[ultraviolet353]

what is clipping--is it distortion or something else?

 

[Jeff Guidry]

from Car Audio FAQ, written by Mr. Brownstone, Head Honcho. This info deals more with high wattage amps, but you can get the basic idea of how it applies to all audio products, including headphones and headphone amps:

"CLIPPING?

Clipping occurs when an amplifier is requested (by pre amp signal) to produce more output voltage than it has the capability to do so.

EX: A RF 800.2 amp ~1000W @ 4 ohms mono.

What is the Max voltage that amplifier is capable of producing @ 4 ohms?

P = I V where P= power, I= current, V = Voltage

V = I R where R= resistance (impedance)

P= 1000W; R = 4 ohms

P = I * V; since V = IR
P = I^2 R
1000W = I^2 * 4
I^2 = 250
I = 15.81 amps

Since V = I*R
V = 15.81 * 4 = 63.25 volts
__________________________________________________
ENOUGH MATH!!!!!!!!

When the amplifier gets to 63.25 volts output (regardless of 4, 2 or 1 ohm output) that amplifier reaches its maximum voltage. At that point, any request for a higher voltage is just DENIED!!! The amplifier may continue to produce 63.25 volts at one or many frequencies, but that is the maximum output voltage it is capable of.

The amplifier isn't capable of DC output, just that the signal output reaches a maximum ceiling. Diagrams of square waves; whereas, the tops & bottoms of waves being clipped off are accurate for just that. They are not to be interpreted as indicative of amplifier frequency movement. The speaker and amplifier don't discontinue to move because the amp is clipped, only the output does not increase even when you turn up the volume. The strongest frequency is stopped at a maximum, while the other information continues to be amplified.

Keep in mind, any amplifier that is capable of putting out 1000W rms is capable of putting out 2000W max (fully clipped signal). In the above case, where your speaker is capable of handling 1000W rms, it won't survive 2000W continuously, and will melt should you give it 2000W.

The reason most stores and alleged gurus tell you that clipping kills speakers is because most people coincide speaker value and attaining the maximum heat or excursion capabilities of the speakers. That's what the Rane publication shows."

 

[mkmelt]

The audible and measurable results of clipping are harmonic distortion of the signal. This is true for tiny headphone amplifiers as well as for 1000 Watt monster amps. Momentary clipping of a signal, while not a good thing, is not usually audible and will not by itself damage a loudspeaker driver or headphone driver.

Both tube and solid state amplifiers can be made to clip their output signals if driven with too high an input signal. Clipping a solid state amplifier creates odd-order harmonic components that are perceived by the human brain as unpleasant and harsh sounding. Tube amplifers exhibit a slightly different type of clipping, generating even order harmonic components that are less grating on the ear.

Some headphones require very little amplifer power to achieve sound levels that are at least as loud as the typical user might be able to tolerate. These may be powered by almost any headphone output of a portable player or computer sound card.

Less efficient headphones, i.e. the AKG K1000 EarSpeakers, require 10 watts of power per side to be able to be played at realistically loud sound levels. These headphones do not even come wired to headphone plug because the manufacturer expects that the user will connect these headphones directly to the speaker terminals of a power amplifier capable of at least 10 watts of output.

The efficiency of most headphones lie somewhere in between, with the vast majority being able to achieve sufficient output with far less than 1 watt of power. In fact, many headphones can be damaged by being fed with power levels exceding much more than even 1 watt.

If your favorite headphone requires more power than your CD player or MP3 player can provide, and you turn up the volume beyond the output ability of the tiny integrated circuit amplifier chip within the player, the sound you hear will suffer and begin to sound distorted. The only fix is to either use a more efficient pair of headphones, or add a higher powered amplifier between the output of the player and the headphones.

 

[kerelybonto]

Ouch, scary replies, guys.

I assume you're interested in what clipping sounds like, ultraviolet353. As Jeff Guidry and mkmelt said, it occurs when the signal is 'clipped' while being audibly reproduced, usually because of insufficient voltage. So, yes, it's distortion. And it sounds a lot like what you'd expect from its name -- the music will sound like it's missing a layer, what would be the loudest part.

Besides happening as a result of your system, clipping can occur in the recording, usually when something was recorded at too high a volume or when it's mixed to emphasize certain frequencies and they end up being too emphatic -- see my post in the Music forum about RATM's Renegades.

kerelybonto

 

[AssafL]

Clipping is when the amplitude of the output signal is bounded by some maximum value, and attempts to exceed it. E.g. a voltage signal needs to be higher than the "rail" voltage (i.e. the supply voltage). Or a high current drain that cannot be supported by the supply and causes the supply voltage to "dip".

It is purely related to the amplitude of the signal, and is called clipping because the resultant waveforms look as though someone gave them a haircut (e.g. sine waves with their tops flattened).

While clipping is a signal amplitude phenomenon, it does have significant and potentially damaging spectral results.

Quote:

The reason most stores and alleged gurus tell you that clipping kills speakers is because most people coincide speaker value and attaining the maximum heat or excursion capabilities of the speakers. That's what the Rane publication shows."

Clipping DOES kill speaker systems (which use a passive crossover network), not because of the maximum heat or excursion capabilities, but because of the spectral content of the signal.

Clipping causes a "rounded" square wave to be formed, which has harmonics at very high frequency. Unfortunately, the attenuation of these harmonics is very low (and does not exist for true square waves). Tweeters can take between 1%-10% of the total energy supplied to a speaker system (depending on the crossover frequency). A low frequency sine wave that is clipped will have a comb of high power odd harmonics. These harmonics will be routed to the tweeter by the passive crossover, potentially frying the "power shy" tweeter.

Where did the quote come from? For car systems, it is customary to wire individual speakers to individual amplifiers, and using an active crossover. In that case, clipping of a woofer amplifier will affect only the woofer and will not damage the tweeter (which is connected to a separate amplifier).