Phase distortion in analog gear?

Discussion in 'Software' started by towerdefense, Jul 26, 2023.

  1. towerdefense

    towerdefense Guest

    According to Slate Digital in their marketing for VBC, they "recreated the unique nonlinearities of the circuit paths" which includes "phase distortions" as separate from harmonics & transformers.
    https://slatedigital.com/virtual-buss-compressors/
    By "phase distortion", do they mean the same type of PD found in Casio CZ synths? Or something different?

     
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  3. Lieglein

    Lieglein Audiosexual

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    All of those claims are there to suggest that there would be anything special in those modules. But their phase distortion (if it is even a thing in those modules, never measured it) is not audible in the vast majority of cases.

    If it is, you can delete again because it would be horrible to have such errors in a dynamic processor.
     
    Last edited: Jul 26, 2023
  4. ᑕ⊕ֆᗰIᑢ

    ᑕ⊕ֆᗰIᑢ Platinum Record

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    Is it true to say:
    Pretty much any audio proccess like EQ or Compression will introduce changes in phase. Both in the Analog and Digital domain (except for linear-phase eqs..)??

    Yes, it is generally true to say that most audio processing techniques, including EQ (equalization) and compression, can introduce changes in phase. However, the extent of phase alteration can vary depending on the type of processing and the specific algorithms used.

    1. Analog Domain: In the analog domain, most audio processing devices and equipment, such as analog equalizers and compressors, can introduce phase shifts. This is primarily due to the inherent characteristics of the analog circuitry involved. Passive analog EQs (e.g., RC networks) and some analog compressors may cause phase shifts, especially at certain frequencies.

    2. Digital Domain: In the digital domain, audio processing is achieved using algorithms and mathematical operations on digital audio samples. Digital EQs and compressors can also introduce phase shifts, but their behavior is determined by the algorithms they use. Non-linear-phase EQs, which are more common, introduce phase shifts that vary with frequency and are not constant across the entire audio spectrum. On the other hand, linear-phase EQs attempt to maintain a consistent phase response, but they introduce other trade-offs such as higher latency.

    3. Linear-phase EQs: As you mentioned, linear-phase EQs are designed to maintain a constant phase response across all frequencies. They achieve this by delaying certain frequency components to maintain phase linearity. However, they introduce higher latency due to the need for pre-ringing and post-ringing around the filtered regions.

    Can this Phase Shifts be a fundamental part of the Character, Tone and response/behavior of any given Audio Tool?

    Yes phase shifts can indeed be a fundamental part of the character, tone, and response/behavior of any given audio tool or processing device. The impact of phase shifts on audio signals can be both subtle and significant, and it plays a crucial role in shaping the sonic characteristics of audio equipment and effects.

    1. Equalizers: The phase response of an equalizer influences how it interacts with the frequency content of the audio signal. Different types of equalizers (analog, digital, linear-phase, minimum-phase) will have distinct phase responses, leading to variations in their tonal characteristics. Some vintage analog equalizers are sought after precisely because of their unique phase shifts that contribute to their warm and musical sound.

    2. Compressors: Compressors, especially those with sidechain filters or nonlinear release behavior, can introduce phase shifts depending on their design. These phase shifts might impact the transient response and the perceived punchiness of the compressed signal.

    3. Analog Modeling Emulations: When creating digital emulations of analog equipment, developers often include models of the original device's phase response, as it significantly contributes to the overall character and authenticity of the emulation.

    4. Microphones and Speakers: The design of microphones and speakers also involves consideration of phase characteristics. The phase response of microphones affects their off-axis coloration and directionality, while phase shifts in speaker systems can affect the perceived imaging and soundstage.

    5. Phaser, Flanger, and Chorus Effects: Audio effects like phasers, flangers, and chorus units explicitly rely on introducing controlled phase shifts to create their distinctive modulation and spatial effects.
    In many cases, engineers and producers actively exploit the phase characteristics of audio tools and effects to achieve desired artistic outcomes. For example, some engineers might use analog EQs precisely because of their phase coloration, which can add a pleasing and unique character to the audio signal.

    However, it's essential to strike a balance, as excessive or undesirable phase shifts can also lead to unintended consequences, such as phase cancellation, comb filtering, or loss of clarity and definition.

