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How quiet is "quieter"?

Discussion in 'Anything Airgun Related' started by Dag, Aug 28, 2014.

  1. Dag

    Dag Pro Poster

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    i've been reading some ads for the new Air Arms Q Tec silencer and something doesn't seem quite right.
    The Air Arms ad states that "Airgunners can enjoy a much quieter shooting experience, as the QTec is 7.5db quieter than the leading moderator on the market."
    Whereas an ad by Pellpax and other suppliers states the silencer is "10.92% quieter than the leading market moderator"
    Now it's some time since I was involved in noise levels but I understood a 6dB reduction to be a halving of noise level in which case 7.5dB would be significantly greater than a 50% reduction.
    So one ad would appear to show a noise reduction some 5 times greater than the other.
    It's highly likely that in my dotage I have got things wrong but perhaps those with a greater knowledge of noise levels and reduction could comment or put me straight.
    Dag:confused:
     
  2. oliver13

    oliver13 Donator

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    It depends what they're referring to, they probably aren't comparing like for like & will be rounding up & down like nobodies business anyway, plus the gun used will be a factor.
    If the original noise is 70ish db then that could explain the percentage?
     
  3. Kenbarcon

    Kenbarcon Donator

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    I would like to know which they class as the leading market moderator?
     
  4. Westphalian

    Westphalian Donator

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    Decibels are on a logarithmic scale and a reduction of 3 db is halving the noise level
     
  5. sej016

    sej016 Donator

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    dB is a relative measurement, not an absolute measurement. It is the relationship between one value (reference) and another.

    If the noise level was reduced from 70dB by 7.5dB, that represents an approximate 10% reduction in dB levels.

    But it represents a greater reduction in absolute levels, as a 3dB reduction is half the noise level. Another 3dB halves it again.

    The standard (absolute) reference sound pressure in air or other gases is 20 µPa, which is usually considered the threshold of human hearing (at 1 kHz).
     
  6. Dag

    Dag Pro Poster

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    I understood a reduction of 3dB to be a halving of the noise source rather than the noise level eg two lawnmowers or motorbikes reducing to one.
    I can understand the suggestion of 10% being 7dB when the original noise level was 70dB but that's a very low, almost a background, noise level. However it could be a copywriters lack of understanding logarithmic scales.
    Dag
     
  7. sej016

    sej016 Donator

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    That has to be 70dB relative to something else. In this case I would assume it to be against standard Sound pressure level (SPL) mentioned above.

    70dB is the level of a hand-held electric mixer.

    Traffic on a busy roadway at 10 m - 80 to 90 dB
     
  8. rkr

    rkr Keyboard Hero

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    If we want useful results we should compare one silencer against another in same enviroment at the same time period while using a recorder that can sample 96 kHz or more. Well, at least I've got rather useful results with that setup. The worst case is someone recording the noise level with their mobile phone app, when I tried that I got 30 dB variance over a long string of shots.
     
  9. Westphalian

    Westphalian Donator

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    Yes. The apps are a waste of time. I tried several and the variation was unbelievable
     
  10. Dag

    Dag Pro Poster

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    Some interesting replies guys but returning to my original question are these two statements compatible or not?
    Dag
     
  11. 177

    177 Donator

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    I compared one with a Weihrauch unit recently, both on identical .22 HW100 rifles, and the Weihrauch sounded noticeably quieter as measured by my Mk 1 ear.

    They have a different 'note' though, so it may be that an improvement in volume reduction is compromised by a 'sharper' sound at the muzzle.

    Three of us were there and we all agreed the Weihrauch sounded the quieter of the two.

    Marketing is full of absolutely meaningless statements in an effort to sell products.


    Example:

    "the QTec is 7.5db quieter than the leading moderator on the market"

    That tells us precisely nothing of value since the benchmark is not named.

    "Leading moderator" could (and probably does) simply refer to the most sold model, not necessarily the best performing model.

    I keep coming back to the how quiet are people wanting or expecting question.

    A nicely worked up PCP with a Weihrauch unit up front is close enough to silent for me to not be concerned too much about whether or not something else can actually deliver on the promises of being quieter.

    Having been downrange of my mate shooting a rig like this, I couldn't even tell he was shooting until the pellet impacted.

    Whatever Air Arms are claiming and however they choose to spin the 'facts' I hope for their sake the product lives up to expectation - I wouldn't give the same money a Weihrauch unit costs for it having heard them side by side, let alone the higher price they are asking.

    Some online reviews (not the shooting comic reviews, the ones where people have actually bought them) aren't overwhelming in their praise.

    The RFD I was at when I asked for a comparison said the same as me after he had let me hear them.

    So it might be quieter than a Weihrauch, but it certainly didn't sound like it to me.

    That's about as much as I can offer.
     
  12. Westphalian

    Westphalian Donator

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    i've yet to see (ok hear) anything beat a Weihrauch yet but i am about to get a Huggett in the next week or two and i'm hoping i haven't wasted my money
     
  13. mattyts

    mattyts Donator

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    1/2 UNF thread on a toilet tube,about the only thing that will make it quieter on comparison :p
     
    Last edited: Aug 29, 2014
  14. Stevie Darling

    Stevie Darling Sexual tyrannosaurus

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    To my ear the huggett was louder than the HW, but only at the shooters end!!

    but down range the huggett won the prize, the vents on the hugget prevents some of the blast going straight out the front, so less directed at your quarry:)
     
  15. rkr

    rkr Keyboard Hero

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    A correctly modified HW will more quiet than a standard HW. A good shroud will also be more quiet. Here are some noise measurements I did when I added Hugget type vents to one of my HWs:

    [​IMG]
     
  16. Stevie Darling

    Stevie Darling Sexual tyrannosaurus

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    How many, and what location were the holes mate:)
     
  17. rkr

    rkr Keyboard Hero

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    Six holes, right where the empty part of the tube starts for the first chamber from the muzzle. I had to use two layers of felt at the first chamber or it would blow too much air out.
     
  18. critter

    critter Donator

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    Thanks for that write up .177 you will have saved alot of people some cash.
    :rolleyes:
     
  19. Dag

    Dag Pro Poster

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    I'm going to return to this subject as I think even the airgun press can get things seriously wrong when it comes to the physics behind the subject of sound levels.
    As we have seen from some of the responses to my OP it would seem as though it is generally accepted that as the dB scale is logarithmic a reduction in sound level of 3 dB is a halving of the sound level ( I had thought it was a halving of the sound source eg one motor bike instead of two, and that a halving of sound level was 6dB).
    Anyway in this months Airgun Shooter the very silencer I originally referred to, ie the Air Arms Q-Tec in both .177 and .22, has been tested by Nigel Allen.
    The sound levels recorded without a silencer fitted were 112.4dBA and 112.8dBA respectively. With the Q-Tec silencer fitted the readings were 92.1dBA and 90.0dBA which gave sound reductions of 20.3dBA and 22.8dBA respectively.
    If each 3dBA is a halving over the previous level then a reduction of over 20dBA is a massive suppression of sound levels. Yet the article shows noise suppression as the % difference in readings and this results in reductions of 18.06% and 20.21% only.
    So is Mr Allen correct in his findings or is he doing Air Arms an injustice and their new silencer is in fact far more efficient than he thinks?
    Dag
     
    Last edited: Oct 12, 2014
  20. Stevie Darling

    Stevie Darling Sexual tyrannosaurus

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    The only way any of the aa silencers work, is when the rifle is empty:D

    I've never rated them, the rifles are superb, but silencers are Censored.
     

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