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Class A headphone amplifier

liseczq 10056 105
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  • #91
    HD-VIDEO
    Level 40  
    In the basic version of the class D amplifier there are no A / C processors but the output filter is important
  • #92
    popiol667
    Level 17  
    michald wrote:
    Tell your children about your bedtime stories.


    Take part in the blind ABX test, select the amplifier correctly and then write out that someone is telling fairy tales. A CodeBoy colleague relies on scientific research, not pseudo-scientific opinions.

    michald wrote:
    In class D, the sound is "created" and the quality depends on the A / C processors, power supplies and smoother filter. In class A, analog sound - the whole waveform is amplified simultaneously. You made a mistake with the AB class.


    Nonsense. In class A, AB the sound quality is also influenced by "Power supplies and smoothing filters". In class A, AB, the quality also depends on the reinforcement elements. Less shamanic electronics, more reading and understanding of physics, mathematics and electronics textbooks. Then it will be easier to understand the surrounding world, and not to explain it with strange theories, for example: "the entire course is strengthened simultaneously. You have mistaken the AB class". I am not writing this ironically, you have to work from scratch, sometimes go back to fundamental concepts.

    "the entire course is strengthened simultaneously." - So what, the whole three-minute song gets stronger at once? No, the signal value is amplified. Value as a function of time dependent. The function is continuous. You can't even describe correctly, express your thoughts.

    Mandatory reading, not necessarily in this order:
    1. Anatomy and physiology of hearing
    2. Sampling theorem, Nyquist-Shannon theorem + additional mathematical issues related to the topic if needed
    3. Bolton "Outline of Physics"
    4. Horowitz, Hill "The Art of Electronics"
    5. Measurement techniques
    6. A textbook for logic
  • #93
    CodeBoy
    Level 27  
    In the 20th century, people also claimed that radio waves were evil and burned the masts. Probably in class D, the cows give curdled milk :P
  • #94
    popiol667
    Level 17  
    CodeBoy wrote:
    In the 20th century, people also claimed that radio waves were evil and burned the masts. Probably in class D, the cows give curdled milk


    It is the result of a lack of knowledge. Primary.
  • #95
    CodeBoy
    Level 27  
    popiol667 wrote:
    CodeBoy wrote:
    In the 20th century, people also claimed that radio waves were evil and burned the masts. Probably in class D, the cows give curdled milk


    It is simply the result of a lack of knowledge. Primary.


    https://www.youtube.com/watch?v=MkqmZeCm31Y
  • #96
    Fimek
    Level 14  
    CodeBoy wrote:
    popiol667 wrote:
    CodeBoy wrote:
    In the 20th century, people also claimed that radio waves were evil and burned the masts. Probably in class D, the cows give curdled milk


    It is simply the result of a lack of knowledge. Primary.


    https://www.youtube.com/watch?v=MkqmZeCm31Y


    And how, it can't play well, because it's class D and it is obvious that class D can't play well, because it doesn't amplify the whole signal at the same time. In addition, it is a digital amplifier, not an analog one, that is, it dirty the sound and interferes with it. And so on.... ;)

    And now seriously - I do not understand the statement from the above film that guitars are not "played with the world, with such commitment" ... I just do not know what it means and I think that the author of the film had to add his 3 cents to the description of the sound, while when there was nothing to add, because the amplifier is completely transparent in sound and exemplary. Well, but if I'm wrong, please correct it. Plus, apart from the impressive engineering, it's just really pretty :)
  • #97
    mycodename47
    Level 14  
    Fimek wrote:
    "played with the world, with such commitment" ... I just do not know what it means and I think that the author of the film had to add his 3 cents to the description of the sound


    The point is that music is dealt with more emotionally than with physical quantities measured in a standardized way. With the sound played electronically, it is impossible to reproduce 100% what we would hear live. What we hear is influenced, among others, by the sound source, amplifier, speakers / headphones, how a given person hears and many, many other things. The fact that the amplifier is completely transparent does not necessarily mean that the sound is pleasant to listen to, it is the individual feelings of the person who is listening to the audio system. Similarly with reviews of other things, imagine that someone describes you the color of the car they like very much, they will not give RGB values, but will use words like: deep, warm, bloody, etc.

    As for the discussion, which class is better A, AB or D, according to I shouldn't be told that this one is better than the "because so and now". However, it would be decisive to compare the specific two models of amplifiers from different classes and then describe the differences between them and this does not mean that if class AB performs better than D from these two, then any other D is bad.
  • #98
    popiol667
    Level 17  
    mycodename47 wrote:
    Similarly with reviews of other things, imagine that someone describes you the color of the car they like very much, they will not give RGB values, but will use words like: deep, warm, bloody, etc.


