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Post by Zinger on Apr 28, 2014 6:54:25 GMT -5
While there may not be a "silent" gearbox, I've seen and heard a few that have come close. In the next few weeks I plan to pick up this Classic Army SR-25 (http://www.evike.com/products/45340/). My goal like anyone with this style rifle is to build a dmr, but my other goal is to keep it quiet. (I'm keeping this build under 360fps for cqb play. I plan to eventually buy another lower reciever that will have a 450-550fps outdoor setup) I know how to get a good trigger response and make it accurate, but how can I keep it quiet. I've heard good and bad things about sorbopads, and I'm sure a good shim will also cut noise, but are there any other suggestions?
One other quick thing, I have always known classic army to use an extended v2 gearbox in their SR-25, but evikes page says just v2. Have they switched to a standard v2 or is it just a typo on evikes part?
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Post by Shadow (314) on Apr 28, 2014 20:40:02 GMT -5
Get a Polarstar?
But from what you're saying, I think your best options are to get not jsut good, but great quality gears and shim them PERFECTLY. Helicals are difficult to shim and may make more noise because of that. Make sure your gearbox is clean and lubed, consider a Sorbo, perfect your AOE, have a quality motor that can push everything with relative ease, and stuff dampening materials around the gearbox where it can fit and be safe.
For an AEG, I think that's all you can do.
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Snarf
New Member
Ambidextrous selector switches are the bane of my existence
Posts: 560
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Post by Snarf on Apr 28, 2014 20:50:47 GMT -5
I think that a silencer is also a key part, depending on the volume balancing of your barrel to cylinder. From my experience, most of the noise from an AEG comes right out of the barrel. At long ranges you don't hear the whine of the gearbox (hopefully!), you hear the compressed air forcefully exiting the barrel. But if you want it really silent at close range, I don't really know. Take 'em all out with the first burst I guess.
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Post by Zinger on Apr 28, 2014 20:57:54 GMT -5
Get a Polarstar? But from what you're saying, I think your best options are to get not jsut good, but great quality gears and shim them PERFECTLY. Helicals are difficult to shim and may make more noise because of that. Make sure your gearbox is clean and lubed, consider a Sorbo, perfect your AOE, have a quality motor that can push everything with relative ease, and stuff dampening materials around the gearbox where it can fit and be safe. For an AEG, I think that's all you can do. Ok thanks, I figured someone would recommend a polar star, and to be honest I'm sure it will end up as one somewhere down the road. Thanks for the advice though, I'll defiantly take that info into consideration. |
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Post by Zinger on Apr 28, 2014 21:03:29 GMT -5
I think that a silencer is also a key part, depending on the volume balancing of your barrel to cylinder. From my experience, most of the noise from an AEG comes right out of the barrel. At long ranges you don't hear the whine of the gearbox (hopefully!), you hear the compressed air forcefully exiting the barrel. But if you want it really silent at close range, I don't really know. Take 'em all out with the first burst I guess. I've always been skeptical about airsoft suppressors, in my opinion they just change the sound characteristics and not really dampen the noise, but I already have one on my list of things to buy for the rifle, so I guess I could try it out and see if it truly does make a difference. Hopefully with the barrel and hop up set up I plan to use I won't miss to often up close, so I'll be taking your last bit of advice to heart. Thanks again. |
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T6e9a
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Back in business
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Post by T6e9a on Apr 28, 2014 21:33:46 GMT -5
A hollow silencer maybe, and fill it with some sort of soft foam or other material that might dampen the sound. Silencers themselves in airsoft are generally for looks or to hide longer inner barrels, but if you don't have a protruding inner barrel, a foam filled silencer may be able to help a little. Nothing drastic, but with any luck a little.
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Snarf
New Member
Ambidextrous selector switches are the bane of my existence
Posts: 560
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Post by Snarf on Apr 28, 2014 21:47:48 GMT -5
I meant an actual sound suppressing barrel extension. You just need a tube that will absorb sound and air vibrations. I know you can DIY it and come up with a quite effective one, and guides are all over the internet, but I'm pretty sure it's illegal.
Definitely not an airsoft silencer though. Those are just for looks.
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Post by Zinger on Apr 29, 2014 6:44:53 GMT -5
Ok, I see what your saying now. Yeah I'll more than likely extend the inner barrel into the mock suppressor. I should have an extra inch or two I can mess with. I think I'll just keep my focus on the gearbox itself maybe tinker with the suppressor later.
I'm transitioning back from GBBR (I'm tired of fixing it all the time, with college coming, I don't want to have to keep paying for replacement parts and run a more reliable gun). So I really just want to minimize the whine I hear from it. I think I'll take the advice for the basic tune-ups, sorbopad, high quality gears, mosfet and other parts for a high torque/quick trigger response. I'll have to crunch the numbers and decide whether it's worth building the gearbox up or just throwing a p* in it.
