I asked this in my other Karlson Pipe thread but nobody picked up on it yet so I post it here as a stand alone question.
How important is a uninterrupted slot? Vibrations in large tubes are a problem and could be greatly reduced if the tube is not completely cut through. Is there anyone with enough understanding of the principals or a way to model it who can indicate if slot interruptions are OK and how big/numerous these interruptions can be before it starts to hurt performance?
Another way to reduce vibration is to use different layers. I have seen people use metal and polypropylene. Here my question is; what effect does the thickness of the tube wall have on performance/sound? I could use rubber or cork sandwiched between layers of fiberglass/epoxy but this will give a thicker wall than most tubes I see.
If the slot portion has to be thin I could construct something like this to drastically reduce flexing/vibrations.:
Just for completeness I copy/paste a reply from GM to my pipe bracing question in my other thread here. Please chime in if you have ideas about this:
Depends on its design BW, i.e. low frequencies are transparent to them, so will begin 'speaking' with harmonics once ~ a WL long, so best to use just one if possible.
For example, a 1st approximation and ignoring any pipe end correction; a 2" dia. pipe x 24" slit will have a ~13543.3/pi/2 = ~2155.5 Hz dia., 13543.3/4/24 = 141.1 Hz slit, so its mean = (2155.5 x 141.1)^0.5 = ~551.4 Hz is where you want to place a brace and fine tune its location from there.
The question I still have is how important is a uninterrupted slot?
Depends on its design BW, i.e. low frequencies are transparent to them, so will begin 'speaking' with harmonics once ~ a WL long, so best to use just one if possible.
For example, a 1st approximation and ignoring any pipe end correction; a 2" dia. pipe x 24" slit will have a ~13543.3/pi/2 = ~2155.5 Hz dia., 13543.3/4/24 = 141.1 Hz slit, so its mean = (2155.5 x 141.1)^0.5 = ~551.4 Hz is where you want to place a brace and fine tune its location from there.
Hi Erik, I think that the use of shorter slots, which mimics one long expanding slot, in the transylvania tubes would be a good idea for reducing tube vibrations. The simple braces I used did show a measurable impact on tube vibrations so the segments of continuous tube between the slots would do the same thing, maybe better. What I don't know if such shorter slots will impact the quality of high frequencies exiting the slot. Although such ideas to reduce tube vibrations will not make any difference with the resonances caused by the discontinuities caused by the edge tube slot.
Retsel
Retsel
You can set the braces at an angle so they don't hit the wavefront head-on. You can also alternate the angle so the zipper effect is partly shifted down an octave.
If they are all spaced evenly, the zipper effect will occur at one frequency (zing). So an exponential spacing (zoing) or irrational spacing (splash) is better.
It strikes me that one solution that meets several criteria is to wrap a spiral of wire around the pipe. It's round and can be smaller than the outer circumferential resonance mode of 20KHz. It will naturally be angled relative to the wavefront, and the spacing can be anything. Insulated wire of various thickness or type can be used to find something optimal, or maybe something like fishing line can be used.
Another option is to cover the whole slot with acoustically transparent fiberglass or some other mesh.
If they are all spaced evenly, the zipper effect will occur at one frequency (zing). So an exponential spacing (zoing) or irrational spacing (splash) is better.
It strikes me that one solution that meets several criteria is to wrap a spiral of wire around the pipe. It's round and can be smaller than the outer circumferential resonance mode of 20KHz. It will naturally be angled relative to the wavefront, and the spacing can be anything. Insulated wire of various thickness or type can be used to find something optimal, or maybe something like fishing line can be used.
Another option is to cover the whole slot with acoustically transparent fiberglass or some other mesh.
I used a series of smaller holes in the iBIBk: https://frugal-phile.com/boxlib/iBIBk-FE12x-map-060307.pdf
dave
dave
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I thought about this. But it will only work in tension, not compression. Unless a more rigid mesh is used. Like expanded metal meshAnother option is to cover the whole slot with acoustically transparent fiberglass or some other mesh.
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