Got Distortion?

[maxg]

Dean,

I'm interested in your impressions of the USD180 (did I spell that correctly?). By the numbers that one should be hard to beat.

Leo

Leo,

I am not Dean but I did build a kit based on those boards. Frankly - it was dreadful sounding - I was supposed to write a review for the supplier but in the end we both agreed it was probably not a good idea. Course he will probably tell you it is my appalling skills as an amp assember that were at fault - he might even be right - but it was not good.

The bass was out of control, there was a hole in the mids and the whole thing sounded like a radio rather than an audiophile grade amp.

Just my experience of course - which dont really mean didly squat - but the Yamaha MX-D1 trashes it into tiny little pieces.

[NOSValves]

Pauln--

I understand your intentions which are good, but I don't think your distortion definitions fit the more classical explanations. But, your point is well understood anyway. Audio preferences are a belief system, however, not a science. You can't explain various distortions to someone and have them adopt that preference. Anymore than I could explain the Church of the Beaver and have someone switch over from their own Church of the Big White Cloud. Doesn't work. Doesn't play. People come into these belief systems in a million different ways and for a lot of different reasons. Sometimes people hold one system forever, sometimes they change frequently. Usually that is based on direct experience, or faith in a particular trusted guru or chief. Matti Otala, or Peter Qvortrup or Nelson Pass, (or even Julian Hirsch!) and so on. Then a tribe is formed. And, that tribe will do war with all others over these new profound beliefs. Let's face it - men like war, and SET amps are just as good an excuse as anything else to gather some scalps.

Wow now is that an excellent explanation of the human nature of are hobby or what...............

[garyrc]

Does any one measure TIM distortion any more? PWK, c 1977 or so, suggested it be named Otala distortion to honor the man who discovered or first intensely studied it. Has it turned out to be important with certain amps?

PWK, at least in the material I read, called Doppler distortion Frequency Modulation distortion ... he didn't call it IM in those articles. He apparently thought it was a very serious problem in most loudspeakers,

As to ordinary IM, it was often singled out by advertisers and hobby writers (Martin Mayer) as the worst known type of distortion in amplifiers (all tube, then) in the mid 1950s. McIntosh characterized it as the most noxious type of amplifier distortion, made of byproducts harmonically unrelated to the tones being fed into the amplifier, as opposed to harmonic distortion, which was related i.e., odd or even order multiples.

The ear is supreme. Someday, we might be able to factor analyze (and measure!) a few types of distortion that explain all of the major subjective differences we hear.

[Parrot]

Anymore than I could explain the Church of the Beaver and have someone switch over from their own Church of the Big White Cloud.

I believe many guys here pray at the Church of the Beaver.

[NOSValves]

Anymore than I could explain the Church of the Beaver and have someone switch over from their own Church of the Big White Cloud.

I believe many guys here pray at the Church of the Beaver.

I hear a chapter of that church is located in Greece and has broken all records for evangelist recruitment.

[pauln]

OK, obviously only a few are interested in a distortion discussion, but a few are interested in the Church of Beaver, so here it is...

http://www.fpcbeaver.com/

[coda]

The Look of Harmonic Distortion

adapted and expanded from Steve Bench

Fig. 1: Pure sine wave, smoothly symmetrical.

---

Fig. 2: Add 5% second harmonic: Waveform top narrows, bottom widens,
waveform retain smoothness. Asymmetry correlates to distortion.

---

Fig. 3: Odd order harmonics (3rd, 5th, etc.) cause symmetrical
distortion. Adding 5% third harmonic retains smoothness but fattens
both top and bottom of wave crests.

---

Fig. 4: Higher, even-order harmonics appear more evidently. Adding 5%
2nd-, 2% 4th-, and 1% 6th-order harmonics causes sharper top crests and
flatter bottom troughs that indicate higher order distortion components.