    In summary, phase shifts play a crucial role in shaping the character, tone, and response of various audio tools and effects. Engineers and producers often leverage these phase characteristics to create specific sonic signatures, but careful consideration and understanding of phase-related phenomena are necessary to avoid potential issues and achieve the desired results.

    It's essential to note that phase alterations are not always undesirable. In some cases, phase shifts introduced by processing can be used creatively or to address specific audio challenges. However, when precise phase coherence is crucial (e.g., when dealing with multi-microphone recordings or phase-sensitive audio effects), engineers may opt for linear-phase EQs or other techniques to minimize phase-related issues.

    In summary, most audio processing techniques, both in the analog and digital domains, can introduce changes in phase. Linear-phase EQs are an exception to this rule and aim to maintain a constant phase response, albeit at the expense of increased latency and other trade-offs.
     
  5. towerdefense

    towerdefense Guest

    Phase distortion =! phase shift. 2 different things
     
  6. ᑕ⊕ֆᗰIᑢ

    ᑕ⊕ֆᗰIᑢ Platinum Record

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    Is Phase distortion the same as Phase shift?

    No, phase distortion and phase shift are not the same concepts, although they both involve changes in the phase of an audio signal.

    1. Phase Shift: Phase shift refers to a constant delay or advance in the timing of different frequency components of an audio signal. When a phase shift occurs, all frequencies in the signal experience the same delay or advance, which results in a uniform shift of the waveform in the time domain. Phase shift is commonly measured in degrees or radians and is typically frequency-dependent.

      Phase shift can occur due to various factors, such as analog circuitry in audio equipment, processing algorithms in digital audio devices, or the inherent characteristics of acoustic systems like microphones, speakers, and rooms. It is a normal and expected phenomenon in many audio applications.

    2. Phase Distortion: Phase distortion, on the other hand, is a specific type of non-linear distortion that occurs when the phase response of a system is altered in a frequency-dependent manner. Unlike phase shift, phase distortion does not uniformly affect all frequencies; instead, it introduces varying amounts of phase shift at different frequencies.

      Phase distortion can result in the alteration of the shape of the waveform, leading to waveform asymmetry or changes in the harmonic content of the signal. This type of distortion is typically undesirable in most audio applications, as it can introduce unwanted artifacts and alter the timbre and clarity of the sound.
    Phase distortion is generally considered a form of non-linear distortion, while phase shift is a linear phenomenon. In audio processing and equipment design, efforts are made to minimize phase distortion and maintain linear phase responses, especially in applications where phase coherence is essential, such as in high-quality audio recording, mastering, and certain types of audio effects.

    In summary, phase shift involves a constant delay or advance of all frequencies in an audio signal, while phase distortion refers to a frequency-dependent alteration of the phase response, leading to non-linear distortion of the signal's waveform.
     
  7. clone

    clone Audiosexual

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    this plugin below has been in Logic for years. I have tried it out a few times, and never left it on anything. I am not sure why they suggest it makes something more "analog" sounding in some way where i want to hear any of it ( in a bus compressor. )


    Phase Distortion in Logic Pro for Mac
    The Phase Distortion effect is based on a modulated delay line, similar to a chorus or flanger effect (see Modulation effects overview). Unlike these effects, however, the delay time is not modulated by a low frequency oscillator (LFO) but rather by a lowpass-filtered version of the input signal itself, using an internal side chain. This means that the incoming signal modulates its own phase position.

    The input signal only passes the delay line and is not affected by any other process. The Mix parameter blends the effect signal with the original signal.


    [​IMG]
     
  8. Lieglein

    Lieglein Audiosexual

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    It is by the way not advisable at all to use this tool without fundamental knowledge about the theme, to earn fundamental knowledge. There are a lot of plain wrong things about all kind of stuff in the internet and there are lots of people that have debunked plain wrong and totally undifferentiated answers of chatgpt. I do not say that it is wrong in this case, but one really has to know how to work with this thing because otherwise it will differentiate where it is not necessary and not differentiate where it is totally necessary most of the time, because that is what people do in the internet. :yes:

    And this is the case with your first post.

