
	Where results make sense

Topic: Phase distortion

Related Topics

Modulation

Orthogonal frequency division modulation

Fading

In the News (Fri 25 Dec 09)

Northern Trust

Marvin Harrison

Peter Chernin

Gary Locke

Match Play

Penelope Cruz

Mickey Rourke

AR Rahman

Danny Boyle

Hugh Jackman

	Audibility of Phase Distortion
		The observation that phase is very audible under some conditions is certainly not new, and is stated emphatically in an excellent paper by Lipshitz et.al.
		In a correspondence with Dr Lipshitz he pointed out that it the phase of the second tone is 0-degrees instead of 90-degrees, that the asymmetry in the positive and negative directions is greater.
		Note: If the phase of the 400 Hz tone is shifted by 180 degrees, after one cycle of the 400 Hz tone it just repeats, but the 200 Hz tone has undergone a 180 degree phase shift.
	www.silcom.com /~aludwig/Phase_audibility.htm (1808 words)

	SoundStage! Max dB - Seeing Through The Fog (12/1998)
		Phase shifts and time delays as the audio signal passes though electronic components and loudspeakers affect what you hear in your room, although in ways that are not as obvious as THD.
		These phase distortions are static in that they do not change while we listen, so they are not as obvious, again, as tonality or transparency or detail.
		Tube amplifiers, as a group, are worse in respect to phase performance than solid-state amps in general; however, many designers of solid-state amps are either oblivious to designing for minimum phase shift or are convinced it doesn’t matter, so they don’t bother to fix or prevent phase shifts in their designs.
	www.soundstage.com /maxdb/maxdb121998.htm (3859 words)

	Chapter 2
		A frequent argument to justify why phase distortion is insignificant for material recorded and/or reproduced in a reverberant environment is that reflections cause gross, position sensitive phase distortion themselves.
		This increased phase sensitivity may be due to reflections, or standing waves converted into amplitude shift present in the reverberant room.
		A new and important contribution made here was the interrelationship between group delay distortion (a frequency-domain measure) and the corresponding impulse response (time-domain measure) for each all-pass filter, particularly the envelope of the impulse response, and perceived phase distortion.
	www.zainea.com /firing.htm (4814 words)

	Distortion Charateristices of the Analog Section (Site not responding. Last check: 2007-10-20)
		It is our opinion that phase distortion is much more annoying than amplitude distortion because it affects the signal at a node.
		The loss of phase coherence (which occurs with most audio equipment) is analogous to replacing a holographic plate by a photograph.
		It is the preservation of phase coherence which creates the soundstage in Daniels Audio equipment, and allows the instruments to be identified distinctly and unambiguously.
	www.danielsaudio.com /distortion.htm (286 words)

	diyAudio Forums - Crossover points and music power distribution
		Andrew's article also links to Linkwitz's phase discussion, which, ironically, contradicts his position that phase distortion is audible.
		Again, remember that phase and timing between the ears is one thing, phase distortion as introduced by a crossover is another thing.
		Though I believe that phase distortion from crossovers is audible, I don´t think it necessarily have so much with imaging and localization to do, but more about how it sounds and how it affects listening fatigue and such things.
	www.diyaudio.com /forums/showthread.php?postid=518853 (1948 words)

	Correcting Low Frequency Phase Distortion
		The figure shows the distortion in a 150 Hz (approximately) square wave (topmost waveform), when processed by filters with -3dB ‘break points’ at 10, 20 and 40 Hz, both for a minimally distorting one-pole filter (waveforms B,C,and D) and for a four-pole filter having a Butterworth configuration (waveforms E,F, and G).
		The type of distortion introduced in an actual EGG waveform by high-pass filtering is shown in Figure 2.
		In the lower three panels (B, C and D), a compensator with N = 2.5 is employed to reduce the distortion, with the zero introduced by the compensator increasing in frequency from B to C, and at an intermediate value in D that appeared to the writer to yield a minimum distortion.
	www.rothenberg.org /Phase/index.htm (2007 words)