---

Fig. 5: With 5% 3rd-, and 2% 5th-order harmonics, symmetrical
distortion indicates the presence of odd-order harmonics, and the
flatened crests indicate higher-order components.

---

Fig. 6: Most amps suffer both even- and odd-order distortions. With 5%
2nd-, 2% 3rd-, 1% 4th-, 0.5% 5th- and 0.2% 6th-order harmonics, the
result looks better than the less overall but more concentrated THD
shown in Fig. 5.

---

Fig. 7: Reversing the distortion spectrum (THD 0.2% 2nd-, 0.5% 3rd-, 1% 4th-, 2% 5th- and 5% 6th-order harmonics).

While the THD in Figs. 6 and 7 measure the same, the characteristic of Fig. 7 looks and sounds much
worse. A distortion spectrum of decreasing amplitudes with increasing
harmonic orders definitely looks and apparently sounds better than one
in which higher harmonics predominate, even with lower overall THD.

Interestingly, the Radiotron Designer's Handbook (the big red bible)
notes that most listeners only begin to positively identify distortion
as the composite THD reaches 5%, with only some listeners noticing
slight distortion at 3% THD. In 1945, they were of course listening on
tube amps; it may be that people listening on transistorized amps can
detect lower overall THD not so much for any difference in quality but
due more to the widely different harmonic spectra between the tubed and
transistorized amps.

Just as knowing speaker power handling capability without also
knowing speaker sensitivity is relatively meaningless, knowing THD
without harmonic distortion spectral distribution is at best
misleading. Composite THD figures appear to be wild
oversimplifications--it's audible to almost everyone that 5% of
3rd-order harmonic distortion sounds dramatically much worse
than 5% of 2nd-order harmonic distortion. And just as each instrument
has its own unique spectral signature that can vary over time and with
stimuli, so too do amplifiers and the complex systems they form with
wires, speakers, enclosures and listening environments. Seen in this
light, amplifiers are every bit as much a scientific instrument and a
work of art as any other system component.

Waveform equation: y = cos(x) + (cos(2*x)*(%of 2nd)) - (cos(3*x)*(%of
3rd)) + (cos(4*x)*(%of 4th)) - (cos(5*x)*(%of 5th)) + (cos(6*x)*(%of
6th))

[coda]

The Many Faces of Distortion

A look at the various types of distortion and the results of an
interesting experiment involving counter-Electro-Magnetic force (EMF).

By Jean Hiraga

Translated by Jan Didden

Glass Audio, May 2005, Pages 40-49

Distortion in audio, defined as a lack of fidelity with respect to a
reference, applies to an amplifier when the output signal the amplifier
delivers is not exactly the same as the signal applied to the input.
Even if it is possible to classify it in different categories,
distortion remains difficult to recognize "in the field," in the
presence of a music signal.

Since the birth of the first amplifier circuits for low-frequency
applications, designers have searched to battle all forms of distortion
which lead to a deformation of the signal to be reproduced. Basically,
distortion can be subdivided into many dozens of categories, one of
which is the type known as "nonlinear," or "amplitude distortion."
This, in turn, exists in different forms: amplitude-frequency
nonlinearity, harmonic distortion, intermodulation distortion (which is
produced when the amplifier is presented with two or more signals
simultaneously), transient distortion, phase distortion, frequency
distortion (where the amplification factor is not constant over
frequency), and scaling distortion (which arises when the amplification
factor varies with signal amplitude).

In the case of the power amplifier, these various types of
distortion intertwine themselves with those produced by the loudspeaker
driver and the speaker acoustic enclosure, and their association can
give ruse to other amplifier stability problems or even re-inject into
the amplifier as a "Counter-Electro Magnetic Force" (CEMF) signal sent
back by the loudspeaker. We will look at it later.