    The point is that if you paint the same paint on the Ferrari and the Toddler, the one on the Ferrari will seem prettier than the one on the Toddler. It will be deeper, bloodier, and so on. You will stop seeing the differences when you compare only a part of the car body without knowing which car it belongs to. Similarly, you will hear colossal differences knowing which amplifier is playing and you will stop hearing without knowing which one is currently in use.
  • #99
    mycodename47
    Level 14  
    Heh ... There is something to it, human nature will subconsciously choose Ferrari as a prettier color. But coming back to audio, if, on a blind test for a given person, both amplifiers sound identical, of course it is wiser to take the cheaper one (if the appearance and other aspects are negligible). However, I do not agree with the fragment of my colleague's statement:
    Fimek wrote:
    because the amplifier is completely transparent in sound and exemplary

    I suspect that most likely none of the participants in this topic listened to the device from the YT link, I certainly did not. But I know that each amplifier "adds" and "subtracts" something from itself, there is no such thing as complete transparency and modeling. Among other things, this subtraction and addition affects the emotions I wrote about, how we hear instruments, vocals and other things in the track we are listening to. It is not real that any amplifier in the world would not distort the sound played in the entire range of work. It is often even so that people like distorted sound more, an example here are designs built on tubes, i.e. additional even and odd harmonics, or softer, sloppy bass compared to the end of power on transistors, which is caused by a transformer with a fairly high impedance on the secondary winding of the output transformer (that is why the loudspeakers for these amplifiers usually have an impedance greater than 4 or 8 Ohm). If you listen to the same track on any tube amplifier and then on a class amplifier, for example, A, B, AB, D and in a blind test, you do not see a difference, then according to me, the listener has hearing difficulties. And I am sure that there will be supporters of "hard", "clean", less distorted Class D sound, as well as those who prefer tube sound.
    Even if we take two different amplifiers of different classes, but not tube amplifiers with very similar parameters (measured in a standardized way), it does not mean that they will sound the same, full stop. Whether the blind test docker will hear the difference is another matter. I know that the differences can often be heard.
  • popiol667
    Level 17  
    mycodename47 wrote:
    But I know that each amplifier "adds" and "subtracts" something from itself, there is no such thing as complete transparency and modeling.


    OK, how do you know that? From own experience? And wasn't this experience disturbed by auto-suggestion?
  • Fimek
    Level 14  
    mycodename47 wrote:
    Fimek wrote:
    "played with the world, with such commitment" ... I just do not know what it means and I think that the author of the film had to add his 3 cents to the description of the sound


    The point is that music is dealt with more emotionally than with physical quantities measured in a standardized way. With the sound played electronically, it is impossible to reproduce 100% what we would hear live. What we hear is influenced, among others, by the sound source, amplifier, speakers / headphones, how a given person hears and many, many other things.


    But I do not negate the influence of the loudspeakers or the psophometric characteristics (I think it is called) of our ear, i.e. different subjective perception of music depending on the volume. But I mean only a power amplifier, which is, in principle, a primitive device (not this one - here's a nice engineering), with very good parameters in relation to our hearing aid, provided that someone has not screwed up something. Putting an amplifier, speakers and a human ear into one sack is a mixture of completely different domains. I just think the power amp "doesn't sound" :) unlike, for example, columns or a room.

    However, not referring to your statement, but referring to the topic in general - class D can actually play poorly, but this is not a matter of the principle of operation, but of implementation. As far as I know, the source of distortion in real systems is an incorrectly taken signal for the feedback, i.e. not from behind the LC filter at the loudspeaker, but directly from the PWM output + RC filter, or when the amplifier works without negative feedback at all, and unfortunately they have cheap amplifiers. Moreover, when the upper and lower key engagement dead zone is large, then something like cross-distortion appears and it sounds bad. But let's not mix high-class amplifiers with 2x20W pimp in the mini-tower and let's not generalize by pouring swill on the poor class D :)
  • mycodename47
    Level 14  
    I design high-end audio devices on a daily basis and I managed to convince myself that the amplifier does sound. You can find out about it in any electro market on inexpensive ONKYO, DENON etc. masks. Approach the connected set and you will hear that despite the low price (2-3 thousand PLN) the sound is really nice (apart from the parameters given by the manufacturer). Then press the button "Pure Audio" and you will hear how "average" this amplifier sounds. On average, in quotation marks, because you will feel that there is less bass and that you have to listen to the treble to hear the details, and in fact, everything that can contribute to the signal is omitted in the audio path. Other manufacturers also use such tricks. In class D, for example, decent DSP often has a positive influence.

