Differentiator help..

[huricaine]

I mean isn't there a difference in percentage between power and voltage distortortion? THD of amps is given in the distortion percentage in power but there is also a calculation in voltage which is what we are discussing with the notch filter.

 

[audioguru]

Distortion is always a level of voltage, not power.
The attenuation of a notch filter also is a measurement of voltage, not power.

The power ratings of most amplifiers are simple lies. "100 Whats of music power at 10% distortion at only one frequency for only a moment (into a short circuit)"!
Instead they should say that the output power at a low distortion (0.1% or less) is 25 Watts into 8 ohms from 20Hz to 20kHz CONTINUOUSLY!

 

[huricaine]

I came up with an idea to detect, and know what % of distortion is detected, it was something I have been thinking about. Since different amps of different sizes will be used, I could use a voltage regulator(buck) that pulls the fundamental comming in, down to a specific voltage(say 3V) and compare it with a refrence voltage that is a fraction to the fundamental(pertaining to the distortion % I want). I have LM2576t adj simple switcher device but i don't know if it works with an AC input, do you know if it does?

 

[audioguru]

A switching buck voltage regulator will not reduce an AC signal, instead it reduces a DC power supply voltage.
An analog compressor/limiter circuit that is fed an attenuated signal of varying levels will produce a fairly steady output level that can be tested for the amount of distortion.

 

[huricaine]

I cannot find anything on google...

 

[audioguru]

I cannot find anything on google...

There are many compressor/limiter circuits in Google. Some of them control program levels or control the level of a sinewave oscillator with a Jfet. The signal is rectified and feeds the gate of the Jfet that reduces the signal level when it is more than a refrerence voltage.