STEADY-STATE AND TRANSIENT HARMONIC DISTORTION

We speak of harmonic distortion if an amplifier generates -- as a
result of a signal to be amplified, for example a 1kHz since -- one or
more harmonics of even or odd order of a certain level: 2kHz, 3kHz,
4kHz, 5kHz, 10kHz. This form of distortion will more or less strongly
alter the original signal and its harmonic envelope and will produce
timbre changes that have been the subject of attempts to evaluate,
quantify, and classify since the beginning of electroacoustics.

To speak about harmonic distortion is also to speak about harmonic
sounds and dissonances, much of the basics that have given music its
famous chromatic range made up from the 12 notes in the tempered range.
Our sensitivity to consonant and dissonant sounds merits some
explanation. In the case of light and vision, the mix of blue and
yellow produces a kind of harmonic result -- green -- which, in
isolation, no longer allows you to discern the original components,
yellow and blue.

Figure 1. Test procedure allowing an audible analysis of supply instabilities in an amplifier reproducing a music signal.

Our perceptive system for sound functions quite differently. If you
play two notes simultaneously on a piano -- and "do" and a "sol" -- you
hear the two notes as a harmonic fusion while still being able to
discern the two. The color "white" can be considered as such a perfect
harmonic mixture of the seven colors of the rainbow that our eyes are
unable to discern the components. Even if this example is applicable
for light and vision, it is not at all the same in the case of sound.

White noise -- a very complex sound that you could transpose into
white light -- is not audibly perceived as a perfect fusion of myriad
pure tones. It is actually perceived as a great number of tones, a
diversity of sounds giving the impression of being badly mixed.

This extraordinary capacity of the ear to analyze a sound as complex
as white noise proves the fact that these tones -- however close or
numerous they are -- are not sufficient to fuse into a single unique
sound, and impossible to generate so that that you could baptize it
"white sound." It is the German Georg S. Ohm (1789-1854), a physicist,
to whom we owe the fundamental laws of electrical current and also the
contribution of this fundamental faculty of the ear known as "Ohm's law
of acoustics."

Figure 2. Interface Inter-Modulation distortion test under load
conditions, designed to simulate the occurrence of a signal generated
by the speaker counter-EMF, fed back into the amplifier.

HARMONIC SOUND, DISSONANT SOUNDS

The study of harmonic sounds and dissonant sounds goes back many
centuries. Interested readers should avail themselves of the works of
Zarlin (Italy, 16th century), the author of the "Zarlin Scale," also
called the physicists scale or diatonic scale; the author of the
"Zarlin Scale," also called "the physicists scale" or diatonic scale;
the discussions and research with regard to the tempered scale and the
exact pitch of the twelve tones of which it is composed; the work of
Marin Mersenne, the author of a famous piece titled "The universal
harmony"; or the often quoted works of Herrmann von Helmholz published
in 1862 under the title "On the Sensation of Tone."

It is from this work that we can extract a fundamental
characteristic of our auditory perception system: the degree to which
intervals within an octave are harmonic or dissonant. We also owe a
debt of gratitude to other researchers such as Fletcher, Zwicker, S. S.
Stevens, and Steinberg, whose important work deals with frequency
differences between pure tones and their degree of consonance or
dissonance. This research greatly facilitates the study of the
subjective influence of harmonic distortion generated by an amplifier.

We are especially indebted to two researchers, Wegel and Lane, for
an important basic study from 1930 on the analysis of amplifier
harmonic distortion and its subjective influence. These scientists
determined with great precision the respective level of each harmonic
enabling us to perceive -- thanks to the effects of successive masking
and multiple harmonics -- the illusion of a pure tone devoid of any
harmonic distortion. They concluded that for a fundamental of 400Hz,
heard at a level of 76dB SPL, the 2nd, 3rd, and 4th harmonics need to
have a level of 61dB, 58dB, and 50dB to be audible.

