Advertisement



  1. Things you need to know about the new ‘Conversations’ PM system:

    a) DO NOT REPLY TO THE NOTIFICATION EMAIL! I get them, not the intended recipient. I get a lot of them and I do not want them! It is just a notification, log into the site and reply from there.

    b) To delete old conversations use the ‘Leave conversation’ option. This is just delete by another name.
    Dismiss Notice

Who's Heard the Dutch & Dutch Speakers

Discussion in 'audio' started by zekezebra, Nov 27, 2018.

Thread Status:
Not open for further replies.
  1. Strictly Stereo

    Strictly Stereo Trade: Strictly Stereo

    Nagraboy and Emlin like this.
  2. Emlin

    Emlin MQA Hater!

    In this way:

    The term "class D" is sometimes misunderstood as meaning a "digital" amplifier. While some class-D amps may indeed be controlled by digital circuits or include digital signal processing devices, the power stage deals with voltage and current as a function of non-quantized time. The smallest amount of noise, timing uncertainty, voltage ripple or any other non-ideality immediately results in an irreversible change of the output signal. The same errors in a digital system will only lead to incorrect results when they become so large that a signal representing a digit is distorted beyond recognition. Up to that point, non-idealities have no impact on the transmitted signal. Generally, digital signals are quantized in both amplitude and wavelength, while analog signals are quantized in one (e.g. PWM) or (usually) neither quantity.
     
  3. Switching speed[edit]
    Two significant design challenges for MOSFET driver circuits in class-D amplifiers are keeping dead times and linear mode operation as short as possible. "Dead time" is the period during a switching transition when both output MOSFETs are driven into Cut-Off Mode and both are "off". Dead times need to be as short as possible to maintain an accurate low-distortion output signal, but dead times that are too short cause the MOSFET that is switching on to start conducting before the MOSFET that is switching off has stopped conducting. The MOSFETs effectively short the output power supply through themselves in a condition known as "shoot-through". Meanwhile, the MOSFET drivers also need to drive the MOSFETs between switching states as fast as possible to minimize the amount of time a MOSFET is in Linear Mode—the state between Cut-Off Mode and Saturation Mode where the MOSFET is neither fully on nor fully off and conducts current with a significant resistance, creating significant heat. Driver failures that allow shoot-through and/or too much linear mode operation result in excessive losses and sometimes catastrophic failure of the MOSFETs.[4] There are also problems with using PWM for the modulator; as the audio level approaches 100%, the pulse width can get so narrow as to challenge the ability of the driver circuit and the MOSFET to respond. These pulses can get down to just a few nanoseconds and can result in the above undesired conditions of shoot-through and/or Linear mode. This is why other modulation techniques such as Pulse Density can get closer to the theoretical 100% efficiency than PWM.
     
  4. Andrew C!

    Andrew C! Been around a while....

    Personally I’m not fussed too much re the type of amp. Get me... being a bit of a rebel. However, I do want them to sound good.
     
  5. Strictly Stereo

    Strictly Stereo Trade: Strictly Stereo

    This is a good video and it makes a nice antidote to the “let’s smash up a perfectly good Devialet Phantom” video that I had the misfortune to watch earlier today.
     
  6. Strictly Stereo

    Strictly Stereo Trade: Strictly Stereo

    What is your point?
     
    Emlin likes this.
  7. It’s a shame they didn’t use linear amplification, given the size of the cabs and the 10k asking price
     
  8. Purité Audio

    Purité Audio Trade: Purite Audio

    Perhaps they could have asked Audionet, oh wait..
    Keith
     
    Emlin likes this.
  9. Perhaps they will, sooner than you think
     
  10. Strictly Stereo

    Strictly Stereo Trade: Strictly Stereo

    Why? Other amplifier topologies come with their own design challenges.

    Listening to a pair would quickly settle any doubts about the suitability or quality of the amplifiers used inside the 8c.
     
    Cereal Killer likes this.
  11. Nagraboy

    Nagraboy pfm Member

    From the Wiki article you posted:

    The term "class D" is sometimes misunderstood as meaning a "digital" amplifier. While some class-D amps may indeed be controlled by digital circuits or include digital signal processing devices, the power stage deals with voltage and current as a function of non-quantized time. The smallest amount of noise, timing uncertainty, voltage ripple or any other non-ideality immediately results in an irreversible change of the output signal. The same errors in a digital system will only lead to incorrect results when they become so large that a signal representing a digit is distorted beyond recognition. Up to that point, non-idealities have no impact on the transmitted signal. Generally, digital signals are quantized in both amplitude and wavelength, while analog signals are quantized in one (e.g. PWM) or (usually) neither quantity.

    The Dutch & Dutch 8c are fantastic speakers. Banging on about the ways they contravene some people’s audio ideology is pretty silly, when they are so good.
     
    Emlin likes this.
  12. Still it’s a microprocessor controlled amp, a chip amp
     
  13. Nagraboy

    Nagraboy pfm Member

    Is it? Good heavens. Might as well bin them now then :D

    I think the term ‘cutting off your nose to spite your face’ might be pertinent here.
     
    Emlin likes this.
  14. Emlin

    Emlin MQA Hater!

    They've got these new fangled transistor thingies. They'll never catch on.
     
    Matthijs van Duin likes this.
  15. firedog

    firedog pfm Member

    Quote from your link:
    "The term "class D" is sometimes misunderstood as meaning a "digital" amplifier."

    It's an argument. The facts on the side of calling it analog basically are: a) it doesn't operate based on "bits" and doesn't need a reconstruction filter to output sound; b) direct output (without filter) from a class D amp can be sent to speakers over analog connection and you get sound/music. Yes, it is noisy, but it is sound. If it wasn't essentially analog you could not do this. As you can't with an actual digital signal.
     
  16. firedog

    firedog pfm Member

    Nothing here actually says digital. As mentioned, the above can be understood as a different method of analog.
     
  17. The are micro-processor controlled amps with filters, they are not pure analog amps. Yes, some have MOSFETs doesn't make them analog amps.

    Terminology[edit]
    The term "class D" is sometimes misunderstood as meaning a "digital" amplifier. While some class-D amps may indeed be controlled by digital circuits or include digital signal processing devices, the power stage deals with voltage and current as a function of non-quantized time. The smallest amount of noise, timing uncertainty, voltage ripple or any other non-ideality immediately results in an irreversible change of the output signal. The same errors in a digital system will only lead to incorrect results when they become so large that a signal representing a digit is distorted beyond recognition. Up to that point, non-idealities have no impact on the transmitted signal. Generally, digital signals are quantized in both amplitude and wavelength, while analog signals are quantized in one (e.g. PWM) or (usually) neither quantity.
     
  18. SteveH

    SteveH pfm Member

    Have you heard them?
     
Thread Status:
Not open for further replies.

Share This Page





Advertisement


  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.
    Dismiss Notice