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MOS FET amps

Discussion in 'Amps and Cabs [BG]' started by mikemulcahy, Aug 31, 2000.


  1. mikemulcahy

    mikemulcahy

    Jun 13, 2000
    The Abyss
    I would like some intelligent opinions on MOS FET amps. I am considering one and have never used one.
     
  2. White_Knight

    White_Knight

    Mar 19, 2000
    USA
    Well, for starters MOSFETS are a type of transistor that switches faster than standard transistors. This means that they run a lot cooler which ultimately makes them more reliable and longer lasting.
     
    Killed_by_Death likes this.
  3. I know alot of car audio amps use Mos Fets. I don't really know if many bass amps do or not. Later!

    Woffy Out!
     
  4. There's absolutely no distinguishable difference in sound between mosfets and normal (bipolar) transistors. Mosfet are just a different type of transistor. When applied in a certain way, they are a little bit more efficient.

    The name says it all. Mosfet stands for Metal Oxide Semiconductor Field Effect Transistor. Just a transistor. No special stuff. Your computer holds millions and millions of'em .............

     
  5. Munjibunga

    Munjibunga Total Hyper-Elite Member Gold Supporting Member

    May 6, 2000
    San Diego (when not at Groom Lake)
    Independent Contractor to Bass San Diego
    Hey Joris ... don't most modern solid state power amps use MOSFETs anyway?
     
  6. True. And most brands don't put it in their specs, cause it's nothing to be bragging about, there's nothing to brag. Fortunately, real tech heads know there's no difference. A few years ago, mosfet were the latest (solid) state of the art technology. At the recent speed of developments, probably another technology like IGBT will take the lead in advertisements, or Triac, Thyristor, PWM, Class H, or whatever sounds interesing.

    (IGBT=Insulated Gate Bipolar Transistor, a combination of a mosfet and a bipolar [normal] transistor)

     
  7. Munjibunga

    Munjibunga Total Hyper-Elite Member Gold Supporting Member

    May 6, 2000
    San Diego (when not at Groom Lake)
    Independent Contractor to Bass San Diego
    Now, are these IGBT's doped with lithium?
     
    chuck3, rufus.K and jazzbass_5 like this.
  8. Wha?
     
  9. Munjibunga

    Munjibunga Total Hyper-Elite Member Gold Supporting Member

    May 6, 2000
    San Diego (when not at Groom Lake)
    Independent Contractor to Bass San Diego
    I was afraid of this ... bipolar disorder ... lithium is the medication. It was a stretch. I thought at least one person would get it. Never mind.
     
  10. Please note: I'm Dutch. Most puns are wasted on me.... Nice try though. :D:D:D
     
    Plastalmonus, Al Kraft and rufus.K like this.
  11. Reading up on the F.E.T. threads this evening. I was thinking it would be great to have a amp made with them, but it seems it's been tried & didn't really go over so well.
    Has F.E.T. use in power amps gone the way of the Dodo bird?
    or is it just so common now that no one brags about it?
     
  12. abarson

    abarson

    Nov 6, 2003
    Santa Cruz
    Dude! The thread's been dead for nearly two decades!
     
    Plastalmonus and Al Kraft like this.
  13. MOSFETs are still a thing
     
  14. TBGFRED

    TBGFRED Supporting Member

    Apr 24, 2009
    Panama City Beach, FL
    kbd
    the only amp that i can recall featuring fet/mosfet innards is the bugera veyron m bv1001.
    "The preamp is driven by classis MOSFET technology, which imparts a warmth to your tone."
    I'm recalling the amp has a small but fervent fan club here on tb ....
    let us know what important info you find
     
    Killed_by_Death likes this.
  15. rufus.K

    rufus.K

    Oct 18, 2015
    SoCal
    That is rich, Ima start using that.
     
    Al Kraft likes this.
  16. Al Kraft

    Al Kraft Supporting Member

    May 2, 2016
    Northern Virginia
    ...but the folklore and arguments will live on indefinitely! :thumbsup:
     
    BadExample likes this.
  17. fdeck

    fdeck Supporting Member Commercial User

    Mar 20, 2004
    Madison WI
    HPF Technology LLC
    Probably every Class-D power amp on the market right now uses MOSFETs as the switching elements. I believe that's true of switchmode power supplies as well. So MOSFETs are everywhere. Also, they have improved by leaps and bounds.
     
  18. StayLow

    StayLow

    Mar 14, 2008
    The hallowed Mesa WalkAbout uses "Mesa® patented Simul-State™ hybrid tube-driven MOSFET circuitry".

    For whatever reason, the amp sounds uniquely fantastic.
     
    Killed_by_Death likes this.
  19. ThisBass

    ThisBass

    Aug 29, 2012
    Germany
    A faster switching property of a device may decrease thermal losses of a distinct (power) schematic design.
    Which is (almost always) true for any switch mode (respectively pulse mode) applications.
    I don't think that transistors in class A/B amplifiers act just the same way as is for class D amplifiers.
     
  20. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa, Product Support-Genz Benz
    Switching speeds only matter in Class D amps and switchmode power supplies. Linear amps don't switch, therefore that spec doesn't apply.

    Different types of devices for different app.
     

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