2 x 2" diameter ports = port noise?

[NitroDuck 10+ year member]

Will i get port noise if i use 2 2" diameter ports that are 7in long and tuned to 30hz? Thats the number loudspeaker101.com gave me. These are going in my custom fiber glass box so length is an issue and i know jack about ports.

Click to read more...

 

[NitroDuck 10+ year member]

It depends on power, cone area, cone excursion, and net volume of your enclosure ...
Also, don't use that 101loudspeakers.com port calculator, it gives you a port that is 3-5 Hz below the actually tuning frequency (Meaning, if you think your enclosure is tuned to 30 Hz, it's actually tuned to 33-35 Hz)

Ok lets see...

power 600rms, 10in woofers, 18mm one way excursion, 2cu ft

 

[NitroDuck 10+ year member]

Ok lets see...

power 600rms, 10in woofers, 18mm one way excursion, 2cu ft

 

[NitroDuck 10+ year member]

well i meant 600rms each...so 1200 watts total, my bad.

so i should have 2 ports at least 13 in long?

 

[NitroDuck 10+ year member]

ok, i know i must sound like a total noob but...what?

im just totally confused. usually i catch on to things quickly and all but ports have been giving me the toughest time.

So with two 2" dia. ports they both need to be 36 in long for a 30 hz tuning?

 

[NitroDuck 10+ year member]

...............

 

[NitroDuck 10+ year member]

ooooooooh...now im getting it....

Whenever i heard port area, i was thinking the area that the whole tube took up. i dont have that much area to work with length though. My box is only 7 1/2in deep and 16in back.

Thanks Jmac for putting up with my noobness. Heres my fiberglass box, I AM NOT about to build another one anytime soon. This winter im going to build a huge box in the back of my winter car (trooper) though.

 

[NitroDuck 10+ year member]

yeah i figured that just now looking at winISD

 

[NitroDuck 10+ year member]

Wow, this is going to be tough ...
So that's 2 ft^3 gross volume ? Have you physically measured it out ?

If not, grab a 1 liter container and pour liter after liter into the box until it's full and don't forget count every liter you pour in ...

yes. i used a one gallon container and converted it to sq ft.

 

[NitroDuck 10+ year member]

How wide is your enclosure ?
So we're looking at ...

2 ft^3 gross volume

- 2 x 0.1 ft^3 driver displacement

- port displacement

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or

2.2 ft^3 gross volume

- 2 x 0.1 ft^3 driver displacement

- port displacement

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4 feet on the widest and 3 on the shortest. and its the the first option.

 

[NitroDuck 10+ year member]

I jsut had an idea...lets say my port calls for a 30 inch length and i only have 16in. Could i get elbows to bend the port on the inside of the box?

 

[jbl_marshall21 10+ year member]

Yes ... //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

eh... a smile must cout as 2 characters sweetness.

yea u can put elbows in i got a couple in my box.

 

[NitroDuck 10+ year member]

Hey, im going to get pipe, elbows, and carpet to finally finish my box off. Do i need an FMOD if i run my box unported at 37 hz or if i port my box to 30-32hz. If i need one for either one which frequency cutoff do i get?