The means available at the time did not allow analysis of harmonic
levels of higher order. These experiments could only be realized from
1960, at which time it was shown that for harmonics of order 15 to 20,
these harmonics play a role even at levels less than 0.0008% of the
total emitted acoustic energy! Together, these well-executed studies
allow us to understand why amplifiers, however perfect they may appear
in measurements, still produce large distortion, and specifically a
very unstable for of distortion because it results from a signal that
essentially consists of musical transients. It also explains why
certain tube amplifiers (not all, far from it!) or some transistorized
amplifiers reproduce very beautiful, very harmonic sound.

However, these finding must be taken in context. Consider the fact
that both an amplifier and a loudspeaker consist of several stages
connected in series and also in loops. Each of these stages gives rise
to its own specific type of distortion which is fused with that of the
other stages, thus forming a global system that is impossible to
comprehend in the lab once the sinusoidal signal is replaced by music.

"SOFT" AND "HARD" DISTORTION

Figures A through D show a few characteristic examples of harmonic
distortion as a function of output power for three basic frequencies
covering almost the complete audio band, namely, 40Hz, 1kHz, and 10kHz.
Curve A, called "soft" distortion, is often found among amplifiers
lacking feedback. You can recognize it by a distortion level which is
not very small, but increases in a very regular way as a function of
the increase in power output.

The best among them have the advantage of producing the same
distortion at the same power level over much of the audio frequency
band. The majority of the amplifiers that produce this "soft"
distortion also show "soft" clipping. When clipping a sinusoidal signal
it becomes a curve whose peaks are not cut off but only lightly
flattened, which makes the onset of saturation much less audible. The
curve in Fig. B, called "hard" distortion, which is more common,
generally results from a high level of feedback. The harmonic
distortion level is low or even very low over most of the audio band.

Harmonic distortion rises when the level approaches the saturation
point, the peaks of a sinusoidal signal almost always forming a flat,
cut-off shape, generating higher order harmonics and a very
objectionable sound. Curve C corresponds to an amplifier in which the
nonlinearities cause an increase or a decrease in harmonic distortion
levels at certain frequencies and certain power levels. You may find
this (but not always) in circuits equipped with power MOSFET
transistors, active components whose known disadvantage is the high
input capacitance. You can also find it in hybrid topologies in which
the distortion generated by one stage is partially compensated by the
distortion of another stage, of which the audible quality varies case
by case. You'll find curve D in any type of amplifier, tube,
transistor, or hybrid. It results in distortion levels much higher at a
higher frequencies, which can, in many cases, produce a sound that is
hard, gritty, or objectionable.

SUPPLY INSTABILITIES

The majority of amplifiers rely on a basic supply circuit,
consisting of a supply transformer with one or two secondary windings
connected to rectifier circuitry followed by a capacitor filter or by
RC or LC pi-filters. Because the supply is usually common to both
channels and connected to each stage forming an amplifier channel, the
input of a signal to the amplifier being amplified stage by stage has
the secondary effect of generating a myriad of different current draws,
shifted in phase or delayed, which will be combined with secondary
effects related to different phenomena and to several components, such
as:

• various inertias related to charge and discharge times of the filter capacitors;
• transient behavior of the supply transformer, the rectifier diodes, and mains filters;
• variations in the magnetic field emitted by the supply transformer and possible influences on the audio circuits;
• irregular
  behavior of the supply if frequencies directly related to the main
  frequency (for example, 50Hz, 100Hz, 150Hz) are being amplified;
• rattle-like phenomena, resulting from a cascade of transient signals (high-level impulses) that leave residual instabilities;
• sagging,
  often very strongly, of the supply voltage in a loaded state (which
  could reach 50V in badly stabilized tube amplifiers), with the severe
  consequence of an instability in the different operating points of each
  amplification stage followed by inertia phenomena related to the
  charging time of the filter capacitors.

Figure A: Soft distortion. Often found in equipment without feedback.

Figure B: Hard distortion. The classical case, with a rapid rise near the saturation point.

Figure C: Irregular distortion. Due to partial cancellation of the distortion at certain power levels.