    Almost everytime I communicate with it, it makes an excuse for wrong statements because of simple logical errors. So you gotta know what you are talking about and how to use it.
     
  9. thejohndoe

    thejohndoe Kapellmeister

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    They just mean the default frequency response is a bit wobbly. phase is the derivative of frequency in all cases with analog components. i wouldn't really call that a "distortion"considering it's still part of the passive elements of the circuit, but it's not incorrect to call it that. bit misleading though or hyperbolic maybe. unless the VMR stuff got a complete overhaul at the fundamental level of the DSP at some point in its lifecycle, i didn't hear anything special in regards to the modelling (the 1073 is weird sounding)
     
  10. towerdefense

    towerdefense Guest

    Kilohearts also has phase distortion. I think it sounds like ass on most material, but for actual synthesis it's genuinely my favorite method of generating harmonics. Stupid simple to use (it's just like a waveshaper) but sounds less harsh than FM yet more versatile than waveshapers.

    Yeah I mean, phase shift is as natural as it gets. Real life has phase shift. I wouldn't call a natural process like phase shift a "distortion"
    I'm not really upset by the marketing or anything; I just wanted clarification on whether analog gear naturally produced phase distortion, the kind found in Casio Synths. I'm aware they produce phase shift
     
  11. clone

    clone Audiosexual

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    Also the Virus. I have never heard this Distortion brought up about any Analog hardware. If this approach was some "secret missing ingredient" reproducing analog characteristics, that plugin in Logic would get lots more use. I've never seen anyone use the plugin, other than in YT videos about it. It would not surprise me in the least to see it quietly disappear into the hidden Legacy menu of effects in Logic.
     
  12. thejohndoe

    thejohndoe Kapellmeister

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    Best Answer
    The phase distortion in Logics plugin, and the implementation by Casio aint the same thing though.

    The Logic plugin uses a short delay or "buffer"if you like that is modulated by the integrated audio input (it's the audio input passed through a lowpass filter before being used as a modulator)which gives you Yamaha style phase modulation or as they incorrectly call it "frequency modulation"but with a more complex modulator than whatever lookup tables are used on those Yamaha line of synths

    Casio's approach is a form of amplitude windowing and amplitude modulation which causes "distortion"of the slope of waveforms. it works similar to how the triangle core oscillator works in the VCO's of the CEM3340. if you've ever used the "bend"function on a wavetable synth, that could be considered similar to what Casio's PD does on the CZ101 etc

    Analog circuits can create something called parasitic capacitance which in some cases can cause phase distortions and a more blatant example of analog phase distortions would be the wow, flutter of a cassette or R2R recorder, and intermodulation of low frequencies generated by transformer coupled circuits driven a little too hot than they'd like to be operating
     
  13. justwannadownload

    justwannadownload Audiosexual

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    Could this be they simply mean phase shift? Some analog gear has quite a phase response, I heard.
     
  14. Sinus Well

    Sinus Well Audiosexual

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    But it is.
    Phase distortion example: filter cramping
     
  15. ᑕ⊕ֆᗰIᑢ

    ᑕ⊕ֆᗰIᑢ Platinum Record

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    OK Boomer.. :rofl:

    Nah really, you seem to atribute GPT's average response to me somehow,
    when it's clearly "his" answer/s - not mine.

    Also you say the answer is Not Wrong,
    and it actually helped us all being in the same page.. So then, what's the problem?
    Still you had to give the little lecture..

    In any case I was merely tryin to clarify the topic matter, while entertaining the GPT idea,
    seeing its response (socratic style), checking it and why not.. learning from it, or at least refreshing ideas related to the topic.

    I don't see the need to complain :wink:
     
    Last edited: Jul 27, 2023
  16. Lieglein

    Lieglein Audiosexual

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    That the answer is not differentiated. As I stated. :shalom:
    "Can introduce phase shifts". When and when and in how far are they audible? :dunno:

    I just wanted to clear that up that maybe some people do not fall into athis fallacy that it would be that easy with using this tool. :yes:
    Fresh ideas are only useful if you are able to evaluate them. :bleh:

    By the way, it is important to understand that these terms were created by people who psychologically and according to their outward appearance, are stuck in puberty. :suicide:
     
    Last edited: Jul 28, 2023
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