Cone area vs power

[bkolfo4]

X2 can you elaborate on that a little bit? Only thing I could think of where as the length isnt as long it would be less the port has to "control" the sound waves and would affect the louding on the woofer.. But idk

The port is a Helmholtz resonator. It allows "one" frequency to pass - the frequency it is tuned to. The size vs length just changes that frequency.

For a given port area, the only way to have a shorter port for the same tuning frequency is to have a big box. The larger box will gain you efficency. I was wondering if that was what he was trying to say.

[71fordranger]

What kind of amp are you using? The RMS of the subs doesn't matter if the amp is only going to be 1000wrms max. If it is only 1000w rms, having two 12's that are requiring 1000 each would be way underpowered. I heard FI can eat power like a mofo, so I'd even send a little over rms.

As far as which gets lower, you really can't say. I have a 12" that sounds absolutely amazing and hits the lows that I can't even hear on my 15". It's all about enclosure design. People have hit in the 150's with 8 15's.... And then there's others that have the same numbers with a single 18". I don't know if I missed it, but I didn't see if you specified whether you want it to be loud as hell, or if you want it to sound musically eargasmic.

As for wow factor, yes, an 18" is more.... exotic you could say... But if you're skilled enough, you can make an enclosure for 2 12's look super clean, and really nice.

Right now I got a Phoenix Gold 1200.1 Tantrum but will b upgraded later

[71fordranger]

I googled it and got this

http://www.mechmanhighoutputalternators.com/shop/products/270-Amp-Chrysler-Dodge-Alternator.html

Looked again and seem I had the wrong link, yours should be this one

http://www.mechmanhighoutputalternators.com/shop/products/270a-High-Output-Densto-Style-Dodge%7B47%7DChrysler.html

FML, I've been lookin off and on 4 a year now and couldn't find one and in ten minuets u find 1. :/

Yea that's it but that will have 2 wait till summer if I wanna get that. That's kinda my whole budget in one alt.

[99fullsizechevy]

For 2kw just get a nice xs battery up front and one in back and you will be fine for the time being.

[99fullsizechevy]

X2 can you elaborate on that a little bit? Only thing I could think of where as the length isnt as long it would be less the port has to "control" the sound waves and would affect the louding on the woofer.. But idk

The port is a Helmholtz resonator. It allows "one" frequency to pass - the frequency it is tuned to. The size vs length just changes that frequency.

For a given port area, the only way to have a shorter port for the same tuning frequency is to have a big box. The larger box will gain you efficency. I was wondering if that was what he was trying to say.

That's sorta what I was trying to get out, but my thought process is a little altered ATM and I could get out what I wanted to put.. Makes alot more since how you said it tho..

[412 CVX]

Just thought i'd explain my theory on the shorter port.

pretty simple really. here's an analogy.

if you had to run 100 meters to get to the gas station, you could (probably) do that pretty easy. Now say you had a choice between running that 100 meters to the gas station, or having to run a mile and a half to the gas station; which would be easier and more efficient?

same thing (sort of) applies to the port length. the longer the air has to travel and the more turns and corners it has to take, the slower it exits because of the increased turbulence.

that's one reason why flared aeroports are so efficient. the air doesn't have to travel very far, it travels in a straight line, and entry and exit are very streamlined. the flares reduce turbulence.

[SnowDrifter]

X2 can you elaborate on that a little bit? Only thing I could think of where as the length isnt as long it would be less the port has to "control" the sound waves and would affect the louding on the woofer.. But idk

The port is a Helmholtz resonator. It allows "one" frequency to pass - the frequency it is tuned to. The size vs length just changes that frequency.

For a given port area, the only way to have a shorter port for the same tuning frequency is to have a big box. The larger box will gain you efficency. I was wondering if that was what he was trying to say.

What I was getting at is that the 12s, although they would have less cone area, would be running double the power of the 18 (assuming I read OP's post right). So the 18 wouldn't need much more port (if any) than the 12s.

Similar sized ports in a box that is 2 cubic feet larger means a shorter port for the same tuning point. The way I understand it is that having a shorter port means there is less internal surface area of the port walls for the air to rub against -> less friction -> greater port velocity -> higher output (kind of why people paint their boxes and ports in fiberglass resin - to make it smoother)

Not sure how noticeable this would be to the ear though

Edit: 412 CVX just took the words right out of my mouth

[stroupe79]

That theory goes completely against Tlines...so does that mean Tlines are less efficient?..just wondering

[99fullsizechevy]

That theory goes completely against Tlines...so does that mean Tlines are less efficient?..just wondering

Good question..

[fritosaregood]

X2 can you elaborate on that a little bit? Only thing I could think of where as the length isnt as long it would be less the port has to "control" the sound waves and would affect the louding on the woofer.. But idk

The port is a Helmholtz resonator. It allows "one" frequency to pass - the frequency it is tuned to. The size vs length just changes that frequency.

For a given port area, the only way to have a shorter port for the same tuning frequency is to have a big box. The larger box will gain you efficency. I was wondering if that was what he was trying to say.

If you go into the fluid dynamics side of it, a longer port may require a bend or more bends, and each bend will create a loss in the system. Also a longer port will have more time the air moving in and out will be in contact with the port, creating more friction inside the port which also creates a loss. I usually don't care for how long a port is when I build a box, except for trying to get the least amount of bends, or none at all.