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Post by X on Apr 29, 2014 8:50:10 GMT -5
Keep in mind the further you extend the barrel into a foam filled suppressor the less effective it will be. I can say from experience that suppressors make the biggest difference for long range sound. I think it's because the pop of air is an acoustic impulse and as such it contains low frequency sound that the gearbox whine does not. Lower frequencies tend to travel further than higher frequencies. The foam does a good job of dampening the expanding air coming out of your gearbox. With that in mind I surmise that doing a good job of volume matching your cylinder to barrel will also help.
Sent from my XT1080 using proboards
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Post by Zinger on Apr 29, 2014 15:08:01 GMT -5
Keep in mind the further you extend the barrel into a foam filled suppressor the less effective it will be. I can say from experience that suppressors make the biggest difference for long range sound. I think it's because the pop of air is an acoustic impulse and as such it contains low frequency sound that the gearbox whine does not. Lower frequencies tend to travel further than higher frequencies. The foam does a good job of dampening the expanding air coming out of your gearbox. With that in mind I surmise that doing a good job of volume matching your cylinder to barrel will also help. Sent from my XT1080 using proboards I doubt that I'll actually try modifying the suppressor to add foam or any other suppression method, I'm just going to focus on the gearbox and do what I can there. Now my area of expertise is GBB, but I know my way around a gearbox, but some of these concepts are not the most familiar to me. Like matching the cylinder to barrel, is that where the cylinder needs to push enough volume of air to propel the BB to the very end of the barrel? If so I believe the sr-25 has an extended piston, cylinder, etc. shouldn't that have enough volume to propel the BB down a 510mm barrel? Is that even the concept you guys are mentioning? Or possibly something I don't know yet. |
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Post by MayhemXXXFrosty (AndrewMp5k) on Apr 29, 2014 17:33:48 GMT -5
Cylinder to barrel theory is based on the correct cylinder to barrel length. Basically depending on your length barrel should dictate the right cylinder "volume". 400mm +/- (maybe less depending on setup) should basically have a "non"-ported cylinder. By having a non-ported cylinder the piston pushes more air down the barrel and has more force to get the BB to the end of it and out before the piston begins drawing back and creates a vacuum thus sucking back on the BB causing a backdraft or backspin. In a nutshell too much cylinder volume causes overspin where-as too little cylinder volume causes backspin. Hope I explained that right #overtimeisoverrated.
Note that every setup is different in some way or another. So this "theory" is not a "law" for a reason. If your piston isn't getting good compression for some reason or same with your hop-up you may benefit from "over"-voluming your cylinder (I've seen this on M4's with 363mm barrels with pretty mediocre compression do well with non-ported cylinders).
From what I've seen the most sound comes from the end (front) of your barrel and your motor. You can dampen the sound of your motor with a good "low" noise hand grip (one that is not open on the grip bottom aka slits on the bottom of the motor plate even though your hand muffles this a good chunk already), a quality motor/gears/shimjob, a good length "foam" filled suppressor and good compression through and through. That is what I have seen work the best. P*'s benefit from no noise given from a motor so they are 1/2 way there along with the ability to change the amount of air by adjusting your PSI on your rig. So running 60-80 PSI can get you very quiet with a P*.
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Post by Zinger on Apr 29, 2014 20:35:31 GMT -5
I'm really starting to see the appeal of a p*. Not quite sure if I could deal with that hose, but it might be worth it. I have quite a bit to go off of. I'll see how it goes in the next few weeks and perhaps I'll be able to try out some of these suggestions. Thanks for everything guys.
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Post by MayhemXXXFrosty (AndrewMp5k) on Apr 29, 2014 21:34:25 GMT -5
You could always get the Redline AirStock Kit if the air rig doesn't appeal to you. Though obviously you lose the stock option coolness like using a sexy Magpul UBR stock or something. |
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Post by Zinger on Apr 30, 2014 5:57:48 GMT -5
Oh boy that stock thing is ugly... I think I can live with the hose if it means avoiding that thing. I don't think I'd put the UBR on it, while that is probably my favorite stock ever, I think an ACS stock would look a bit better on an SR-25. If this was based off a M4/16 I'd defiantly put a UBR on it.
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Post by Shadow (314) on Apr 30, 2014 13:53:23 GMT -5
I've found that foam filled suppressors can dampen sound a bit but, it more effectively lowers the sound. If you want to actually suppress your sound, a suppressor should have open air pockets with the end walls at the right distance to reflect the sound back to the source in order to cause an interference. This is how a muffler works and how the real steel can make it happen too. Just be aware, this may not be legal without certain permits.
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