Talk:Distortion

From Wikipedia, the free encyclopedia

This article contains material from the Federal Standard 1037C (in support of MIL-STD-188), which, as a work of the United States Government, is in the public domain.

Contents

[edit] Definition of 'Distortion'

Altered def of distortion into more general form. I know its not perfect but better than it was. Any comments on this def would be appreciated. Light current 21:29, 26 August 2005 (UTC)

  • New def does seem better
  • I agree with NeilUK,noise causes a difference,but as such noise and hum are not lumped with standard forms of distortion.Perhaps a section on misc distortion is required? Could include noise,hum,crossover distortion,etc
  • Also,my image on harmonic distortion was removed.I had tagged it wrongly,was that why it was removed? I feel more images are also required on this section to make the different forms clearer.
  • I could contribute means of reducing mentioned distortion as well. Would this be too detailed for Wiki,or would it be useful?Xcentaur 16:58, 12 March 2006 (UTC)

Image of dist w/f removed because it showed a non physically realisable and inaccurate waveform. All cycles should look the same - yours didnt and the wave was going backwards in time which is impossible.--Light current 20:51, 12 March 2006 (UTC)

If the "expected" output is for non-linear behaviour, then a deviation from this will be consisdered distortion under this definition. Perhaps it should be that the system output is different from the input, even when the non-distorting effects of frequency-independant gain and delay have been allowed for. Noise causes a difference, but is not usually lumped in with the other distortion mechanismsNeilUK 09:25, 12 March 2006 (UTC)


"Interestingly enough, many solid-state distortion devices attempt to emulate the sound of overdriven vacuum tubes - even though the most famous recordings of distortion were achieved through the use of solid-state effects."


Wheres the proof of this? --60.231.45.69 17:01, 11 December 2005 (UTC) Added what an undistorted signal is to the definition and explicityl excluded noise and hum.

Expressing disrtion in terms of the transfer function shows that there is really only linear distrtion (filtering, that is gain and phase as a function of frequency) and non-linear distortion (gain and phase as a function of input amplitude). I have not had time yet to go through the rest of the entries making them consistent. The "amplitude distirotoin" entry which is currently defined as non-linear is not strictly correct, as even linear disrtiotn can alter the shape, that is the amplitude, of a signal. "Frequency distrtion" is not consistent with all the other "types", where "X disrtion" means disrtion of X, however what is described under frequency disrtirotion is not a disrtirotiorn of frequency (hey, this keyboard can't spell disrtirotoin :-\). Linear disrtiortion affects gain and phase as a function of frequency, group delay is just another way of expressing the phase disrtiortion, it is not a different type of disrtiortoin in its own right. I am a little reluctant to go through the whole article losing the more folksy but inconsistent descriptions, as it is usually me that is saying that Wiki aims a little too high in terms of minimum required knowledge of the reader, but equally I do not want to confuse people by leaving inconsistent terms around. My aim would be to get consistency throughout, in terms of linear and non-linear, with examaples from audio and radio, but not too high a level. Most of the stuff I have added is on "waveform" distortion, the language and concepts apply less so or not at all to images, maps, objects etc, so maybe an explicit seperation of these is in order?. NeilUK 21:15, 12 March 2006 (UTC)

Added a diagram and changed the words around that areaNeilUK 10:43, 13 March 2006 (UTC)

Being an electronic calibration engineer, when I deal with distortion, it's normally to do with measurement (or generation of) unwanted signals. Distortion is a measure of the unwanted signal as a fraction of the fundamental. For example, a signal comprising of a Fundamental 1V @ 1kHz and a Harmonic 10mV @ 2.2kHz. This signal would have 1% distortion (10mV as a fraction of 1V) or -20dB ( 20*log(10mV/1V) ) Could this entry have a section on Distortion in Electronics and the maths to go with it? hrf 15:37, 1 June 2007 (UTC)

Yea, I know, I should have seen the link to THD. hrf 07:59, 6 June 2007 (UTC)

[edit] Harmonic vs intermodulation

The article says:

When output is not in this portion, two forms of amplitude distortion might arise

  1. harmonic distortion
  2. intermodulation distortion

But is it really correct to call them "two forms" of distortion? If you put a single sine wave through a clipper, it produces harmonic distortion. If you put the sum of two sine waves through the same clipper, it produces intermod distortion. — Omegatron 03:15, 30 March 2006 (UTC)

