Interesting about ports...

[flakko 1]

hmm i got some info today about ported boxes. I was thinking about using a ported box and porting the bass into my cabin. Well... it turns out all the port itself does is boost and PLAY the frequency it is tuned to, and the majority of the bass still comes from the front wave of the sub.

so if i tune the box to 31 hz and i stick the ports into the cabin into the cabin i will hear boom boom boom BOOM boom BOOM the "BOOM" being the frequency the port is tuned to and it will overwhelm rest of the bass.

i think thats why spl people like to upfire the ports into the cabin.

any comments?

[Supa_c 1]

no...

[flakko 1]

the port DOES boost the frequency range its tuned to.

[djjdnap 78]

what?

It doesn't boost it.

Thats like saying if you turn your ssf to 30hz it will boost that freq.

Its not that it boost it, it kinda just plays those freq, better.

Dammit you know what i'm tryin to say.

If you run your car at 100mph it wont like it but will go that fast, if you tune your box to 100hz it wont like it but will still play.

If that all made since

[Acidburn 10]

If that all made since

nope, not really

[djjdnap 78]

GOOOOD

[flakko 1]

yea as in boost i mean play better same difference. cuz in a graph, you see that the line does peak at or around the ported frequency.

[EFFENDI 0]

The ported enclosure system is characterised by lower distortion and higher power handling in the system's operating range, and lower cutoff frequency than a sealed enclosure system using the same driver. Distortion rapidly increases below the cutoff frequency however as the driver becomes unloaded, and the transient response of a ported enclosure system is usually inferior to that of a sealed enclosure system using the same driver.

However, this is not the case for every application. Generally though, ported enclosures typically have more of a "boom" than "bump" sound.

[djjdnap 78]

i thought ported boxes had less power handling than sealed???

Yea, i'm right, shut up, lol, j/k

[mrray13 30]

a ported box only has lower power handling below tuning freq as the amp will lose the ability to control the sub as it and the box unloads. hence all the great pr0n at 25hz in a 35hz tuned box. and because ported boxes tend to be bigger then sealed,otherwise...

a ported box actually has greater inside air pressure then a sealed box due to the port allowing air to be pulled in as the sub moves out.

now, that is in my language..lol....there are other properties that determine why what i said is true(or at least mostly..lol), but i'll let the techie guys explain it...

as to flakko's question...in most cases, a ported box peaks higher then it's tuning, usually around 8-11 cycles, depending upon port area, vehicle, placement...yada,yada,yada. u could easily port into ur cabin and be more then happy. IMO and IME, u won't get the "boom,boom,BOOM" that u think u'll get due to the tuning freq. it'll sound the same as if the sub was there...

wheeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee

[Nikuk 1]

L

O

L

[CBFryman 2]

meh....

thermal powerhandleing never changes, however mechanical does. above tuneing (especially near it) mechanical poerhandleing is greater. this is due tothe fact that hte air in the port has mass and hte speaker has to move it causing more resistance. below tuning (as already stated) the sub unloads and mechanical powerhandleing is decresed because it moves a LOT further.

a port does nothing more than put backwaves from the speaker back to the front with a delay to keep them in phase. its "tuning" is simply a result of the mass of the air's resonant frequincy in relation to the volume of the enclsoure inside.

its kinda hard to explain why there is a bump in SPL around tuning, so think of it this way.

while playing the trombone to change the pitch you change the lendgth of the "port" which you are making your "buhhhhhhhhhhhhhhhhhhhhhh" sound through. the longer you make your "port" the louder the frequincy that makes up a small portion of that "buhhhhhh" gets due to the acoustical properties of the "prort" as you shorten it the same happens with a higher frequncy.

however with a low enought tuning and the right ammount of volume ported responce and be nearly as flat as sealed with a Qtc of 0.707 but with an even mroe extended responce. this usually requires a large enclosure with a port tuned quite low.

in car you dont need much below 28-30Hz because music doesnt get that low. so that is usually where most tune to with the biggest enclsorue they can spare for the flattest responce possible.

in stupid,

the air dun like 2 move. so ahen dat air reacts 2 the air in the box. it wants to move least @ a certian moves per secund. this be teh tuning. it be boosted cus the speaker may still have duh movement to keep movin.

