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Hello,
I'd like to share this simple schematic of a very good clipping indicator. Most indicators measure the non amplified signal and take no account of what is happening in the power stage, then the designer "calculates" what should be the clipping level by multiplying the value with the voltage gain of the amplifier. This is not a good way to know if a power amp is really clipping.
For starters, is it a 4 ohm or a 8 ohm load ??
How much is the power supply voltage sag ??
How much is the voltage loss over the transistors/mosfets & output resistors ??
How much parallelled transistors/mosfets does the power amp have ??
All these parameters have an influence on the clipping behaviour af a power amp. (and i left out the frequency ...)
I've seen several complex circuits that might work good enough, but why make it so complicated if it can be that simple.
This very simple circuit is a slightly modified version of a clipping indicator that was used by W. Marshall Leach ... the creator of "The Leach Superamp" (Leach SuperAmp Plans) & for the description (Leach Amp Plans - Part 1) who recently deceased ... RIP (google for it, it's a great article).
It compares the output signal to the power rails and takes the voltage losses of the components into account. I added a switch for 4 ohm & 8 ohm loads and a multiturn trimmer to calibrate the circuit for universal use, used 2 resistors in series to avoid the usage of "big resistors", and i added a transistor to switch the LED with a delay. The big advantage of this indicator is that you can use it from 20V up to 100V rails ... with minor adjustements (zenerdiode).
I even designed a board for it, if any interests, just mail me and i'll gladly send it to you.
Grtz
I'd like to share this simple schematic of a very good clipping indicator. Most indicators measure the non amplified signal and take no account of what is happening in the power stage, then the designer "calculates" what should be the clipping level by multiplying the value with the voltage gain of the amplifier. This is not a good way to know if a power amp is really clipping.
For starters, is it a 4 ohm or a 8 ohm load ??
How much is the power supply voltage sag ??
How much is the voltage loss over the transistors/mosfets & output resistors ??
How much parallelled transistors/mosfets does the power amp have ??
All these parameters have an influence on the clipping behaviour af a power amp. (and i left out the frequency ...)
I've seen several complex circuits that might work good enough, but why make it so complicated if it can be that simple.
This very simple circuit is a slightly modified version of a clipping indicator that was used by W. Marshall Leach ... the creator of "The Leach Superamp" (Leach SuperAmp Plans) & for the description (Leach Amp Plans - Part 1) who recently deceased ... RIP (google for it, it's a great article).
It compares the output signal to the power rails and takes the voltage losses of the components into account. I added a switch for 4 ohm & 8 ohm loads and a multiturn trimmer to calibrate the circuit for universal use, used 2 resistors in series to avoid the usage of "big resistors", and i added a transistor to switch the LED with a delay. The big advantage of this indicator is that you can use it from 20V up to 100V rails ... with minor adjustements (zenerdiode).
I even designed a board for it, if any interests, just mail me and i'll gladly send it to you.
Grtz
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