	Phase distortion
		I had convinced myself that the phase distortion of a LR4, 24 dB/oct midrange to tweeter crossover is not audible, Ref.17.
		Phase distortion may increase the crest factor of the waveform (B above) and lead to non-linear distortion in the speaker and/or the ear producing a change in sound character.
		The phase distortion of a 100 Hz acoustic crossover with 12 dB/oct or 24 dB/oct is not audible based upon the above tests.
	www.linkwitzlab.com /phs-dist.htm (1208 words)

	Phase Distortion article
		Phase is easily audible as it is being changed, such as with a component frequency in a complex waveform.
		Ohm's Phase Law in the 1800s claimed that the phase of a waveform has no effect on how the ear perceives it, and in typical circumstances, relative phase differences are difficult to perceive.
		A phase alteration of 180 degrees in high frequencies from a 2nd order crossover would not seem to have any effect on the angle of location, as both sound sources (loudspeakers) are equally effected, yielding no differences in phase between the two ears.
	www.ocf.berkeley.edu /~ashon/audio/phase/phaseaud2.htm (3024 words)

	Doppler Distortion in loudspeakers
		With phase shift, velocity is not relevant - only the variation of distance between source and listener determines the shift, and it can be shown that the peak phase shift coincides with the peak excursion of the cone (positive and negative).
		Phase modulation [Ref 7] is actually very similar to frequency modulation - so much so that some narrow-band FM communications systems actually use PM (Phase Modulation) because it is easier to implement.
		Exactly the same phase shift can be seen simply by disconnecting the LF signal, and manually moving the cone or microphone (slowly) by the same amount, or by using DC or an extremely low frequency to achieve the same result.
	sound.westhost.com /doppler.htm (7400 words)

	PSW Recording Forums: Whatever Works => phase distortion
		phase distortion: Distortion that occurs when (a) the phase-frequency characteristic is not linear over the frequency range of interest, i.e., the phase shift introduced by a circuit or device is not directly proportional to frequency, or (b) the zero-frequency intercept of the phase-frequency characteristic is not 0 or an integral multiple of 2 radians.
		phase shift is a naturally occurring kind of distortion, phase distortion is not.
		In fact Linear phase digital EQ was a Holy Grail for a while (in the early 90's if I recall) until we learned that it didn't really sound any better than good old analog ringing-like-a-bell-all-the-non-linear-phase-delay-in-the-wo rld, equalizers.
	recforums.prosoundweb.com /index.php/t/14158/0 (1650 words)

	SoundStage! Max dB - Technobabble: The Importance and Meaning of Distortions (06/1998)
		Phase distortion – The input signal is a constantly changing voltage—a different voltage at each instant in time.
		This kind of distortion may be a factor in some of the "unmeasurable" differences in components that audiophiles claim to hear but nobody claims to be able to measure.
		If you do find an amplifier or preamplifier claiming very low phase distortion, and graphs or other data are included to "prove" it, chances are fairly good that the designer really did aspire to low levels of phase shift.
	www.soundstage.com /maxdb/maxdb061998.htm (2585 words)

	Phase, Time and Distortion in Loudspeakers
		Phase and group delay are the same for each filter individually, and for the summed output - this means that these two parameters remain the same whether the filter is high pass or low pass.
		One output (in this case the high pass) is reversed in phase to compensate for the phase reversal that occurs in all 12dB filters.
		The phase response of the same speaker is shown in Figure 19, and the sudden discontinuity is simply the way phase is normally shown as it passes 180°.
	sound.westhost.com /ptd.htm (10927 words)

	Phase Distortion
		Of all the speaker ailments, phase distortion is the most critical, the hardest to cure, and probably the least understood by both stereo enthusiasts, and the average consumer alike.
		Using easy-to-understand models, and non-technical terms, this pamphlet will enable you to understand phase distortion and the critical role it plays in the reproduction of music through loudspeakers.
		To understand phase distortion, one must first understand the meaning of the words Frequency and Cycles.
	www.brentworth.com /phasedistortion.htm (1255 words)

	ProSoundWeb.com \| Huge University Tech Talk January 19, 2007
		It has 90° of phase shift in opposite directions for each half of the crossover, so when they sum in polarity, they sum to flat in amplitude and cancel the lead and lag for a flat-phase response as well.
		Since there is 90° of phase shift in opposite directions for the HF and LF portions, the signal of each is 180° out of relative phase.
		This phase delay does not exist in the original signal that the speaker is reproducing and is, therefore, a form of distortion.
	prosoundweb.com /hu/techtalk/tuning_phase (1072 words)

