So this is something I stumbled across completely by accident when playing with an AAA Slayer .308. If you've ever shot one, or seen one shot, it is obvious that they have a distinct and surprisingly loud tube ping. I was working on a mod for it, and stumbled across this completely by accident: the air tube ping actually increases in amplitude over time aka gets louder.
To be clear, I’m only pretty sure of all this, you can never been 100%, but looking at the timeline, other tests, so on and so forth it seems to be the only thing that makes sense. Also this is NOT a factory config, this is an entirely different moderator without which it is impossible to discern the tube ping. So, in the above trace highlighted in yellow, you can clearly see the “uncorking event,” that is to say the moment when the pellet exits the muzzle of the moderator. It is a bit messy here, because it is all mushed into the tube ping….. which clearly increases in amplitude over time. This might, on first blush, sound a little screwy. How, after all, could the tube ping get louder AFTER the most violent event (valve opening/closing)? If you think about it for a minute though, this actually starts to make sense. When the valve first opens, the air/sound in the tube won't be moving in a uniform wave. The air nearest the valve will expand substantially more than the air nearest the gauge. Similarly when the valve first closes, the air won’t all simultaneously stack up at that end of the tube in a pressure spike because it isn’t all going at the same speed. It takes a couple cycles back and forth for that air movement to coalesce into a uniform sound wave front and thereby reach peak amplitude/intensity. Then, obviously, hysteresis naturally damps it back down to zero over time, in this case a much longer time than was sampled. Look at that happen too. Initially the sound is messy, very messy (look at the area between the yellow highlighting and the teal highlighting), and it actually takes a little time for the wave to coalesce around its primary frequencies. As it does so, it increases in amplitude! I was COMPLETELY not expecting this, but now that I've found it, I thought I ought share it.
Maybe I'm about to be told this all is old news and everyone already knows this, but it is not only news to me, it suggests a variety of interesting and novel ways that tube depingers can be made, because you don't have to break up a standing wave, you simply have to stop it from being formed!
Anyway I hope all this was interesting to someone at least.
To be clear, I’m only pretty sure of all this, you can never been 100%, but looking at the timeline, other tests, so on and so forth it seems to be the only thing that makes sense. Also this is NOT a factory config, this is an entirely different moderator without which it is impossible to discern the tube ping. So, in the above trace highlighted in yellow, you can clearly see the “uncorking event,” that is to say the moment when the pellet exits the muzzle of the moderator. It is a bit messy here, because it is all mushed into the tube ping….. which clearly increases in amplitude over time. This might, on first blush, sound a little screwy. How, after all, could the tube ping get louder AFTER the most violent event (valve opening/closing)? If you think about it for a minute though, this actually starts to make sense. When the valve first opens, the air/sound in the tube won't be moving in a uniform wave. The air nearest the valve will expand substantially more than the air nearest the gauge. Similarly when the valve first closes, the air won’t all simultaneously stack up at that end of the tube in a pressure spike because it isn’t all going at the same speed. It takes a couple cycles back and forth for that air movement to coalesce into a uniform sound wave front and thereby reach peak amplitude/intensity. Then, obviously, hysteresis naturally damps it back down to zero over time, in this case a much longer time than was sampled. Look at that happen too. Initially the sound is messy, very messy (look at the area between the yellow highlighting and the teal highlighting), and it actually takes a little time for the wave to coalesce around its primary frequencies. As it does so, it increases in amplitude! I was COMPLETELY not expecting this, but now that I've found it, I thought I ought share it.
Maybe I'm about to be told this all is old news and everyone already knows this, but it is not only news to me, it suggests a variety of interesting and novel ways that tube depingers can be made, because you don't have to break up a standing wave, you simply have to stop it from being formed!
Anyway I hope all this was interesting to someone at least.