With a nonlinear device, you need two input signals to get intermodulation dist. You only need one signal to generate harm dist. See mixer--Light current 17:39, 30 March 2006 (UTC)
I agree with what the page says on this!--Light current 22:31, 30 March 2006 (UTC)
I'm asking if it's correct to call them two different "forms" of distortion, since they are caused by the same process and exist in the same device. — Omegatron 05:39, 31 March 2006 (UTC)
I think we can call them two different forms since IM gives a lot more mixing products than pure harmonic dist. They are different processes. Both cause distortion but IMD is much nastier as it splatters mixing products all over the place and not in a simple harmonic relationship to the originating signals.(I think)--Light current 05:43, 31 March 2006 (UTC)
I know they give different results; it's just that the results depend on the input signal, and not on the device. I guess it's ok to call them "forms", but it seems to me to imply that you can have one without the other, which, as far as I know, isn't true. — Omegatron 14:23, 31 March 2006 (UTC)
Yes the cause of the distortion is the same (ie nonlinear device) but the two sorts of dist are treated differently in RF circles as they have greater significance there. I agree that in audio, youll get both sorts with complex programme material as i/p (anything other than a sine wave). But in the RF world the harm dist can be LP filtered out, IM dist generally cant (cos its everywhere). Which is why RF designers are always talking about it!!--Light current 15:00, 31 March 2006 (UTC)
Yeah, I guess it's fine the way it is. — Omegatron 15:43, 31 March 2006 (UTC)


OK. Phew!--Light current 17:13, 31 March 2006 (UTC)

I like the way this is phrased:

Many people confuse the causes or forms of distortion with measures of distortion (see for example Frey 1979). This confusion occurs frequently in popular press articles. Harmonic distortion is often thought to be something different from intermodulation distortion. However, the device under consideration has an inherent nonlinearity which will generate harmonics, intermodulation products or both when stimulated by a signal. If the signal is a single tone, only harmonic products may be generated. Both harmonics and intermodulation components will be generated when the excitation is a multitone signal. Digital audio or other sampled data systems may shift the harmonic and intermodulation frequencies due to the folding action of the sampling process. This can, for example, result in harmonics appearing at frequencies which are not harmonic multiples of the input.

– Comparison of Non-linear Distortion Measurement Methods]

— Omegatron 00:00, 5 August 2006 (UTC)

Yes that seems to echo what I was saying, but its put in a better way! 8-)--Light current 12:59, 5 August 2006 (UTC)

[edit] Distortion and output power

Does distortion actually increase the output power of an amplifier such that the percieved increase in volume is solely due the that power increase? Well, say you had 20% distortion. Does that mean that the output power is increased by 20%? If so, what is 20% in dB? Would you hear any difference in loudness? No! OK. Some fuzz boxes actually do clip. This will double the power out of the amp. This is a 3dB increase. Can you hear a 3dB increase? Yes - just about!--Light current 16:58, 17 April 2006 (UTC)

Yes, most intentional distortion is a form of clipping. It allows more area under the curve for the same peak amplitude. It's a minor issue, but it is slightly louder. — Omegatron 17:12, 17 April 2006 (UTC)

[edit] Use of distortion in rock, and any other genre of music

It has intrigued me how greats like Metallica, Nirvana, Alice in Chains, and others have used such an unusual source to provide a more unique and (pun intended) distorted sound. The talk box, wah-wah pedals, and distortion used in "Man in the Box" by Alice in Chains have no match from any rock or band over all. brainybassist 22:59, 19 April 2006 (UTC)

[edit] Difference between undistorted and distorted electric guitar?

For example a sound file of an undistorted guitar, and then a distorted guitar?Ollie the Magic Skater 22:44, 11 May 2006 (UTC)

Fuzzed guitar

Several power chords, played clean, then with different settings of a Big Muff Pi.
Problems listening to the file? See media help.

