Head-Fi.org › Forums › Misc.-Category Forums › Members' Lounge (General Discussion) › Help! Electronics math question
New Posts  All Forums:Forum Nav:

Help! Electronics math question

post #1 of 2
10/11/10 at 11:14am
Thread Starter 

Here is my question. I have no idea how to arrive at an answer. This is what I get for being an English major. Here goes:

 

I'm trying to figure out how much current in milliamps is going through my speaker wire.

 

 

If I am playing my amplifer at 1 watt into an 8 ohm speaker how many milliamps are passing through my speaker wires?

 

and

 

If I am playing my amplifer at 1 watt into an 4 ohm speaker how many milliamps are passing through my speaker wires?

 

Thanks for your help!

 

Oh, its 14 guage wire!


Edited by chadbang - 10/11/10 at 11:16am
Reply
post #2 of 2
10/11/10 at 11:28am

Voltage = Current * Impedance
Power = Voltage * Current
Power = Current * Current * Impedance

Current = sqrt( Power / Impedance )

For 1W through a 8 ohm load, Current ~ 350 mA.

For 1W through a 4 ohm load, Current ~ 500 mA.

 

Keep in mind that calculating current through this method is just an approximation. Speaker impedance can be significantly off from their stated values, and impedance will vary over the frequency range. 14 gauge wire has ~ 2.5 ohms of impedance per thousand feet, so not much point in factoring that in given variations in speaker impedance.


Edited by marvin - 10/11/10 at 11:32am
Reply
New Posts  All Forums:Forum Nav:
  Return Home
Head-Fi.org › Forums › Misc.-Category Forums › Members' Lounge (General Discussion) › Help! Electronics math question