Figure D: High-frequency distortion. Similar to Fig. B, but with higher distortion at higher frequencies.

Figure 3: Comparative spectral analysis of amplifiers subjected to
the transitory IIM distortion under load conditions show in Fig. 2.

a. Curve 1: Original composite signal with its two components at 50Hz and 1kHz.

b. Curve 2: Output signal of an amplifier presenting a very good performance at this test.

c. Curve 3: Output signal of an amplifier with excellent classical
test results for harmonic and IM distortion (less than 0.008% at half
power over most of the audio band), but showing strong instabilities in
this test, which could be the cause for its "unexplainable" displeasing
sound.

d. Curve 4: Output signal of the same amplifier as in Curve 3, but
at higher power. We see that the nature of the instabilities has
increased and changed, predicting unstable behavior at other power
levels and frequencies.

e. Curve 5: A tube amplifier with low feedback, with harmonics and sub-harmonics of the two test signals standing out.

You can easily verify this type of distortion generated by the
supply based on the experiences with the circuit in Fig. 1. It consists
of extracting from an amplifier fed by a music signal (by using an
isolation capacitor) the AC instability component from the supply,
amplifying it, then feeding it into the input of another amplifier to
listen to the spectral composition and amplitude envelope of that
component. Subject to a listening test, this signal can take various
forms: muted, sharp, or shrill. It can -- as the amplifier includes
this or that regulator or certain types of circuits -- generate
distortions emitted like salvos, by bursts during transients, making
you think of a tuner being slightly mistuned next to a radio station.

POWER INTERFACE IIM

We all know Matti Otala, a Finnish researcher who discovered the
origin of an obscure type of distortion, Interface Intermodulation
Distortion (IIM). This new form of distortion, found as a result of a
new measurement method, is caused by the amplifier design: the
bandwidth of each stage, group propagation time, delay introduced by
the various stages with impact on the feedback loop action during
transients. Among the different measurement schemes proposed to prove
the existence of this type of distortion, there is no lack of interest
in those that simulate the appreciable energy caused by the
counter-electromotive force of the loudspeaker and the acoustic
enclosure, which is re-injected -- not as a voltage but as an energy --
into the output of the amplifier -- while the amplifier itself is
reproducing a different frequency.

Actually, the classical measurements (harmonic distortion,
intermodulation distortion according to the SMPTE norms) do not allow
detecting it. The basics of this method, which was proposed about 20
years ago by a team of researchers from the University of Musashi,
Tokyo, are still relevant today. They are depicted, with some
extensions, in Fig. 2.

The method consists of injecting a 1kHz signal at the input of the
amplifier under test to obtain a nominal 15W power into the load at the
output. This is either a pure resistive 8-ohm load or a loudspeaker. A
low output impedance power generator, in turn, through a non-inductive
250-ohm / 1000W resistor and a LC filter to suppress the 1kHz band
(self-induction of 7.5mH/15A plus capacitor 3.3uF), inserts a 50Hz
signal into the terminals of the load or the loudspeaker. You thus
recover the composite signal present at the load or loudspeaker
terminals. This signal is then fed into an audio spectrum analyzer.

As shown in the figure, the composite signal is returned to the
amplifier and its input, because it contains a feedback loop. By
injecting a second signal into the load, with a frequency much lower
than the signal being amplified, the counter-electromotive force is
simulated which the loudspeaker would inject into the amplifier.

This secondary signal follows very closely in the time domain and
the amplitude domain the envelope of the signal being amplified, and is
then more or less quickly attenuated and quickly decreases in
frequency. These two effects are the result of the electromechanical
damping of the moving mass, the air load of the membrane, and the
mechanical friction which slows down the movement until the moving
parts return to their rest position.

