class d amplifier

Discussion in 'General Electronics Chat' started by justin77, Apr 4, 2010.

  1. justin77

    Thread Starter New Member

    Apr 3, 2010
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    How do i identify a class d amplifier from the outside appearence?
     
  2. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    A class D amplifier is a switching amplifier.
    It has a very high efficiency.
    That's why most times there are very small heatsinks needed.

    More info can be found on the amplifer pages from the EDUCYPEDIA:
    http://www.educypedia.be/electronics/amplifierclasses.htm

    Greetings,
    Bertus
     
    justin77 likes this.
  3. Electrobrains

    New Member

    Mar 27, 2010
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    I just built a class D amplifier with the TI TAS5709. What I realize with this development is, as already said, the fantastic efficiency. My small PCB has 2x 20W without any heat sink at all.

    What also characterizes this unit is that there are two inductors per channel (forming a power LP filter). Some (lazy/saving/ignorant/low power users/..) don't put the inductors on the PCB, but use the internal inductance of the loudspeaker instead. That's possible, but will cause emi (high current switching through the cable) and could even bring audible disturbance.

    Added to that, I also think that the small class D IC has more pins (48) than most "normal" amplifiers.
     
  4. beenthere

    Retired Moderator

    Apr 20, 2004
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  5. Wendy

    Moderator

    Mar 24, 2008
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    The inductors, while common, are not absolutely necessary.

    The only problem I had with that article is the broad sweeping statements, some designs are going to be better than others. I liked his proposed solutions, for really high power levels they would be a really good idea.

    The biggest argument for Class D efficiency is the lack of heat generated from reasonably high power levels. I don't think the other classes of amps even come close.
     
  6. Electrobrains

    New Member

    Mar 27, 2010
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    Interesting article.
    From the viewpoint of the "energy saver" it's probably accurate. In fact I have realized that the class D IC's in my application get warm even without any output signal. The interesting thing is that they just get a "little warmer" at full load power!

    Practically, for someone like me, designing a commercial audio system, the efficiency down at "don't-know-how-silent" doesn't matter a bit to me!
    I have to design at worst case and save money! Worst case is full power and money is saved by small size, no heat sink, few and cheap components and fast designing and manufacturing.
    If someone happens to improve the class D amp with low-rate-modulation or whatever, that's fine! It will give another sales argument!
     
  7. beenthere

    Retired Moderator

    Apr 20, 2004
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    Types of amps (tube, linear, digital) always have proponents that are almost religious in intensity. I would love to hear a blind test to see if some particular technology sounded better, somehow.
     
  8. Wendy

    Moderator

    Mar 24, 2008
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    My theory is if designed competently they would be indistinguishable from each other. After all, the goal is to reproduce a wave form exactly. The speakers probably have more effect on the reproduction.

    Audiophiles are strange, strange people to me, and they approach it much like a religion, with many items being subjective and a matter of faith.
     
  9. beenthere

    Retired Moderator

    Apr 20, 2004
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    I would tend to agree with that. That's why I'm so happy with my old Bose 901's. But there was quite a bit of difference when I rebuilt my Dynaco Stereo 400 as a Mike Leach Superamp (I recycled the transformer and humongus heat sink). The amp does make some difference.
     
  10. studiot

    AAC Fanatic!

    Nov 9, 2007
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    I have watched the population being steadily trained over the years to accept lower and lower standards for 'HiFi' sources.

    First we had 'HiFi' cassettes, then 'HiFi' CDs then 'HiFi' MP3s then 'HiFi' Digital Radio, all of which have shown a steady decrease in fidelity.
     
  11. beenthere

    Retired Moderator

    Apr 20, 2004
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    I might disagree in the area of FM radio. HD radio seems to have a significantly improved sound quality over conventional FM. This is a subjective judgment, though.

    MP3 compression has done nothing but lower the reproduction sound quality.
     
  12. studiot

    AAC Fanatic!

    Nov 9, 2007
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    In the UK, the audio quality is definitely bandwidth limited to less than for FM. There is something of a debate about this by those in the know.

    But as always the advertising machine tries to lead the masses to believe otherwise.

    With the other mentioned media, there have been marked convenience increases. This convenience has lead to adoption by Joe public.

    However DR suffers extremely poor coverage in the UK. FM has never achieved full coverage, but blind spots are generally in empty area.

    Although low lying and flat, about half the county town of Somerset cannot receive DR.
     
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