	CAPACITORS
		Even electrolytics can have low distortion provided we take care to avoid reverse bias and keep the signal voltage across the capacitor small, which can be ensured by using a sufficiently large value, and keeping the current low, which is easy in some applications, but not in the case of a speaker coupling capacitor.
		The phase differences between capacitors may be thought to be a problem, and in some applications careful selection is needed, but in the case of an input coupling capacitor for example, the low frequency phase shift from even an ideal capacitor is in principle undesirable.
		Just comparing the two phase graphs the DA effect reduces the phase advance, easily interpreted as a relative phase delay if we mistakenly take the ideal capacitor to be our reference standard, which could lead to the conclusion that DA adds time delay when in this application it actually adds less phase advance.
	www.angelfire.com /ab3/mjramp/caps.html (1490 words)

	4
		"Linear Phase" refers to the condition where the phase response of the filter is a linear (straight-line) function of frequency (excluding phase wraps at +/- 180 degrees).
		The lack of phase/delay distortion can be a critical advantage of FIR filters over IIR and analog filters in certain systems, for example, in digital data modems.
		Minimum-phase filters (which might better be called "minimum delay" filters) have less delay than linear-phase filters with the same amplitude response, at the cost of a non-linear phase characteristic, a.k.a.
	www.ele.uri.edu /~sairajan/fIrandlinearphase1.htm (459 words)

	Apple - Logic Pro - Distortion Effects (Site not responding. Last check: 2007-10-20)
		Compared with this, Logic’s other distortion effects likely tailor around the needs of the classical sound wizard, such as adding a sharp edge to a synthesizer sound or spicing up a drum-loop.
		The difference between both effects is the softer overmodulation of field-effect transistors (overdrive) in contrast to the harder overmodulation of bipolar transistors (distortion).
		The Phase Distortion plug-in is based on a modulated delay line, much like the well-known chorus and flanger effects.
	www.apple.com /logic/distortioneffects.html (424 words)

	AES Electronic Library: On the Audibility of Midrange Phase Distortion in Audio Systems by Lipshitz, Stanley P.; ...
		The current state of our knowledge regarding the audible consequences of phase nonlinearities in the audio chain is surveyed, a series of experiments is described which the authors have conducted using a flexible system of all-pass networks carefully constructed for this purpose, and some conclusions are drawn regarding the audible effects of midrange phase distortions.
		Having satisfied ourselves that phase distortions can be audible, the types of phase distortions contributed by the various links in the audio chain are surveyed, and it is concluded that only the loudspeaker contributes significant midrange phase nonlinearities.
		Confining the investigation to the audibility of such phase nonlinearities in the midrange, circuitry is described which enables such effects to be assessed objectivbely fo their audible consequences.
	www.aes.org /e-lib/browse.cfm?elib=3824 (348 words)

	Linear phase
		The limits on over-all trends in phase response are very generous, and appear not to require special consideration in the design of conventional domestic loudpeakers." He then points out that phase shifts associated with resonances should be minimized by controlling the resonance.
		distortion audibility at high levels is often masked by the distortion generated by the ear itself, and phase differences between the equipment's distortion and that generated in the ear lead to different subjective effects.
		The phase angles of the harmonics of the masker were either constant (all equal) or random.
	home.online.no /~run-alek/linear.htm (2761 words)

	Filters Preserving Phase
		In this chapter, linear phase and zero phase filters are defined and discussed.
		When one wishes to modify only a signal's magnitude-spectrum and not its spectral phase, then a linear-phase filter is desirable.
		That is, both the phase and group delay of a linear-phase filter are equal to
	ccrma.stanford.edu /~jos/filters/Filters_Preserving_Phase.html (411 words)

	Sonic State - News White Crow Spotted, New virtual monophonic Phase Distortion synthesizer takes flight (Site not responding. Last check: 2007-10-20)
		White Crow is a virtual monophonic synthesizer with a very distinctive sound (listen to the sound demos) that uses a unique synthesis method called Phase Distortion Synthesis.
		Phase distortion synthesis is a synthesis method introduced by Casio in its CZ range of synths.
		The phase distortion amount of each oscillator can be modulated by 2 ADSR envelopes, an LFO, and the velocity.
	www.sonicstate.com /news/shownews.cfm?newsid=3104 (373 words)