Curve #1 in Fig. 3 shows the original composite signal across the
purely resistive load, on the left side of the 50Hz signal, and a small
residual harmonic (100Hz) from the low-frequency power generator. Curve
#2 shows the result from a high-quality amplifier with no IIM
distortion, phenomena whatsoever. Curve #3, on the other hand, shows an
amplifier having excellent harmonic and intermodulation distortion
figures (like an average value of 0.008% at half power in the middle of
the audio band and slightly more above that) but showing, under these
test conditions, large problems of IIM distortion under power.

It is interesting to note, in passing, that this same amplifier,
when tested with a slightly larger power output, changes its behavior
and produces, as seen in Curve #4, an even higher IIM with a completely
different shape than in Curve #3. The fact that these results vary
widely from one amplifier to another makes us wish to know its impact
on the sound reproduction quality of each.

It has been effectively shown on the spectrum analyzer that
listening to amplifiers with anomalies as bizarre as those seen in
curves #3 and #4 have a lack of finesse, bad timbre, or sound
inexplicably "hard." However, many tests have shown that amplifiers
with relatively high distortion levels because of low feedback factors
can present, in this type of power IIM distortion, strong disruptions
without being unpleasant to listen to -- far from it. That is the case
for the model of which the measurement is shown in Curve #5, a mono
triode amplifier equipped with a 10A/801A triode.

Curve #5 shows elevated distortion levels, with a 2nd harmonic at
2kHz and harmonics of the 50Hz signal, all without any other
distortions like those in curve #3. Despite these apparent defects,
this amplifier reveals itself in listening sessions to be at least as
good as the one shown in curve #2. Anyway, you not lose sight of the
fact that you are measuring two conceptually very different pieces of
equipment, of different nominal power, for which the other types of
distortion hardly have a chance to be the same.

Dozens of pages of would not be sufficient to examine one by one the
different distortion types generated by an amplifier and by the
amplifier-loudspeaker combination. That is the reason for the
importance of critical listening sessions under a strict protocol,
despite its limitations and risks of errors, which is seen as the only
evaluation method based both on a musical signal as well as
simultaneously taking into account a large number of parameters.

1. Reprinted (without figures) and translated from Revue du Son & du Home Cinema, Nov. 2003, "La Distortion dans tous ses etats."

2. Translating (or rather transculturizing) this article from French
into English, neither of which is my mother tongue, has been an
interesting experience. I am indebted to Pascale Genet of the School
for French as a Foreign Language in Montpelier, France
(lefrancparler.fr) for numerous tips and corrections.

[oldbuckster]

Why does everything become so TECHNICAL on this forum? Anyone who listens to ROCK music knows that distortion is part of it. All the great guitarist use distortion one way or the other.....................Sometimes I think this forum is full of.................DISTORTIONS.................

[jacksonbart]

nice beaver

[oldbuckster]

JACKSON.................is that your best Beaver Shot????????? Do you think ol' EC ever used distortion? Jeff Beck, he would never use distortion, would he? Jimmy Page, never, ever, would think of using distortion........................Oh I forget, the topic was about amps, and distortion.........silly me...........

[oldbuckster]

Buckster--

I think the concept is that you don't want a NEW distortion to change Jimmy Page's distortion into Stevie Ray Vaughan's distortion. Each ought to come through in tact.

Well, sorta'......................my point is that distortion does have it's place in Rock music..................Yeah, your right...................

[garyrc]

I agree with mdeneen.

1) If an artist gets exactly the sound that artist wants, using all of the available means, including distortion, in a world (music and all of the arts) where small differences count, the last thing wanted would be additional distortion to change or mask that fine honed texture.

As the two great San Francisco Bay Area mavens of Klipsch horn speakers (Joe Minor and Don Helmholtz) watched distortion become an aesthetic means of Rock, some funny things happened. Joe said something like, "I thought High Fidelity was dead, but all of a sudden more and more people wanted low distortion speakers because the musicians' distortion sounded more authentic on them." I heard that in the very early days, the Dead borrowed Klipschorns from Helmholtz for a concert. Naturally, they were probably too unwieldy to become a permanent fixture, and other manufacturers were coming up with speakers that were portable, with even higher clean SPL.

