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Thread: Preamp/Amp Suggestion for Sierra 2

  1. #21
    Join Date
    Aug 2003
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    Manhattan Beach, California
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    6,157

    Default Re: Preamp/Amp Suggestion for Sierra 2

    Get the ATI fixed.

  2. #22
    Join Date
    Dec 2016
    Location
    Central NC
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    20

    Default Re: Preamp/Amp Suggestion for Sierra 2

    Quote Originally Posted by PoppaOptic View Post
    Based on this it would seem the Emotiva might not be the best choice since it uses a switch mode power supply.
    No. Dave was talking about the switching noise that a class D amplifier makes, not about what kind of a power supply it has. A class D amplifier works differently from a class A/B amplifier. Class D amp is not a linear gain device like class A/B are. Class D manufactures gain through a process of rapid switching between output transistors. Basically it outputs a pulse train (pulse width, pulse density, etc. similar to the way a PWM controller can control a servo motor). The audio modulates the pulse train. The pulses themselves are "cleaned off" the signal using a low pass filter between the output of the amp and the speaker cable connector. The noise Dave is talking about occurs when the circuits switch from one side to the other in creating the pulse train. This occurs in the signal path; it's very difficult to keep all this noise out of the signal going to the speaker. As a result, if it's in the signal the speakers can reproduce it as an audible artifact. I'll make some people run from the room.

    The reason to use a class D amplifier is the very high efficiency. They work great in subwoofers for example, where the efficiency is really needed, and the switching noise is well beyond what the subwoofer can produce, so you can't hear it.

    A switching mode power supply OTOH, is a modern light weight high efficiency (less waste heat so less need of noisy fans) power supply that converts the AC power from your wall plug to the various DC power rails that the amplifier needs to function. While it works somewhat similarly to the class D amp, what it is doing is not directly in the signal path, so in a properly designed amplifier it does not cause audible artifacts.
    "If it sounds good, it is good." -- Duke Ellington

  3. #23
    Join Date
    Aug 2003
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    USA
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    3,564

    Default Re: Preamp/Amp Suggestion for Sierra 2

    Quote Originally Posted by Bruce Watson View Post
    No. Dave was talking about the switching noise that a class D amplifier makes, not about what kind of a power supply it has. A class D amplifier works differently from a class A/B amplifier. Class D amp is not a linear gain device like class A/B are. Class D manufactures gain through a process of rapid switching between output transistors. Basically it outputs a pulse train (pulse width, pulse density, etc. similar to the way a PWM controller can control a servo motor). The audio modulates the pulse train. The pulses themselves are "cleaned off" the signal using a low pass filter between the output of the amp and the speaker cable connector. The noise Dave is talking about occurs when the circuits switch from one side to the other in creating the pulse train. This occurs in the signal path; it's very difficult to keep all this noise out of the signal going to the speaker. As a result, if it's in the signal the speakers can reproduce it as an audible artifact. I'll make some people run from the room.

    The reason to use a class D amplifier is the very high efficiency. They work great in subwoofers for example, where the efficiency is really needed, and the switching noise is well beyond what the subwoofer can produce, so you can't hear it.

    A switching mode power supply OTOH, is a modern light weight high efficiency (less waste heat so less need of noisy fans) power supply that converts the AC power from your wall plug to the various DC power rails that the amplifier needs to function. While it works somewhat similarly to the class D amp, what it is doing is not directly in the signal path, so in a properly designed amplifier it does not cause audible artifacts.
    Excellent post and 100% correct!!! Thanks!
    .
    .
    .
    Good Sound To You!

    David Fabrikant
    www.ascendacoustics.com

  4. #24
    Join Date
    Dec 2012
    Posts
    143

    Default Re: Preamp/Amp Suggestion for Sierra 2

    I've used class D amps, and I've never had issues (and I have fantastic hearing on audiometric testing despite my mid-40's age). It's the design of the class D that matters.

