Calculating Box Rise

[NcHalfrican]

How do you calculate the box rise of an enclosure? Do you just check the speaker terminals with a DMM? While i'm at it...why does box rise occur?

[Torres]

i copied and saved this from a thread a long time ago. i believe it was a post from team nemesis DJ but i dont remember 100%

Correct you need an AC clamp meter and a dmm. You will need to measure the AC voltage output going to each of your subs or if they're bridged just the wires going into the amp. Once you get the AC voltage you will need to find the AC current. You do this by clamping the negative wire going to the set of speakers. I'll give you an example.

You clamp your wire and get 38.6 amps of current

You probe the + & - wires and get 61.7 volts

Next you would take the 61.7 volts and multiply the 38.6 by it to find your MAX power which would be 2381 watts

Next to find out your impedence rise you would divide the voltage 61.7 by the amperage 38.6 which would be 1.59 ohms

So if you were to have a nominal or starting resistance of .5 ohms you would have a rise of 1.09 ohms, but would have an overall reactive load of 1.59 ohms

[Guest]

why would you clamp the - wire? i always thought current flows through the + wire.

edit: saved that bish anyways. if its from DJ its gotta be solid info

[NcHalfrican]

i copied and saved this from a thread a long time ago. i believe it was a post from team nemesis DJ but i dont remember 100%

Good call on the save

Thanks man!

[Decaf]

why would you clamp the - wire? i always thought current flows through the + wire.

edit: saved that bish anyways. if its from DJ its gotta be solid info

facepalm kranny

[Boon]

Facepalm as

If it's not for PURE SPL then ignore box rise. You can't count on it anyway since it's not a constant, it varies depending on the frequency being played.

[Sampsonite]

facepalm kranny

ROFL!

x2 ... facepalm

[dohckiller808]

i just copied this from another post... hope this helps:

Correct you need an AC clamp meter and a dmm. You will need to measure the AC voltage output going to each of your subs or if they're bridged just the wires going into the amp. Once you get the AC voltage you will need to find the AC current. You do this by clamping the negative wire going to the set of speakers. I'll give you an example.

You clamp your wire and get 38.6 amps of current

You probe the + & - wires and get 61.7 volts

Next you would take the 61.7 volts and multiply the 38.6 by it to find your MAX power which would be 2381 watts

Next to find out your impedence rise you would divide the voltage 61.7 by the amperage 38.6 which would be 1.59 ohms

So if you were to have a nominal or starting resistance of .5 ohms you would have a rise of 1.09 ohms, but would have an overall reactive load of 1.59 ohms

[kirill007]

Second facepalm in this thread.

[Guest]

screw you guys im goin home.... lol