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Hugh G. Rection

understanding ports, a lesson in dimensions vs efficiency.

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excellent read guys!!

Thank you much for taking the time to write all of the information in this post!!

seen as i do have some port alterations to my existing box, i am really starting to wonder if i wouldnt just be better off to start all over from scratch.

That's exactly what I'm thinking about... Ripping old box out and redesigning/build new aero port box. I thought I could possibly get away with a 6" aero, but it doesn't sound like it now. Looks like an 8" for me... Good write up guys, I hope this keeps moving along. Learning some things here.


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How would you even determine port length with 2 different sized ports?

You would make them both the same length and that length would be determined by the total port area between the two.


"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."

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That's what I was thinking.

see when I start building boxes for my subs I'm going to do a few different aero port ranging from 2-3 6" ports and 1 with a 10" port. Still working on an idea with 2 8" ports. The 6" ports will because its what the manufacturer suggested for round ports just to see how their suggestion works out.

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t1500bdcp

2 t2d4 15"

1 t600.4

1 t400.2

1 set p1 tweets

singer alt, tons of wiring, smd vm-1, 80prs, back seat delete, still in the works, aiming for a 145-147 with the ability to play 25hz up to 50hz.

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I can only think of negatives when considering multiple sized ports.


b_350_20_692108_381007_FFFFFF_000000.png

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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I can only think of negatives when considering multiple sized ports.

Don't be a negative Nancy :-P

Seriously though, what are your concerns?


"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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i cant really understand why someone would purposely get aero ports, just so they could use less port area. aero ports are just crazy efficient, and purposely using them just to go with less port area seems like you are completely defeating the entire purpose of them. spend lots of money on a nice port, and completely defeat its purpose.


Owner of BigAss Ports

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I can only think of negatives when considering multiple sized ports.

Don't be a negative Nancy :-P

Seriously though, what are your concerns?

Resonances.

Would you not have to separate resonances based off of the two areas of the ports?

HelmholtzResonance_zpsbcb61ecf.gif

And then you get the harmonics of the ports getting worse and worse over every next f1*x?

Or would you just use this formula instead to find the resonance of the ports?

f1= velocity of sound divided by two times the length of the column?

With the area having no affect on the second (and third possibly) resonance of the ports?

Now for a tip I read a long time ago from some JBL papers. If you are going to be using a system where you are trying to get every last amp through those coils, you need design your system around the parameters of your speaker when it is hot not when it is cold, as the parameters are going to drastically change from this variable.

Then after you get a hot coil what does it do to the inside of the enclosure? That's right! It gets hot as well, which means you need to go about tuning based off of the temperature of the internal volume of the cavity. As the temperature of air changes the speed in which sound travels through it changes, to find this you need to use this formula.

SpeedofSoundinGases_zpsad1f56a2.png

For air, the average molecular mass for dry air is 28.95 gm/mol, and the adiabatic constant γ = 1.4.

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b_350_20_692108_381007_FFFFFF_000000.png

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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i cant really understand why someone would purposely get aero ports, just so they could use less port area. aero ports are just crazy efficient, and purposely using them just to go with less port area seems like you are completely defeating the entire purpose of them. spend lots of money on a nice port, and completely defeat its purpose.

I suppose people do this because they want to try to make stuff fit into the smallest space possible. I get your point, it just seems like a lot of folks don't have maximum performance as their top priority.


"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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i cant really understand why someone would purposely get aero ports, just so they could use less port area. aero ports are just crazy efficient, and purposely using them just to go with less port area seems like you are completely defeating the entire purpose of them. spend lots of money on a nice port, and completely defeat its purpose.

this is something I understand. I was just simply asking because I once believed the aeroports can be smaller thing but found out that even though it can be smaller doesn't mean it should be smaller.


t1500bdcp

2 t2d4 15"

1 t600.4

1 t400.2

1 set p1 tweets

singer alt, tons of wiring, smd vm-1, 80prs, back seat delete, still in the works, aiming for a 145-147 with the ability to play 25hz up to 50hz.

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