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Hello everyone. This has far more questions than answers but I look at it as planting a seed. I'm overloaded with projects right now but I always like to keep look ahead and scout. I had a thought cross my mind and curious if anyone ever tried it and what the results were. I am an engineer, I like to know how things work 馃檪.

First any foremost if you're unfamiliar with the Tesla valve I strongly recommend a quick look on YouTube. Heres an interesting one playing with fire: https://youtu.be/tcV1EYSUQME - the acceleration of the gas is very interesting and I'm wondering how that would also effect the system but I'm getting ahead of myself.

Thought process is there are pros and cons to sealed vs ported subwoofers. By including a system of optimized Tesla valves, I'm wondering if the sub could be a "leaky" sealed but ported subwoofer. Arrange the valve to allow air/sound out while significantly hindering air into the box.

Immediate concerns are woofer extrusion as the axial resistance one way vs another would be drastically different and how this may or may not adversely effect performance.

Next question is sizing the valves. Subs use big ports. A large tesla valve simply wouldn't work in this scenario in my head as the reverse flow would be negatively effected (I would think) but a set of smaller longer ports may work.

Next up, standard port design is complex and I know is dependent on factors such as length and diameter. I don't know enough about it to know where the optimal vs negative impact would take over let alone how this may translate to the effectiveness of the Tesla valve sizing itself. Perhaps a large qty of small valves arranged in the size and shape of a typical port would be a good starting point.

Tesla valve, 2D vs 3D. I imagine a 3D revolved version would be optimal but functionality of allowing the air flow still works in a 2D layout.

I know port velocity is a factor in performance. Again, I simply don't know enough about it but I'm very curious how the acceleration (linking back to the video above) may impact the outcome and whether its ideal or not. The acceleration in the video could be directly related to the gas expansion during ignition though so maybe it's not applicable.

Finally, just shooting from the hip on all this, how sound waves would be impacted due to the more complex path and how the valve return channels would or wouldn't impact the performance. I imagine the geometry of the valve return channel/pathways can be tailored/optimized by changing their own run lengths, widths and angle. Then again, 2D or 3D valve.

That's all for now, just curious if anyone played with this at all and what others thoughts may be.
 

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Hello everyone. This has far more questions than answers but I look at it as planting a seed. I'm overloaded with projects right now but I always like to keep look ahead and scout. I had a thought cross my mind and curious if anyone ever tried it and what the results were. I am an engineer, I like to know how things work 馃檪.

First any foremost if you're unfamiliar with the Tesla valve I strongly recommend a quick look on YouTube. Heres an interesting one playing with fire: https://youtu.be/tcV1EYSUQME - the acceleration of the gas is very interesting and I'm wondering how that would also effect the system but I'm getting ahead of myself.

Thought process is there are pros and cons to sealed vs ported subwoofers. By including a system of optimized Tesla valves, I'm wondering if the sub could be a "leaky" sealed but ported subwoofer. Arrange the valve to allow air/sound out while significantly hindering air into the box.

Immediate concerns are woofer extrusion as the axial resistance one way vs another would be drastically different and how this may or may not adversely effect performance.

Next question is sizing the valves. Subs use big ports. A large tesla valve simply wouldn't work in this scenario in my head as the reverse flow would be negatively effected (I would think) but a set of smaller longer ports may work.

Next up, standard port design is complex and I know is dependent on factors such as length and diameter. I don't know enough about it to know where the optimal vs negative impact would take over let alone how this may translate to the effectiveness of the Tesla valve sizing itself. Perhaps a large qty of small valves arranged in the size and shape of a typical port would be a good starting point.

Tesla valve, 2D vs 3D. I imagine a 3D revolved version would be optimal but functionality of allowing the air flow still works in a 2D layout.

I know port velocity is a factor in performance. Again, I simply don't know enough about it but I'm very curious how the acceleration (linking back to the video above) may impact the outcome and whether its ideal or not. The acceleration in the video could be directly related to the gas expansion during ignition though so maybe it's not applicable.

