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Port area. what does it affect?


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And this is why I just said screw it and had triticum do my design and he will be doing the build as well when I'm ready.

That being said a lot of people's definition of "music" is a clipped 30 hz sine wave with some 80 IQ knuckle head grunting about committing crimes and his genitals.

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If your port is too long you run into trouble with pipe resonance.

Pipe resonances will produce extra harmonic waves and in extreme conditions it can adversely affect your overall output.

I believe I talked with Triticum about this at one point and I think I said that you don't want your vent length longer then 1/4th the length of the frequency you're tuning to.

am i reading this right? cause i would need a vent 8" long to tune to 32hz.

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No 1/4 the tuned wave is a good reference for the longest you should have a port.

After that you can get resonances, not sure at what point those become bad, but they could also be good for SPL as they cause a spike in output at whatever frequency the resonance is.

I'm not too well versed on them.

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Krakin's Home Dipole Project

http://www.stevemeadedesigns.com/board/topic/186153-krakins-dipole-project-new-reciever-in-rockford-science/#entry2772370

Krakin, are you some sort of mad scientist?

I would have replied earlier, but I was measuring the output of my amp with a yardstick . . .

What you hear is not the air pressure variation in itself

but what has drawn your attention

in the two streams of superimposed air pressure variations at your eardrums

An acoustic event has dimensions of Time, Tone, Loudness and Space

Everyone learns to render the 3-dimensional localization of sound based on the individual shape of their ears,

thus no formula can achieve a definite effect for every listener.

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Port resonance occurs at the 1/2 wavelength distance of the frequency. Depending on who you ask, it can be a problem or no big deal at all. For those that say its a problem, ideally you want the highest frequency you play through your box to be at least one octave below the port resonance frequency. So if you cross your sub over at 80 hz, you want your first port resonance to be above 160 Hz. This means your port should be less than 44" long (the 1/2 wavelength distance of 160 Hz). If you crossed your sub over lower you could get away with a longer port.

Lots of people violate that and don't seem to have problems though.

"Nothing prevents people from knowing the truth more than the belief they already know it."
"Making bass is easy, making music is the hard part."

Builds:

U7qkMTL.jpg  LgPgE9w.jpg  Od2G3u1.jpg  xMyLoO1.jpg  9pAlXUK.jpg

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As far as output, internal port surface area plays a part as well (if i remember correctly), hence why aero ports are way more efficient that a slot/square port... and why the more sides you add to a port (moving towards a circular shape), the more efficient it gets. Something to do with drag or something....

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I don't do builds with ports because I don't like ported enclosures.

My current build is in my sig. When I'm not in school and working 40 hours a week I'll have time for more builds with different enclosures.

Tritium builds a ton of stuff and I'll let him answer that.

Chevy boy, you are correct on that. There is also a way of calculating how much of whatever dimension slot port equates to an efficiency of an aero.

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Krakin's Home Dipole Project

http://www.stevemeadedesigns.com/board/topic/186153-krakins-dipole-project-new-reciever-in-rockford-science/#entry2772370

Krakin, are you some sort of mad scientist?

I would have replied earlier, but I was measuring the output of my amp with a yardstick . . .

What you hear is not the air pressure variation in itself

but what has drawn your attention

in the two streams of superimposed air pressure variations at your eardrums

An acoustic event has dimensions of Time, Tone, Loudness and Space

Everyone learns to render the 3-dimensional localization of sound based on the individual shape of their ears,

thus no formula can achieve a definite effect for every listener.

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no offence...

but builds ive seen both you do, that have all the answers....

well..

do you have any builds ?

and im not trolling... im asking..

That's a fair question. I certainly don't have all the answers and there are plenty who know more than me. I'm just sharing what I've learned.

As far as builds go, I'm pretty limited as far as what I can do for myself, do to the other aspects of my life. I doubt my single E-12 on a 600 watt RF amp that's old enough to vote is going to impress you much. I've built lots of stuff for other people though that is much more interesting. I can give you specifics if you want.

If you have doubts about anything I say just let me know. I'd be happy to tell you the "how and why" of this stuff.

"Nothing prevents people from knowing the truth more than the belief they already know it."
"Making bass is easy, making music is the hard part."

Builds:

U7qkMTL.jpg  LgPgE9w.jpg  Od2G3u1.jpg  xMyLoO1.jpg  9pAlXUK.jpg

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There is no perfect answer Kyle it's just the way it is. It's why the guys chasing tenths have so many builds and designs and ugly boxes. I know we've talked and I know what I think hurts your current scores. But the bad part is to prove it you'd have to rebuild and then a rebuild doesn't mean louder it's a vicious circle. And it's part of the reason I don't meter. If it's loud and it does what I want the number doesn't matter to me because I'd be obsessed on trying to make that number appear.

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