Measuring output power.

[longislandrod]

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

[Abstract]

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

[Andy Le Blanc]

P=E2/R ac V across a load....... rms

[longislandrod]

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

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

[Andy Le Blanc]

there is a differance between max P and max P before distortion.....