    Currently, a meager 35WPC Marantz HD-AMP1 (class-D integrated amp with fabulous DAC) is driving my Sierra-2's working as near field monitors on the computer but even at 1/4 power, the sound fills my office.
    Last edited by bkdc; 10-13-2017 at 03:23 PM.

  5. #25
    Join Date
    Jun 2016
    Location
    New Hampshire
    Posts
    16

    Default Re: Preamp/Amp Suggestion for Sierra 2

    Quote Originally Posted by Bruce Watson View Post
    No. Dave was talking about the switching noise that a class D amplifier makes, not about what kind of a power supply it has. A class D amplifier works differently from a class A/B amplifier. Class D amp is not a linear gain device like class A/B are. Class D manufactures gain through a process of rapid switching between output transistors. Basically it outputs a pulse train (pulse width, pulse density, etc. similar to the way a PWM controller can control a servo motor). The audio modulates the pulse train. The pulses themselves are "cleaned off" the signal using a low pass filter between the output of the amp and the speaker cable connector. The noise Dave is talking about occurs when the circuits switch from one side to the other in creating the pulse train. This occurs in the signal path; it's very difficult to keep all this noise out of the signal going to the speaker. As a result, if it's in the signal the speakers can reproduce it as an audible artifact. I'll make some people run from the room.

    The reason to use a class D amplifier is the very high efficiency. They work great in subwoofers for example, where the efficiency is really needed, and the switching noise is well beyond what the subwoofer can produce, so you can't hear it.

    A switching mode power supply OTOH, is a modern light weight high efficiency (less waste heat so less need of noisy fans) power supply that converts the AC power from your wall plug to the various DC power rails that the amplifier needs to function. While it works somewhat similarly to the class D amp, what it is doing is not directly in the signal path, so in a properly designed amplifier it does not cause audible artifacts.
    Thanks for the explanation!

  6. #26
    Join Date
    Dec 2016
    Posts
    8

    Default Re: Preamp/Amp Suggestion for Sierra 2

    Class D amps have gained a lot of traction in recent years in automotive applications because their advantages in power efficiency and small size factor are more important in car / ATV / motorcycle / boat installations. At the same time, due to the comparatively high ambient noise levels in those same applications, any class D inherent noise is less likely to be problematic. For example, I used a class D marine amp from JL Audio in an install for my boat a couple years ago. As music listening sometimes occured with engines off, minimal power consumed from batteries = longer music time at the sand bar without risking restart problems. It is always noisy on the water, so I never heard any amp noise above the ambient noise floor.

    Back on topic, you might consider getting a solid AVR (Marantz, Denon, Pioneer, Yamaha, etc) then determine if you want to add a dedicated amp later.

  7. #27
    Join Date
    Jun 2016
    Location
    New Hampshire
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    16

    Default Re: Preamp/Amp Suggestion for Sierra 2

    Quote Originally Posted by BrianNLS View Post
    Class D amps have gained a lot of traction in recent years in automotive applications because their advantages in power efficiency and small size factor are more important in car / ATV / motorcycle / boat installations. At the same time, due to the comparatively high ambient noise levels in those same applications, any class D inherent noise is less likely to be problematic. For example, I used a class D marine amp from JL Audio in an install for my boat a couple years ago. As music listening sometimes occured with engines off, minimal power consumed from batteries = longer music time at the sand bar without risking restart problems. It is always noisy on the water, so I never heard any amp noise above the ambient noise floor.

    Back on topic, you might consider getting a solid AVR (Marantz, Denon, Pioneer, Yamaha, etc) then determine if you want to add a dedicated amp later.

    I have a Yamaha AVR (90 WPC) and find the sound is a lot better when I add my ATI power amp. I use the ATI for the front three channels since it had a blown channel.

    Right now I want to improve on music listening rather than HT. I've been using my Yamaha as a preamp mainly. I'm leaning towards Emotiva but am also interested in Schiit, Parasound and Rotel. This assumes that I can't find a local shop to fix my ATI.

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