[Everingham.Curtis]

I'm a newbie to DIY audio, and after looking pretty thoroughly through tangentsoft's tutorial on building a Cmoy (which is what im going to be trying to do), I've heard a lot of mention on op-amp "clipping". What exactly does this mean for an op-amp to be clipping?

 

[scytheavatar]

This explains everything. You should know that the op-amp's output is limited by the Vss+ and Vss- voltages you supply to its power pins. If you exceed those limits you'll get either the hard clipping for solid state amps, or the soft clipping for tube amps. The sound produced tend to be not pleasant, since it sounds like what it is, part of the sound spectrum being sucked away.

And you should note that the effects of the soft clipping is less drastic than the effects of the hard clipping, that's why so many people love tube amps, despite their numerous shortcomings.

 

[Jambo]

Just a random tip - it's actually quite difficult to see on a scope if you use a sine wave until it is quite bad, if possible use a triangular wave, then you can see clipping at very early stages.

 

[Everingham.Curtis]

thanks, that chart is very helpful in explaining exactly what i was looking for

 

[tangent]

Quote:

Originally Posted by Jambo /img/forum/go_quote.gif it's actually quite difficult to see on a scope if you use a sine wave until it is quite bad

True. You're already at 1-2% THD by the time you can see it.

A modern DSO or PC-based scope will (or should, anyway) have an FFT mode which make clipping easy to see, if you have control over the power supply voltage. As you lower the voltage, a steady test tone will stay very much unchanged right up until it starts clipping, at which point you'll see harmonics spring up from the noise floor like mushrooms in a rain forest. That's how I did the most recent clipping tests in my op-amp reviews. Much more accurate than listening for clipping or looking at sine waves.