tuning a box?

[iamamp3pimp 5,000+ posts]

i agree.

thats way too higm imo

 

[photocrazy8 10+ year member]

35hz is my favorite for any sub of a 12 and bigger //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[pitbull12888]

ok then

so a 23"x 14"x 9.25" is tuned for 43 hz wut size u think i need to go to 35?

 

[Tiger Bass 5,000+ posts]

35-38hz would be ideal

 

[Snozzer 10+ year member]

what about 8" assassins? I got 4 of them. The site says 40 hz but i was thinking thats high. So are these subs good at 35? or should i keep it at the recomended 40?

 

[pitbull12888]

yea that sounds big for 8's... i think the sites just recommend the boxes bigger so the subs are safer from blowing???

 

[acold7dusta 10+ year member]

actually its the opposite, the bigger the box, the less wattage you need to power them, and theres less resistance on the woofer, too low can acctually do damage if it heats up too much

 

[itzme218 10+ year member]

I wouldn't recommend crunching numbers by hand as it is not always very accurate.
Download win isd from this site:

http://www.linearteam.dk/default.aspx?pageid=forums

From there, you can calculate your port length based on tuning frequency and box volume.

There are three main variables when discussing the tuning frequency of an enclosure:

1) Port Area (Av)- This is the opening or cross sectional area of the port. This area needs to be maintained through the length of the port.

2) Port Length (Lv)- This is how far into the enclosure that the port extends. This is found by measuring down the center of the port.

3) Box Net Volume (Vb)- This is the volume of the enclosure minus all bracing, sub displacement, and port volume (port volume is equal to Av*Lv).

Here is the basic relationship between the three variables and do note that their relationships are not linear.

1) Increasing Port area and keeping Vb and Lv constant increases the tuning frequeny (Fb). Decreasing port area and keeping the others constant will decrease Fb.

2) Increasing Port Length and keeping Vb and Av constant will decrease Fb. Decreasing Port length will decrease Fb.

3) Increasing Box Volume while keeping Av and Lv constant will decrease Fb. Decreasing box volume will decrease Fb.

The problem with calculating this using a basic formula is that with different cross sectional area, you will have different surface area on the port walls even though the cross sectional area is equal. For instance, a really tall and skinny rectangular port, that shares the same cross sectional area as a round port, will have more area inside of the port than the round port will have. The rectangular port will also have corners that can restrict air flow in the port. These two factors will change your actual tuning frequency but when calculating them, they will have the same port area and thus the same lengths given a constant enclosure volume.

Winisd takes this into account and will adjust your port length accordingly thus making things much more accurate and closer to what you really want.

Am I reading that wrong or is there something wrong there?

 

[Immacomputer 10+ year member]

Oh shit, good catch. All the decreasing and increasing got to my mind. I proof read it but didn't catch it. Thanks!

 

[iamamp3pimp 5,000+ posts]

i was gonna say it looked fine to me.

then i read the quote.