	Perception of Audio Phase (Site not responding. Last check: 2007-10-20)
		If the monitor system is phase linear, (constant delay), and with correct polarity, a microphone at the listening position will show a large positive impulse when human voice is reproduced and the microphone output displayed on an oscilloscope.
		The relationship of the tones is that the second tone changes "phase" with respect to a harmonic of the first tone at a rate of 360 degrees/second.
		Perhaps the best way to summarize the above observations is to say that the ear may be unable to sense phase, but it is sensitive to the phase relationships between tones and that this sensitivity is level dependent.
	home.att.net /~lemon.j.russell/audphase.htm (782 words)

	"Doppler Distortion" vs."Phase Modulation"
		(t) then there is a 90 degree phase difference in the signals s(t), due to the derivative in equation (3).
		However if the modulations are 90 degrees out of phase, them the two signals are in phase.
		Define the PM case, as done in the approximate Doppler distortion analysis, by the equation
	www.silcom.com /~aludwig/Physics/Exact_piston/PMvsFM.htm (227 words)

	Casio CZ101 (Site not responding. Last check: 2007-10-20)
		Not unlike FM synthesis in some ways, by changing the phase angle of a any of the supplied waveforms, you could alter the harmonic content of the selected waveform.
		With no phase distortion, you hear a sine wave but as the phase distortion is increased and the waveform's phase angle is altered, so the waveform becomes closer to the selected waveform.
		You could control the amount of phase distortion using LFOs and envelope generators that allowed you to go some way to mimicking many typical analogue sounds.
	www.hollowsun.com /donations/casio_cz101 (488 words)

	EDN Access -- 08.18.94 Oscillator lowers distortion and phase noise (Site not responding. Last check: 2007-10-20)
		In addition to its normal role of controlling oscillation frequency, the crystal in Fig 1 also acts as a high-Q, self-tuned output filter, which rejects the noise and harmonics of its input voltage, V
		With an output frequency of 10.7 MHz, second harmonic distortion is -76 dBc, and third-harmonic distortion is -72 dBc.
		Due to the high Q of the crystal filter, the circuit also rejects all out-of-band noise produced by both the four-transistor voltage follower and IC, which results in low phase noise.
	www.edn.com /archives/1994/081894/17di1.htm (307 words)

	diyAudio Forums - Comments regarding "phase distortion" correction?
		If anti-imaging filtration had been standardized for the CD, a phase correction filter might have a chance to work- though it would be FAR better to implement it digitally on the source end, with zero cost to the end consumer.
		But there is no standard, all CD players are different in that respect, and the audibility of these "phase shifts" is somewhat questionable, anyway.
		I really like when he interprets a half sampling period delay as phase distortion
	www.diyaudio.com /forums/showthread.php?postid=84686 (238 words)

	Finite Impulse Response FAQ: Properties
		Because boxcar FIRs can be implemented using only adders, they are of interest primarily in hardware implementations, where multipliers are expensive to implement.
		Hilbert Transformer - Hilbert Transformers shift the phase of a signal by 90 degrees.
		They are used primarily for creating the imaginary part of a complex signal, given its real part.
	www.dspguru.com /info/faqs/fir/props.htm (1054 words)

	purevolume™ \| Hyper Phase Distortion Blaster
		Hyper Phase Distortion Blaster hasn't posted a blog yet.
		Hyper Phase Distortion Blaster hasn't posted any shows yet.
		All songs, lyrics and pictures © Hyper Phase Distortion Blaster.
	www.purevolume.com /hyperphasedistortionblaster (51 words)

	Phase Coherent.com
		Home » Articles » A Primer on Phase Coherence
		Mainly, phase distortion is difficult to test and to prove.
		I CAN HEAR PHASE DISTORTION, at least in this "castanet" sample, on my system, in my familiar acoustical environment.
	www.ocf.berkeley.edu /~ashon/audio/primer1.htm (3054 words)

Try your search on: Qwika (all wikis)