[mrray13 30]

L

O

L

elaborate please....

other then laughing out loud...

come'on, share the knowledge...

wheeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee

[flakko 1]

hes laughin at me cuz of my ignorance

[Nikuk 1]

hes laughin at me cuz of my ignorance

<{POST_SNAPBACK}>

Sorry, I didn't mean to laugh AT You, persay. This is just like 101 stuff that I assumed You knew.

thermal powerhandleing never changes, however mechanical does. above tuneing (especially near it) mechanical poerhandleing is greater. this is due tothe fact that hte air in the port has mass and hte speaker has to move it causing more resistance. below tuning (as already stated) the sub unloads and mechanical powerhandleing is decresed because it moves a LOT further.

<{POST_SNAPBACK}>

You're right on the group delay portion... but thermal handeling does not change? Well, for the coils it doesnt change... however the coils can EASILY overheat with relation to tuning & excursion.

cone speed is greatest @ tuning, therefore the motor's cooling abilities are at their respective peak. as You get away from tuning, You loose cooling efficiency.

Now when You get into grossly over or underdamped enclosures, away from tuning, with actual rated current supplied to the motor is when You have to worry about mechanical limits. You'd most likely have to make a concious effort to reach xsus in "an average" install.

Most of the popular woofers out now have motor designs that, by nature, limit power input in the lower harmonics.

-Nick

[Impious 1,476]

Read up on Helmholtz resonantors.

[Nikuk 1]

OMG I havent heard anyone mention the proper name in a looong time. Prolly not since I stopped crusing diyaudio.. LoL

[Impious 1,476]

Reason it stuck (and reason I mention it) is because it actually helped me better understand what was actually happening in a ported enclosure Everybody always talked about response of a ported box, how to calculate port length and whatnot.......but nobody ever really explained how a ported enclosure actually worked. After I read up on helmholtz resonantors and how they worked, ported boxes just made more sense.......LOL. Kinda like everything fell together for me........

[ANeonRider 3]

Helmholtz... also some of that theory is the basis of intake/manifold design.

[Below 30 0]

One thing is for sure, The "booming" sound is a result of the way the track is produced. That is the "808" bass generally, so no matter if it's ported of sealed, you will hear it.

If your listening to polka music with a bandpass encloser for example, will not hear any booming sound, because polka music doesn't use "808" kits in it's production. The fact is though, that the "808" sounds a little more pronounced in ported, because of power efficiency at the typical tuning ranges. In a sealed, you need to feed alot more power to hear it as well, at given decible level.

If you read a graphic EQ display while playing "808" heavy tracks, you will see the most energy in the 40 to 60 hertz range. The overpowering of the "boom" sound is more a result of not setting the sub amp and mid-bass amp properly. The sub amp's gains should be lowered, to gain a better balance to the mids.

Basically, a speaker and box are not going to create sounds to a music track, that are not there. Unless it's a rattling, as a result of equipment failure.

[Impious 1,476]

Helmholtz... also some of that theory is the basis of intake/manifold design.

Mufflers/exhaust aswell

[ANeonRider 3]

Of course

[LB audio 0]

The closed boxes have roll off 12db/oct, ported box have roll-off 24 dB/oct - output from port shifts 180 deg. below tuning freq. - that' why closed box plays lower than Ported box. Driver in ported box have same thermal limit, but X-max at tuning freq is much smaller then in closed box - that's why it takes more power and it is louder at tuning freq and higher. Due phase shift driver below tuning freq becomes unloaded - you have to use subsonic filter to avoid mechanical demage on driver.

[ngsm13 1]

One thing is for sure, The "booming" sound is a result of the way the track is produced. That is the "808" bass generally, so no matter if it's ported of sealed, you will hear it.

If your listening to polka music with a bandpass encloser for example, will not hear any booming sound, because polka music doesn't use "808" kits in it's production. The fact is though, that the "808" sounds a little more pronounced in ported, because of power efficiency at the typical tuning ranges. In a sealed, you need to feed alot more power to hear it as well, at given decible level.

If you read a graphic EQ display while playing "808" heavy tracks, you will see the most energy in the 40 to 60 hertz range. The overpowering of the "boom" sound is more a result of not setting the sub amp and mid-bass amp properly. The sub amp's gains should be lowered, to gain a better balance to the mids.

Basically, a speaker and box are not going to create sounds to a music track, that are not there. Unless it's a rattling, as a result of equipment failure.

<{POST_SNAPBACK}>

Lol...Below 30 is back....

NG

[Supa_c 1]

Not really, he just randomly posts...and i mean randomly