[edit] How much should Distortion page cover guitar?

http://en.wikipedia.org/wiki/User_talk:Light_current#Distortion_page:_Guitar_section MichaelSHoffman 19:23, 6 August 2006 (UTC)

A new Wiki entry may be needed: Distortion (electric guitar). It's a special topic and I have info ready to go. I see a tendency to downplay guitar stomp boxes and guitar amps, by reductionistically subsuming them into other, "straight" topics like straight musical instruments, straight amplifiers, and straight distortion as defined by people wearing bowties and sitting in armchairs.

Guitar distortion is an entirely different, distinctive topic. "Straight" treatments of guitar distortion in terms of other existing categories miss the essence by distorting the subject into something it's not. The goals, objectives, and techniques of guitar distortion are utterly different than any other field or isolated topic.

You could be an expert on audio distortion, on guitars, on amplification, on effects pedal circuits, and yet still provide no real insight into the special topic of guitar distortion sounds. Even the existing books on guitar gear have trouble hitting this target, of how to effectively manipulate guitar distortion. Amptone.com; MichaelSHoffman 19:23, 6 August 2006 (UTC)

Guitar distortion should go on guitar effects page apart from a brief mention here to say that it is in fact used s a guitar effect. THis page is a general page on distortion; the latest edit to this page tended to unbalance the page far too heavily in favor of guitar dist. Ishall move the remainder to guitar effects and paste Mikes latest edit ther as well.--Light current 19:35, 6 August 2006 (UTC)

Ok, thanks, I'll look at the pages later and continue considering whether a new entry is needed that gives a proper central focus to the specific topic of how Rock guitarists shape distortion textures for electric guitar by using guitar amps and guitar effects pedals. MichaelSHoffman 19:51, 6 August 2006 (UTC)

If you lokk at Guitar effects page, youll see all your content on distortion there, but the page does need balancing up with the other effects. Im sure you could help there!--Light current 20:03, 6 August 2006 (UTC)

[edit] Distortion page: Guitar section

moved from my talk--Light current 20:01, 6 August 2006 (UTC) Hi Light current,

It appears that you hastily reverted my improvements to the Guitar section of the Distortion page without seeing that the result of your reversion contradicts your stated reason for the reversion. Your stated reason for the reversion is that the page isn't about distortion in electric guitar. Yet your reversion caused the page to revert to its old state, which in fact *has* a section about distortion in the context of guitar amplification. ...

The distortion page should either have my improved version of the previously existing guitar amp distortion section, or should have the previous version of the guitar amp distortion section removed, replaced by a link to the other page such as Effects unit or Electric guitar or Instrument amplifier. ... MichaelSHoffman 18:48, 6 August 2006 (UTC)

Michael, I have moved your contribution to the revived Guitar effects page where I think it sits more comfortably. I should have done that before rather than reverting > Sorry! It was a bad day yesterday. It may be that the page on effects pedal should be merged int this page. What do you think?--Light current 19:49, 6 August 2006 (UTC)

I agree that the generic "Effects pedal" page should be merged into the "Guitar effects" page, because more guitar-dedicated articles are needed. There are several pages that presume to be instrument-neutral but are in fact all about electric guitar, and should be straightforwardly titled and admittedly positioned as such. The exceptions prove the rule; these are guitar articles and it does more good than harm to position them specifically as such, when they have been written by guitarists for guitarists.

[I moved the list of proposed articles from here to down below.]

The guitar application of a topic should not be subsumed as though it were a minor subcase the subject. Wiki has tended to suppress electric Rock guitar in the technology articles. There is a major precedent supporting my proposal: notice that "Electric guitar" is not subsumed into the "Guitar" article. Neither should Guitar distortion be subsumed into Distortion. Same with Guitar attenuators, and Guitar amps.

Guitar amps are more like an essentially independent subject than a subcase of Amps. Guitar amps have outgrown the Instrument amps page, and Guitar attenuators have outgrown the Attenuator (electronic) page. Guitar applications of technology need their own dedicated pages. Michael Hoffman, BSEE, Amptone.com MichaelSHoffman 20:44, 6 August 2006 (UTC)

Link your proposed pages to see whats already here. Do you really think a separate page on guitar distortion is warranted? Or would it be best lumped with all the other guitar effects?--Light current 21:12, 6 August 2006 (UTC)
Also theres one you may have missed called Bass instrument amplification--Light current 21:17, 6 August 2006 (UTC)

I linked Effects pedal as well. I didn't see Bass instrument amplification; I see it needs to be cross-linked with Instrument amplifier.

