisons are baseless.
I suggested the .177 simply to maximize the sample size available. I shoot .22 and .25 with a .30 Donny moderator on the .22, and a .25 Donny on the .25 rifle. The form factor of the .30 fits the .22 rifle better and I could not detect a difference in the sound impulse between the two. I don't care at all what brand stuff is, I am only concerned with results.
Shoot'em good (and quietly)
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Moderator Exit Hole Test
@JimNM ;) Here you go. Interesting result. I converted the dB readings to KW so that I would have a linear measurement to put in the graphs as that is much more intuitive for most folks. The high spike on the left of the x axis is the bare rifle with no moderator. You will also see some data...
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f somebody wishes to do this test, be sure to measure the true barrel diameter after the choke right at the muzzle. To do that accurately, you should use a pin gauge set in a go/no go scenario. It is that diameter that I then add.020" for moderator bore size. Of course, if you don't measure the barrel exit diameter, the test would not very relevant.
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The test has been done. There is a link to the results in the post above yours. Why do you think it is necessary to measure the bore diameter of the rifle?
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Was that a hammer hitting? how many decibels coming from the hammer? Next time you can wrap the gun in a blanket multylayer, so what you measuring would be a sound only from muzzle end?
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