Phaser

[cr_XD]

hello,

my friend has asked me for a simple explanation of what a phaser does, my terms are too fuzzy , so i thought that maybe you could explain it for a total ignorant (where for two). i would really appreciate it.

thanks so much

have fun

btw - not the circuit but the idea, thanx

Edited April 11, 2007 by cr_XD

[biliousfrog]

The phasing effect was originally produced by simply copying the sound onto two analogue tape decks and mixing them together. One tape was run slightly faster than the other, so that one copy of the sound would overtake the other, resulting in a rising then falling effect caused by wave interference. DJs can achieve the same effect by playing two copies of the same record from the same point at the same time.

However, as more practical solid-state electronics and latterly software were used to re-create an approximation of the unwieldy tape-flanging set-up, the term Phasing more specifically refers to a swept comb-filtering effect where there is no linear harmonic relationship between the teeth of the comb (compare this with flanging, where the teeth of the comb-filter are spaced along the frequency spectrum in a linear harmonic series).

A flanger is a subtype of phaser in which the notches are uniformly spaced. In this case, the notches are created by mixing the signal with a delayed version of a signal. Flangers tend to sound more natural, like the "jet plane whoosh" effect, whereas phasers tend to sound more unnatural.

The electronic phasing effect is created by splitting an audio signal into two, electronically shifting the phase of one signal (usually by passing it through an all-pass filter), and then recombining the two signals. The all-pass filter passes all frequencies unchanged in amplitude, but has a frequency-dependent, non-linear effect on the phase of each frequency. The result is a signal whose overall spectrum is shifted by various amounts at each frequency. For example, the phase of a frequency at the low end of the spectrum may be shifted by 1/4 of a wavelength, while a frequency at the high end of the spectrum may be shifted by 3/4 of a wavelength.

Traditional electronic phasers use a series of variable all-pass phase-shift networks which alter the phases of the different frequency components in the signal . These networks do not alter the sound themselves (human ears are not very responsive to phase differences), but they yield constructive and destructive interference when mixed back with the dry (unprocessed) signal. Additionally, the output can be fed back to the input to create a more intense effect. Most modern phasers are a part of a digital signal processor, often trying to emulate analog phasers. Phasers are mostly found as plugins for sound editing software, as a part of a monolithic rackmount sound effect unit, or as "stompbox" guitar effects.

When the filtered and non-filtered signals are recombined, the phase differences between them now cause peaks and notches of reinforcement and cancellation along the frequency spectrum (the so-called comb filter pattern). The degree of phase shift is periodically modulated (usually using an LFO), causing the peaks and notches to 'sweep' up and down the frequency spectrum, producing the characteristic rolling timbral changes of the phasing effect.

A stereo phaser is usually two identical phasers modulated by a quadrature signal; the output of the oscillators for the left and right channels are a quarter-wave out of phase.

(thanks to wikipedia )

Also: http://www.harmony-central.com/Effects/Art...Phase_Shifting/

[cr_XD]

The phasing effect was originally produced by simply copying the sound onto two analogue tape decks and mixing them together. One tape was run slightly faster than the other, so that one copy of the sound would overtake the other, resulting in a rising then falling effect caused by wave interference. DJs can achieve the same effect by playing two copies of the same record from the same point at the same time.

However, as more practical solid-state electronics and latterly software were used to re-create an approximation of the unwieldy tape-flanging set-up, the term Phasing more specifically refers to a swept comb-filtering effect where there is no linear harmonic relationship between the teeth of the comb (compare this with flanging, where the teeth of the comb-filter are spaced along the frequency spectrum in a linear harmonic series).

A flanger is a subtype of phaser in which the notches are uniformly spaced. In this case, the notches are created by mixing the signal with a delayed version of a signal. Flangers tend to sound more natural, like the "jet plane whoosh" effect, whereas phasers tend to sound more unnatural.

The electronic phasing effect is created by splitting an audio signal into two, electronically shifting the phase of one signal (usually by passing it through an all-pass filter), and then recombining the two signals. The all-pass filter passes all frequencies unchanged in amplitude, but has a frequency-dependent, non-linear effect on the phase of each frequency. The result is a signal whose overall spectrum is shifted by various amounts at each frequency. For example, the phase of a frequency at the low end of the spectrum may be shifted by 1/4 of a wavelength, while a frequency at the high end of the spectrum may be shifted by 3/4 of a wavelength.

Traditional electronic phasers use a series of variable all-pass phase-shift networks which alter the phases of the different frequency components in the signal . These networks do not alter the sound themselves (human ears are not very responsive to phase differences), but they yield constructive and destructive interference when mixed back with the dry (unprocessed) signal. Additionally, the output can be fed back to the input to create a more intense effect. Most modern phasers are a part of a digital signal processor, often trying to emulate analog phasers. Phasers are mostly found as plugins for sound editing software, as a part of a monolithic rackmount sound effect unit, or as "stompbox" guitar effects.

When the filtered and non-filtered signals are recombined, the phase differences between them now cause peaks and notches of reinforcement and cancellation along the frequency spectrum (the so-called comb filter pattern). The degree of phase shift is periodically modulated (usually using an LFO), causing the peaks and notches to 'sweep' up and down the frequency spectrum, producing the characteristic rolling timbral changes of the phasing effect.

A stereo phaser is usually two identical phasers modulated by a quadrature signal; the output of the oscillators for the left and right channels are a quarter-wave out of phase.

(thanks to wikipedia )

Also: http://www.harmony-central.com/Effects/Art...Phase_Shifting/

oh great, i didn't think about that.

thank you so much

[fryovanni]

Not sure if it is exactly the same definition in an audio ckt. as in a power ckt., but in a power ckt. phase shifting refers to changing the phase relationship of voltage and current. This relates to inductive reactance or capactive reactance causing the current to lead or lag the voltage(thus shifting the relation between the two in time). In an audio circuit I am assuming you reference the original signal and a modified version(shifted) and this creates the detectable difference in sound. I am an electrician though and not an electronics guy. So I defer to the experts.

Peace,Rich

[Mr Alex]

In an audio circuit I am assuming you reference the original signal and a modified version(shifted) and this creates the detectable difference in sound. I am an electrician though and not an electronics guy. So I defer to the experts.

Peace,Rich

Never studied any "normal" phasers, but that's basically how my univibe clone works.