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Message: <blockquote data-quote="gckless" data-source="post: 8245657" data-attributes="member: 635756">How do I tune a PR?PRs are tuned by adding and subtracting weight, same as with a regular port, only now we are adding physical weights instead of increasing the mass of the air in the port. If that doesn’t make sense to you, think about this: when you tune a regular ported box, you are simply adjusting the weight of the air in the port. Let’s say you want to tune to a certain frequency, 30Hz in this example. Let’s say you figured out your required length of the port to be 25”. In order to tune lower, keeping everything else the same, you are going to have to increase the length of that port. By increasing length, you are adding more port volume, and as a result, more weight of air inside the port. Same goes for tuning higher; less port length, less air mass.Understanding this, I will explain two ways to tune a PR. One is extremely easy, the other is a bit longer and technical. The latter first:To do the math, first you will need to figure out your required standard port length for the given surface area of your “port”. To get this, it’s probably best to use a program/calculator (I like WinISD) and plug in your box size, “port” size and amount, and desired tuning. You will get a length. Then you will need to find port volume, which will be port surface area times port lenth, or (Pi x R2) x L (if you already have surface area, it’s just Sd x L). After you find port volume, you will need port mass, which is Port volume times the density of air (which is 1.225kg/m3).Example (I made up these two numbers for the example, this is inaccurate):15” PR Sd = 830cm2 = 128.65in2Required port length = 55inPort Volume = Sd x L= 128.65in2 x 55in= 7075.75in3 = 4.1ft3 = .116m3Mass = Port Volume x Density of Air= .116m3 x 1.225kg/m3= .1421kg = 142.1gSo, you would need to add 142.1g of weight to the PR to find the given tuning.Here’s another way:Now for the simpler method:Put the things in, do a resonance test with tones, and adjust from there. Your PR’s, just like the air in a port, are going to moving the most at tuning. Also at tuning, and also just like a regular ported enclosure, your powered drivers are going to be moving the least. This is do to resonances affecting internal pressure.So anyway, once you do that, if you want to tune lower, add weight. If you want to tune higher, remove weight.Here is a quick, basically non-instructional (lol) video I made a little while ago:[MEDIA=youtube]QKYn6e1QIb8[/MEDIA] This is all I have for now. If you would like something added, or see something that needs correction, please let me know.</blockquote>

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