[mrdeadfolx]

In my time here at Head-fi, I've come to identify with most audio-related terms. When I first got here, I didn't know what "rolled off highs" were, had no idea what "soundstage" meant, etc. etc. Now after listening to as much music as I have in that time, I've been able to relate most of these terms with what I'm listening to. The one I still dont get is "clipping". I understand it's supposed to be an artifact of compressed or poorly engineered/mastered music, but I have yet to listen to music and identify it anywhere. Can someone clear this up for me, and maybe provide an example or two? I'd appreciate it.

 

[PiccoloNamek]

http://en.wikipedia.org/wiki/Clipping_(audio)

 

[mrdeadfolx]

There is nothing on that page, except a notification that there is nothing on that page :/

EDIT: Nvm, just had to add the second bracket to the search. So it turns out Ive heard this millions of times, but I've heard people say they have heard it due to the poor quality of some recordings, not overdriving an underpowered amp while listening. Can someone explain this?

 

[monolith]

There are different kinds of clipping.

An amplifier can clip when it's overdriven. I believe that's called hard clipping.

There's also soft clipping, the abundance of which is one of the things that makes badly mastered music sound bad. If you've ever looked at a waveform of a song, the maximum volume on those is 0dbFS (decibels full scale, 0dbFS being the maximum amplitude that the digital system can represent). When the amplitude of the music attempts to rise over full scale it's artificially cut off at that level, which is soft clipping.

To illustrate, here's some random waveform I found online for something. The extremeties of each band represent 0dbFS. The top waveform doesn't clip anywhere. The second one looks like it clips in a few places, but only momentarily. The bottom clips almost all the time.

The effect is difficult to pick up on if you don't know what to listen for, but once you do it sticks out. I'm sure you can find examples on Google or something. I learned what it sounds like by manually editing a file to where it clipped and seeing what it sounded like.

 

[ericj]

Clipping can happen at any active stage of audio reproduction.

You can clip in the mic preamp, in the mixing board, on the recorder, anywhere.

Anywhere that the wave form exceeds the available peak-to-peak output voltage of a device. And this can potentially occur at any point at all.

A lot of new CDs, the audio was badly clipped before it even got pressed, so it will always sound terrible no matter how nice your gear is.

Or you could have a good clean recording and a player that can't swing enough volts on the output for how far you have to turn it up to hear it as loud as you want, and get clipping at that stage.

 

[marvin]

Quote:

Originally Posted by monolith /img/forum/go_quote.gif There are different kinds of clipping. An amplifier can clip when it's overdriven. I believe that's called hard clipping. There's also soft clipping, the abundance of which is one of the things that makes badly mastered music sound bad. If you've ever looked at a waveform of a song, the maximum volume on those is 0dbFS (decibels full scale, 0dbFS being the maximum amplitude that the digital system can represent). When the amplitude of the music attempts to rise over full scale it's artificially cut off at that level, which is soft clipping.

Soft clipping and hard clipping don't have anything to do with what's causing the clipping, just what the resulting waveform looks like. Soft clipping rounds off the edges of the waveform where it clips, where hard clipping retains the sharp edge. See here for a more detailed explanation.

Most tube amps designs soft clip while most solid state amps hard clip. This was a big deal at the advent of solid state amplifier technology, as while they measured much better than tube amps, they still manged to sound terrible in real world usage. It ended up being that most of those issues were down to differences in clipping handling. As power output capabilities then weren't as high as they are now and dynamic range compression usage was lower, amps routinely ran in output power ranges where clipping was unavoidable. In that regime, tube amps sounded much better due to the difference in harmonic content between soft and hard clipping.

Most clipping issues nowadays have to do with music mastering and the drive toward ever higher dB. As monolith noted, jacking the gain up so that the volume exceeds 0 dBFS incurs some form of clipping, whether it's hard or soft clipping depends on the compressors/limiters the sound engineer uses.

 

[Omega]

The links and explanations above are good, but not simple.

Simple explanation: Clipping indicates a waveform has been "clipped" and therefore information has been lost. This information is usually not recoverable, so if you are concerned with the fidelity of audio reproduction, clipping is to be avoided.

 

[tjumper78]

i used to enjoy my ipod with a cheap cmoy amp for my car stereo. turning up the volume too high on the cmoy, i heard clipping noise with every bass beat.
is that clipping?

 

[MD1032]

Quote:

Originally Posted by tjumper78 /img/forum/go_quote.gif i used to enjoy my ipod with a cheap cmoy amp for my car stereo. turning up the volume too high on the cmoy, i heard clipping noise with every bass beat. is that clipping?

Exactly. If clipping is going to occur anywhere, it's going to be where the waveform has the greatest amplitude. It's simple, too much input leads to distorted and clipped output. This is extremely bad for hi-fi audio. It can ruin sound faster than any other problem.

But while we're on the topic...

Distortion is very desirable, I've discovered, for playing amplified harmonica. You want every single component of the assembly to be as overdriven as possible. Use as much volume as possible to get a good response from the mic, use a lower impedance mic, overdrive into your FBX unit(s), use it to overdrive the preamp section of your amp, use the overdrive feature, and then use a smaller amp so the amplifier and output is also overdriven. It's stuff like that that gives your sound an edge because you're changing the waveform slightly in each step.

Did you know that Stevie Ray Vaughan never used the overdrive feature on any of his amps? That's because he turned up everything else so much and played so hard with such thick strings that his actual output sounded like that.