Here's how I measure output power and I'm wondering if there's different schools of thought.
I measure my amp's output at the load with my scope. I crank up the volume just until the output distorts then back off until it's undistorted.
Measure peak-peak voltage, divide by 2, take RMS value multiply by .707, square that value and divide by speaker load (P=V2/R).
Incidentally my input is a 1 khz sine wave about 5-10 mV.
Agreed?
FYI - I just built my first amp albeit from a kit buy I'm going to use it as my building Guinea pig.
Rod
Measuring output power.
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- longislandrod
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Measuring output power.
Last edited by longislandrod on Mon Oct 27, 2008 4:05 pm, edited 2 times in total.
Re: Measuring output power.
longislandrod wrote:Here's how I measure output power and I'm wondering if there's different schools of thought.
I measure my amp's output at the load with my scope. I crank up the volume just until the output distorts then back off until it's undistorted.
Measure peak-peak voltage, divide by 2, take RMS value then multiply by .707, square and divide by speaker load.
Incidentally my input is a 1 khz square wave about 5-10 mV.
Agreed?
FYI - I just built my first amp albeit from a kit buy I'm going to use it as my building Guinea pig.
Rod
Just curious...how do you know if a square wave is clipping?
I'd think a sine wave would work better....but that's just me thinking...I don't get paid to think. lol
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- longislandrod
- Posts: 19
- Joined: Sun Nov 11, 2007 3:15 pm
- Location: New York
Re: Measuring output power.
DUH!!!
I must went brain dead while typing. I meant sine wave, not square wave. I fixed my original post.
Thanks for caching that one....
Rod
I must went brain dead while typing. I meant sine wave, not square wave. I fixed my original post.
Thanks for caching that one....
Rod
Abstract wrote:longislandrod wrote:Here's how I measure output power and I'm wondering if there's different schools of thought.
I measure my amp's output at the load with my scope. I crank up the volume just until the output distorts then back off until it's undistorted.
Measure peak-peak voltage, divide by 2, take RMS value then multiply by .707, square and divide by speaker load.
Incidentally my input is a 1 khz square wave about 5-10 mV.
Agreed?
FYI - I just built my first amp albeit from a kit buy I'm going to use it as my building Guinea pig.
Rod
Just curious...how do you know if a square wave is clipping?
I'd think a sine wave would work better....but that's just me thinking...I don't get paid to think. lol
-
- Posts: 2582
- Joined: Sat Dec 22, 2007 1:16 am
- Location: central Maine
Re: Measuring output power.
there is a differance between max P and max P before distortion.....
lazymaryamps