A separate page on guitar distortion is warranted; it is not best lumped with all the other guitar effects. Guitar distortion is the main, major, predominant topic in Rock guitar gear. It's not only a pedal to buy and plug into. It's not merely an effect to add; it's the very essence and central point of reference of Rock guitar tone.

The recent good books on guitar sound (such as Dave Hunter's series), and the magazines (Vintage Guitar, ToneQuest Report), advice to begin with a tube power amp running on the edge of audible distortion, so that as you pluck the guitar strings harder, the amount of distortion and the resulting volume both increase, or pluck less hard to clean-up the tone.

All effects are to be added to that starting-point, that baseline foundation of edge-of-breakup. In that sense, distortion is what electric guitar is all about. Guitar distortion is not a minor subtopic of Guitar amps, nor a minor subtopic of Guitar effects; guitar distortion transcends the separate topics of guitar amps and guitar effects units.

Distortion is the main, central topic in the subject of Guitar signal processing. The burgeoning but controversial field of guitar amp modelling is entirely about various guitar-specific distortion qualities -- it's not about amplification or effects; it's about modelling cataloged varieties of distortion. At the moment, the subject of guitar distortion is spread out among several guitar related and general electronics articles.

The complex and central subject of guitar distortion won't be adequately understood, as long as it is tucked away under "pedals" (which many "amp distortion only" tone-hounds disparage) or "effects" (a term which has overtones of silly unmusical flanging excess obscuring the guitar tone -- obscuring the subtle distortion qualities that have become *the* goal for many guitar tone purists).

The large subject of "distortion basics for guitarists" would outgrow an effects listing. MichaelSHoffman 22:09, 6 August 2006 (UTC)

OK. Go to it! 8-)--Light current 00:48, 7 August 2006 (UTC)

[edit] Proposed Article Titles and Changes

--- FINAL PLAN ---

GUIDING PRINCIPLE: Articles about guitar gear should have 'guitar' in the title.

JUSTIFICATION: The distinction between general theory about a technology, versus the popular *application* of that technology to electric Rock guitar, justifies a set of articles explicitly devoted, in the title, to *guitar* application. Several articles claim in their title to be general-focused, when in fact, they are focused largely or almost exclusively on guitar application. Titles should match common, de facto, popular usage.

PROPOSED ARTICLE TITLES AND CHANGES:

-- Michael Hoffman, BSEE, Amptone.com MichaelSHoffman 17:13, 7 August 2006 (UTC)

Any final comments before this is implemented?

I assume you will be leaving something under instrument amplifier for those musical insts that are not guitars. Otherwise, it looks fine to me 8-)--Light current 17:17, 7 August 2006 (UTC)

Yes. Thanks. MichaelSHoffman 17:20, 7 August 2006 (UTC)

The Instrument amplifiers page was almost entirely about guitar amplifiers, but was positioned as though generic; as a result, the topics of other instrument amps, hi-fi amps, and circuit design are still entangled into the subject of guitar amps, in both articles.

I'd be glad to see people improve this refactoring, but it would introduce a real problem if anyone were to revert one of these pages in isolation. Please discuss here before making any such major changes -- let's move *forward* please.

The refactoring is done. Fine-tuning is invited. MichaelSHoffman 07:50, 8 August 2006 (UTC)

Well maybe someone should try to break out hifi and other inst amps from the guitar articles? What do you think 8-?--Light current 17:12, 10 August 2006 (UTC)

In the Guitar amplifier article, sentences about hi-fi amps, amps intended for other instruments, and amps for bass should be moved to the respective articles: Amplifier(?), Bass instrument amplification, or Instrument amplifier. I've merely added that guitar amps are used to warm up drum loops, to give keyboards or cello a guitar-amp distortion sound, and for blues harp. MichaelSHoffman 02:20, 11 August 2006 (UTC)

"Optics" should be retitled to "2-dimensional distortion", to distinguish it from phase/amplitude/frequency distortion in fiber optics. 2006-08-19 20:34.

Great job! As the original and for a long time the only author of the old instrument amplifier article, I think you've done well (so far... an article is never finished, of course). Andrewa 07:13, 4 October 2006 (UTC)