PDA

View Full Version : L-port = Slot port?



Casper80
11-21-2006, 03:12 AM
are these 2 the same thing?

also the width between 1.5" and 3" if adjust to the same tuning frequency and box ft3 they will sound the same right?

example like i use the calculator and draw up a L port with 1.5" [email protected]

and another design is L port with 3" [email protected], they both will have the same sound right?

other than the size and weight difference of the 2 box and let's say both are properly brace and built which 1 is better than other?

is ported noise an issue on either 1.5" or 3" port? or the different witdh will affect the soundpressure output of the sub?

thanks.

geowick07
11-21-2006, 03:37 AM
From the Detroit area here! :wave: Welcome!

the size of your enclosure, at least in the way you are describing, doesn't really come into play for the tuning. The port length and width (read: port area) are the only dimensions that affect tuning.
So, to answer your first Q, no, they won't sound the same. The only way they could sound the same is if you changed the length to allow for the difference in width.
Second Q, neither is really "better" because they are two different enclosures.
Third Q, port noise depends on the way you finish your ports, and how they are designed. Read up (read: search) to learn more about this.
Any Q's, search first, and if you cannot find the answer, feel free to ask away. But, to cover your own @ss, be sure to search like crazy before posting a new thread, such as this one. Most, but not all, questions of this nature, can be found without staring a brand-new thread!

Volenti
11-21-2006, 03:42 AM
An L port is a slot port with a bend in it.

At low signal levels they will both sound the same (assuming the lengths are correct for the tuning frequency), however the larger width port will have a lower airspeed and will have lower distortion at high levels.

Casper80
11-21-2006, 03:53 AM
An L port is a slot port with a bend in it.

At low signal levels they will both sound the same (assuming the lengths are correct for the tuning frequency), however the larger width port will have a lower airspeed and will have lower distortion at high levels.

almost got what i wanted, forgot the obvious part.

1.5" [email protected] tuned to 28hz

3.0" [email protected] tuned to 28 hz

both sound the same if i'm reading you right?

and then the larger withd will have lower airspeed and that's mean if i'm at full tilt, the bass sound will be a lot cleaner than the one with 1.5" witdt right?

with a same amp and sub in between these 2 box they will having equal spl level and sq level other than 3" ported will have cleaner sound at full tilt right compare to 1.5 right?

Volenti
11-22-2006, 06:45 AM
They'll sound the same (or very similar at least) up to a certain point, after that the smaller port's airflow will become more and more turbulent and it's output will start to compress, ie; it will stop getting louder while the larger one will keep on truckin'.

This is the reason the spl guys use huge ports.

If you have enough power and sub X-max to exceed the airspeed of the smaller port you should use the larger one, it will be louder (in this case)

Casper80
11-22-2006, 03:06 PM
it'll be for 1000watts rms and i'll be ok to go with the 3" wide port right?


thanks.

PV Audio
11-23-2006, 12:52 AM
It depends. Port area is dependent on two things just as any rectangular area is. It requires to know the port width AND the internal height of the port. Without knowing both, it's absolutely impossible to know what to tell you. Now unless I'm just an idiot as usual, I didn't see you mention that anywhere. Tell us the port height and then, and only then, can we suggest what's best for you.

Casper80
11-23-2006, 01:46 AM
the port withd i got here one is 12.5" height 2" wide, another is 12.5" height and 3" wide.

Lakota
11-23-2006, 03:19 AM
Round ports could be L shapped, if they have an elbow. Port size is not power dependent, it's best determined by box size and subs.

Volenti
11-23-2006, 04:10 AM
Round ports could be L shapped, if they have an elbow. Port size is not power dependent, it's best determined by box size and subs.

Power is most definitely something you need to factor in the choice of port size (port area, not tuning frequency)

The more power you apply-the more the sub moves-the more air that must flow through the port.

Casper80
11-23-2006, 01:57 PM
http://www.subwoofertools.com/forum/ported-box.asp?Ew=32&Eh=14&Dia=6&Xmax=22&Vd=.194&NumW=1&Vb=2.2&Fb=28&Qts=&Vas=&Fs=&CE=0

http://www.subwoofertools.com/forum/ported-box.asp?Ew=32&Eh=13&Dia=6&Xmax=22&Vd=.194&NumW=1&Vb=2.3&Fb=30&Qts=&Vas=&Fs=&CE=0

which of these will yield a better result?

PV Audio
11-23-2006, 09:42 PM
Round ports could be L shapped, if they have an elbow. Port size is not power dependent, it's best determined by box size and subs.

Not true at all. Vd is determined by the surface area multiplied by the xmax of the speaker. The greater the Vd, the more port area you need. Conversely, the more xmax, the more Vd. To get the speaker to move in the first place, you need input power. Thus, port area is at least 1/4 dependent (although indirectly) on input power.

PV Audio
11-23-2006, 09:43 PM
Power is most definitely something you need to factor in the choice of port size (port area, not tuning frequency)

The more power you apply-the more the sub moves-the more air that must flow through the port.
^^ What he said :emb:

PV Audio
11-23-2006, 09:44 PM
http://www.subwoofertools.com/forum/ported-box.asp?Ew=32&Eh=14&Dia=6&Xmax=22&Vd=.194&NumW=1&Vb=2.2&Fb=28&Qts=&Vas=&Fs=&CE=0

http://www.subwoofertools.com/forum/ported-box.asp?Ew=32&Eh=13&Dia=6&Xmax=22&Vd=.194&NumW=1&Vb=2.3&Fb=30&Qts=&Vas=&Fs=&CE=0

which of these will yield a better result?

Theoretically, they should be nearly the same, however, the labyrinth port design will have more turbulence. Will you notice it? No, most likely not. However, it will be higher than the single bend port.

Chevyaudio
11-23-2006, 09:45 PM
Ported>vented

/thread

PV Audio
11-23-2006, 09:47 PM
Ported>vented

/thread
Were you around for the Below30 debates on the topic? Those were the days :laugh:

Chevyaudio
11-23-2006, 09:48 PM
indeed