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Clipping?


Lord-of-the-strings
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It is when the peaks of the signal get clipped off - don't go above a certain level.

It usually refers to a means of creating distortion. Clipping can occur in an over driven amplifier stage or by means of diodes across the signal or feedback path in an opamp stage.

Think of a tall mountain with a jagged top representing your clean signal. When you clip the peak you wind up with a "mesa" - a distorted mountain or signal.

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Ah, thank you. So it just means more distortion is created? I was pondering this because I was reading up on the Screamer clone on www.buildyourownclone.com and it said there's one mod you can do to the kit that causes a more clipping sound, so it'd be more overdrive? Or am I still wrong? :D

EDIT: Hang on... so is that why an amp becomes overdriven? Because the amplitude of the sinewave becomes to great and it "clips"? Another question I have, in the diagram, why can the sinewave not go beyond that size without being clipped?

Edited by Lord-of-the-strings
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"When an amplifier is pushed to create a signal with more power than it can support, it will amplify the signal only up to its maximum capacity, at which point the signal will be amplified no further. As the signal simply "cuts" or "clips" at the maximum capacity of the amplifier, the signal is said to be "clipping." The extra signal which is beyond the capability of the amplifier is simply cut off, resulting in a distorted waveform."

http://en.wikipedia.org/wiki/Clipping_%28audio%29

This is where preamps come into the picture. The preamp of a circuit is what (as far as I know) actually allows the signal to be clipped. I.E., the poweramp of the stage determines the maximum amplification of the amp, while the preamp is what drives the signal higher and creates clipping (think setting the master volume at maximum; any increase in the gain knob (preamp volume) will cause clipping to occur).

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hey just thought id add a question of my own here, iv heard tube amps clip asymmetrically, in a standard overdrive/ distortion stompbox you can add an extra diode to make it clip asymmetrically, im curious to which way around this should be placed. in other word the extra diode would be placed in series with that of one of the existing diodes if i were using something like this would i place it in series with the top or bottom diode?

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hey just thought id add a question of my own here, iv heard tube amps clip asymmetrically, in a standard overdrive/ distortion stompbox you can add an extra diode to make it clip asymmetrically, im curious to which way around this should be placed. in other word the extra diode would be placed in series with that of one of the existing diodes if i were using something like this would i place it in series with the top or bottom diode?

Since the ear is not sensitive to phase differences, it wouldn't matter if you placed the other diode in series with either D1 or D2. Just make sure you get it oriented correctly.

Whether a tube amp stage clips symmetrically or asymmetrically is a function of it's bias point. If the bias of a tube stage is set so that the plate voltage is exactly 1/2 that of the supply B+, it will clip symmetrically. Two asymmetrically clipping stages in series will produce symmetrical clipping as a result of their combined action on opposite sides of the signal.

A push-pull output stage will clip symmetrically. So if you're driving your output stage to clipping, it really doesn't matter how the signal was clipped prior.

Despite popular opinion about tubes vs solid-state, the majority of the distortion being produced and recorded is clipped symmetrically (i.e. higher in odd order harmonics).

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Despite popular opinion about tubes vs solid-state, the majority of the distortion being produced and recorded is clipped symmetrically (i.e. higher in odd order harmonics).

There isn't really that much of a difference between tubes and solid state devices when speaking of clipping. The main differences are that tubes clip a little more gracefully, and tubes have a strong 2nd order harmonic in addition to the predominant 3rd order. Couple that with more tubes having a higher harmonic distortion, and people will say that it "sounds warmer". In some respects, solid state is better - especically from a reliability and power usage standpoint. Engineers love to say that when you listen to tubes, you are "hearing the sound of distortion", but I still like the sound of a tube amp the best. Tubes do seem to compress the sound a little bit whilst transistors don't really. Once they reach their clipping point, they can start to sound nasty. But, then again, a lot of great sounding stompboxes use solid state transistors. :D

N.B. One solid state amp that has great sounding distortion is the Lab Series L5. If you've never heard one, check out "Dogman" from King's X - that's Ty Tabor playing thru an L5. Great crunch! Or, Allan Holdsworth around the time of "Metal Fatigue". L5 on that album, too.

Edited by Paul Marossy
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