PDA

View Full Version : Bump...

Nikuk
01-06-2005, 03:23 PM
Lately I've gotten more PM's then usual in regards to tuning.

Here is the formula to be copied into MS Excel:

Fs=0.159*(((Av*(1.84*10^8))/((Vb*1728)*(Lv + 0.823*(Av^0.5))))^0.5)

Fs = Tuning Frequency
Av = Port Area
Vb = Enclosure Volume
Lv = Port Length

You need to make a few reference cells in the spreadsheet (whichever program). You'll need Gross volume, Net volume, Port area, and Port length seperate from this 'cell'.

This formula has been posted many, many times. As a matter of fact, that's how I came across it long ago. It meshes with a 1.5% +/- to BBP6 (when YOU account for port end correction).

Use it if you wish, if not, so be it. This has worked for me for quite sometime.

themainjam
01-06-2005, 03:31 PM
thank you. those people need to use the search button... :(
and heres where you can dload the port calc excel file!!!

http://www.rockymountainfun.com/amp/portcalc.xls

Nikuk
01-07-2005, 10:07 AM
thank you. those people need to use the search button... :(
and heres where you can dload the port calc excel file!!!

http://www.rockymountainfun.com/amp/portcalc.xls

lol... good point.

req
01-07-2005, 10:20 AM
ok, thats all and good, but you need to label what FB\VB\LV are for people who dont know. hell, i havnt memorized it yet. but good job with that excell file.

remember kids, this will ONLY solve your port volume\length\size. it will NOT add the thickness of the MDF as a displacement, and it will NOT create a box-size relative to this port for you.

for instance, if you decide your sub wants 1.0ft^3, and you create a port (using whatever) and the NET PORT DISPLACEMENT (port walls+port+end correction) - for ease sake lets say the net port volume is .3ft^3, your box is now .7ft^3. and you need to correct this by making a box that is 1.3ft^3 and adding the port.

Av is the cross-sectional area of the port (in square inches),
Lv is the length of the port (in inches)
Vb is the enlcosure's net volume (in cubic inches)
Fs is the tuning frequency of the box\port (in hertz).

//edit

lol, i just realized it is on there :p:

just in a different way than i realized. cool :)

Nikuk
01-07-2005, 10:56 AM
//edit

lol, i just realized it is on there :p:

just in a different way than i realized. cool :)

Good Job.... :tomatofa:

As for all the other stuff...

....regards to tuning.

Here is the formula.....

Tuning, nothing else.

themainjam
01-07-2005, 11:04 AM
i dloaded it from someone else i just decided to host it for you guys!

bcarpenterfhl
01-08-2005, 01:25 PM
i've never gotten a straight answer for this, but is the Vb with or without port and sub displacement? is its with, how do we calculate the port displacement?