2) During the transition (no pun intended) from tubes to solid state, JBL warned that there could be such a thing as too much damping. I think that one thing they did with the equalizing cards they sold to match their energizers to their speakers was to provide the amount of damping appropriate to the particular JBL speaker system the consumer told them they would be using. At least that was the advertising.

[DrWho]

Not me. I want really bad music to sound good.

It's called Bose...

[pauln]

Actually, OB raises an interesting point about distortion - what if the original signal is already purposely distorted, especially highly distorted as is common in modern electric guitar?

Yes, one would think that you want to reproduce that distorted signal as closely as possible to the original sound (what the artist intended), but what if your system is not perfect and has its own distortion. Now the two distortions are combined - so what happens?

Some systems might increase the appearent distortion sound, but I imagine some distorting amps might change the original in a way that makes it sound clearer (?).

Would it always be required to test the amp's distortion with clean signals of clean instruments? Then infer that the amp's reproduction of distorted sounds is correct?

Or does a reproduced distorted signal do things that 'emerge' independently in it's effects on the amp and speakers? At high levels I would think so.

Also, allowing for fair comparison (same level, same volts, same heat, (?) etc), does the amp or speaker have a more difficult job with a distorted signal? At higher levels I would think so... I'm thinking here of the amp and speakers trying to play waveforms that deviate from curvy to more clipped and squared off shapes.

For that matter, does the speaker really "know" the difference between a distortion in the origianl signal amplified cleanly from an amp, and an amp just distorting itself?

Finally, what relavence do the specifications of the amp and speaker have when comparing the playback of clean natural instruments vs heavely distortion music - do the specs still make sense in both situations? Think about it...

[jacksonbart]

I want her distortion

[pauln]

There's really no such distinction (to the amplifier) as clean signals and distorted ones. If you look at a violin note on a scope and a Jimi Hendrix guitar note, you'd be hard pressed to visualize any important distinction. A sine wave may be regarded in physics as a pure tone because it's path can be plotted by a simple formula, but instruments don't produce sine waves in that form. A vibrating string on some instrument produces a complex series of harmonics add to the vibrations of the wood and other surrounding surfaces and so on. The crazy waveform that results does not consist really of clean tones plus distorted tones. All of these things we call signals are nothing more or less than "a change of voltage over time," - a two dimensional plot or transfer. The amplifier doesn't know a sine wave from a C-major chord. It just knows the "change in voltage over the change in time." Further, to the signal itself, bad enough how crazy it is for a violin string, but now sum up an orchestra through a microphone(s) and think of that composite signal.

So, any amplifier should simply take the change in voltage over time and make it bigger. But it can't. It can't because the amplifier isn't theoretical, it is real and suffers all the limitations and imperfections of real things - like friction in a car. So, a guy plays a violin captured by a microphone with distortion which gets added to the mixer with distortion and then the cutter with distortion then the pickup with distortion and the preamp with distortion and the amp with distortion and the speaker with distortion.

Well, a violin will have high harmonic components, but Jimmy's Big Muff Pi genereated square waves, which a violin can't do.

I know what you are saying - what I am wondering about is the waves that have the flat tops - the ones that request the speakers actually hold an excursioned position for a breif amount of time. This would never happen in natural instrument playback.

For some reason, I think an intrument that makes a waveform that has a flattened top/bottom would be a hard thing for the speaker to produce - since it incorporates brief peices of what would be considered DC.

But the question is - is this different from amp clipping? I think it is, then I think it is'nt...???

[oldbuckster]

Gentlemen; "It's Only Rock and Roll".............it's all a BIG Distortion............EH????????........"But, I like it".............

[DrWho]

In fact, in order for any device to pass through a square wave, it needs an infinite frequency response...there is no way around that fact.

[MitsuMan]

*Yawn*

[*-)]