    As for the second part of your statement, I agree, I even tried to convey the same in previous posts. Some time ago, my employer gave me the power end in class D for several thousand zlotys to play and test. and I listened to it a bit. I think he plays very well. I was just comparing it with the ONKYO apliter (AB class) and I guarantee that in blind tests I would recognize which one is currently playing. For example, after the bass, in the ending in class D, the first impression is that there is less of it, but after a few replacements of the amplifiers, you can clearly hear that in class D it is more detailed, hard, I do not know how to describe it in words, you have to hear it , perhaps this is due to the fact that class D has a very low output impedance, which makes it better control the voice coil of the low-tone speaker. Then, after connecting a DIY tube amp, it turns out that the sound is "nicer", "warmer". In all three options, the trumpet or guitar sounds different and you can really hear it. It's hard for me to say where is the best because I would also need a guy with a trumpet and a guitar. :)
  • Fimek
    Level 14  
    @ mycodename47
    Thank you for your answer. Your honest and calm tone of expression sounds very good, but my doubts remain :) My equipment is turned off, because ... because it is, and because the purchase of speakers and headphones that I have was preceded by searches and also a few disappointments, and the equipment that I use now satisfies me without assistance. It doesn't mean that they are particularly high-class, it just means that I like their sound. However, it was not, the amplifiers are not related to the principle of operation of the amplifier. On the other hand, regarding the low output impedance ... yes - class D has it by definition, but on the other hand most of the work still does the negative feedback present in modern amplifiers, regardless of the class. Maybe ... it would be worthwhile for you to do such an honest, honest test - a blank test - and let the electrode know what came out?

    Regards,
    Fimek
  • mycodename47
    Level 14  
    My point is that there is no amplifier that multiplies the input signal by GAIN and that's it. There are always distortions, in some devices smaller, in others larger, sometimes pleasant, indifferent or bothersome.

    As for the negative feedback, which in addition to increasing the bandwidth of the amplifier, reducing non-linear distortions, lowering the output impedance and other advantages, causes a change in the input signal. When you measure the distortions for e.g. 1khz, 2khz, 7khz, 12khz and you get very good results, so ultra-low distortions, it turns out that when the amplifier receives these signals at one moment, it will turn out that each frequency will shift in phase differently, resulting in the sound, apart from amplification, may be strongly distorted. Manufacturers often boast about such measurements, where they show perfect fringes in the spectrum, sometimes even averaged over time, unfortunately these beautiful charts do not show phase distortions. This is where the different-sounding trumpet and guitar come from.

    I recommend interesting articles, supported by measurements:
    Link
    Link see Figures 3.4.6 and 3.4.7

    Sometimes it is even so that the amplifiers start to oscillate outside the acoustic band, which is usually not audible, but it causes strong heating of the semiconductors. The simplest solution is to add a small capacity in the feedback loop, which also affects the phase distortions.
  • yogi009
    Level 43  
    popiol667 wrote:
    The point is that if you paint the same paint on the Ferrari and the Toddler, the one on the Ferrari will seem prettier than the one on the Toddler. It will be deeper, bloodier, and so on. You will stop seeing the differences when you compare only a part of the car body without knowing which car it belongs to. Similarly, you will hear colossal differences knowing which amplifier is playing and you will stop hearing without knowing which one is currently in use.


    Likewise, if you paint a toddler with Ferrari paint, a toddler D-Class will not fart from the exhaust like a Ferrari. So much for the topic.

    Added after 2 [minutes]:

    mycodename47 wrote:
    In class D, for example, decent DSP often has a positive influence.


    Read: "changes the color closer to the desired quality".

    Added after 7 [minutes]:

    The sound is a bit like modern photos made for sale by professionals. Before they are offered, they are treated with post-burn agents. The skin of the models is edited, contrasts and colors are enhanced, etc. Unfortunately, the same applies to music. All you have to do is compare the concerts recorded by a sound engineer for the studio, radio and TV. The latter is practically not suitable as a source for creating a demo, the characteristics of TV signals simply have different requirements. Going back to class D and the rightly mentioned DSP, nowadays it is cheaper and easier to assemble such a set and digitally simulate the desired colors at the output. Hardly anyone can distinguish it, but still it is possible. And most of all, this sound is not real. It is enough to listen to good recordings from the Chopin Competition or the best jazz tracks. Then you know whether the recording "breathes" or whether it is driving with lofty bands and dynamics.
  • popiol667
    Level 17  
    yogi009 wrote:
    Likewise, if you paint a toddler with Ferrari paint, a toddler D-Class will not fart from the exhaust like a Ferrari. So much for the topic.


    In fact, until you perform the tests on the dynamometer, you do not know what the real parameters of the engine are and what someone put under the hood ...

    yogi009 wrote:
    Read: "changes the color closer to the desired quality".


    The feedback in the analog amplifier can also be said to "change the timbre closer to the desired quality".
    DSP is there to adjust the parameters of the amplifier to the signal, so as to reproduce the signal as faithfully as possible, not to change it.

    DSP - why not (of course I do not mean indulgence functions from cheap towers), if it will improve the sound quality. It opens up possibilities unavailable for analog technology, e.g. correction of phase shifts of a loudspeaker, suppression of loudspeaker resonances, etc.