Finally, just shooting from the hip on all this, how sound waves would be impacted due to the more complex path and how the valve return channels would or wouldn't impact the performance. I imagine the geometry of the valve return channel/pathways can be tailored/optimized by changing their own run lengths, widths and angle. Then again, 2D or 3D valve.

That's all for now, just curious if anyone played with this at all and what others thoughts may be.


Interesting concept, but I believe your concept of how ports work is badly flawed.

I suggest you look into the physics of the heimholtz resonator.

Chris
 

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Discussion Starter #3
Interesting concept, but I believe your concept of how ports work is badly flawed.

I suggest you look into the physics of the heimholtz resonator.

Chris
I have no doubts there. This is not my area but I do love and appreciate great audio encompassing my ears ever since I was a kid who went out and bought his own magnavox boombox WITH CD player from circuit city 馃槀 by 8th grade a 25disc changer, dual cassette deck, and Dolby prologic receiver powering some good sony towers, centers and rears which I still have today and use (not as primary anymore of course).

I will look into it thr heimholtz contraption and let it stew for a while. Open to additional tips from others as well. My plates full but 5-10 minutes here and there over time before I ramp up is how I operate.
 

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So with respect to port flow characteristics, specifically optimizing ports by adding a flare, the problem is that optimizing flare shape for flow for air exiting a port is different than optimizing flare shape for flow entering a port... and for our concerns flow is alternating. If you optimize heavily for one flow direction, it'll be at the expense of the other flow condition and the port simply doesn't work as well as could have been possible.

If you used a variation on the tesla valve for a port, you'd take the scenario I listed above and just make it much worse.

Chris
 

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The higher the air resistance in the port, the worse.
A port loads the back chamber acoustically, which is very different from what you might expect. The driver only behaves similarly to free air motion below the tuning point of the cab.
Rapid acceleration, either positive or negative, and high particle velocity make a port inefficient, which can be countered by using large flares on both port ends or ports so big, that the air speeds are very low to begin with. Efficient ports are not straight, but look more like the inside of a donut and have as little wall friction as possible (area->round, smooth surface). You see ports like this in almost every vented high output PA cab, since space efficiency plays a big role there. You can also reduce unwanted port resonances this way, to some extent (only really relevant if the cab is not a pure subwoofer).

By using the Tesla valve as port, you'll probably create lots of distortion by forcing the driver to react in a non-linear fashion.
And if the vented sub doesn't sound tight to you, you have a bad driver, a bad cab or a combination of both.
 

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I have no doubts there. This is not my area but I do love and appreciate great audio encompassing my ears ever since I was a kid who went out and bought his own magnavox boombox WITH CD player from circuit city 馃槀 by 8th grade a 25disc changer, dual cassette deck, and Dolby prologic receiver powering some good sony towers, centers and rears which I still have today and use (not as primary anymore of course).

I will look into it thr heimholtz contraption and let it stew for a while. Open to additional tips from others as well. My plates full but 5-10 minutes here and there over time before I ramp up is how I operate.


A port is a heimholtz resonator. Using the correct name will provide better reading material for how they work.

To start out with simply, the port only acts as an air leak below tune. Between the driver unloading and the phase reversal, this is why you can鈥檛 get meaningful output below tune.
Above tune, it acts like a sealed enclosure.

Passive radiators would be another good concept to research.

Chris
 

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The air has to get back into the box, otherwise your ported sub with act like a sealed box.
A sealed box that is overly large, complicated and more costly, for moot...

Problem is, it's not even a good sealed box, because it has a leak (the "mostly" one-way valve).
I'd hazard a guess that it would sound bad and perform bad at-best, and at-worst be worse than ported and sealed.

What I'm saying is: You should totally build this thing, I'm dying to know how it would "actually" turn out!
It'll either be super-awesome or super-horrendous, I can't figure out which... :D
 

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Just imagine how many people clicked on that youtube video
 

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This would be awesome if it was 3 inch diameter and on a car getting tested on a dyno lol
 
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