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Fet, Jfet, bifet, MOSFET etc...

Discussion in 'The Stomp Box' started by Danjabellza, Aug 12, 2017.

  1. Danjabellza

    Danjabellza Tele-Holic

    855
    Sep 22, 2014
    Pahrump, nv
    Can any afficianafos explain in somewhat laymans terms what the differences are or even the meanings of these different citcuit names/titles? Common pedal examples of each circuit?

    The terms get thrown around a lot, and I know I have a few pedals of these different types, but I don't know what that is supposed to communicate to me about the particular circuit and what I should expect from it.

    It seems to me that a builder, technician, or engineer would find it fairly obvious, but to people who aren't in the electronics field, it can be confusing. To me anyway...

    Thanks in advance.
     

  2. Old Tele man

    Old Tele man Tele-Holic

    890
    May 10, 2017
    Tucson, AZ
    They're ALL from the "sand-pile" branch of the electronics tree (wink,wink)!
     
    Danjabellza likes this.

  3. Hexabuzz

    Hexabuzz Tele-Afflicted

    Dec 13, 2014
    Northeast PA
    2 other FETTs you need to know about...

    [​IMG]
    [​IMG]
     

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  5. luckett

    luckett Tele-Afflicted

    Jun 14, 2011
    .
    junction field effect transistor = JFET
    bipolar junction transistor = BJT
    metal oxide semiconductor field effect transistor = MOSFET

    Just three different kinds of transistor. They amplify. There is no magic in any of them.
     
    MilwMark likes this.

  6. Darkness

    Darkness Tele-Holic

    Age:
    49
    739
    Apr 7, 2016
    Stygian Gulf
    Yep. No magic in them at all. It's sorcery!
     

  7. Iago

    Iago Tele-Afflicted

    Sep 18, 2006
    Brazil
    These are not circuit types, but transistor types. Usually I see people throwing "fet" around when they're talking about Jfets.

    They are just one more ingredient in a circuit, there's no advantage of one over the other, as far as I am concerned. It's the sum of the whole (design, parts values) that will dictate what the circuit will sound like, although, IMHO, jfets and mosfets based OD's sound more amp-like than OP-Amp based OD's, YMMV.

    Jfet circuits: lots of amp in a box pedals like most of RunoffGroove and Wampler things. Many Catalinbread OD's too (The Formulas, DLS). Menatone amp-inspired pedals. Boss OD3 and BD2 are Jfet-based, if I'm not mistaken.

    Mosfet: Zvex Super Hard-On (AMZ mosfet booster). Catalinbread RAH.

    Some Op-Amp based circuits use jfets or mosfets as clipping diodes, like the Zendrive, among many others. I've used mosfets as clipping diodes in a DOD 250 and it sounded very good.

    There are some hybrid circuits around which use mosfet and jfet together as amplifiers... Or bjt and jfet, bjt, mosfet and jfet, etc... But that's another story, though.
     
    Obsessed and Danjabellza like this.

  8. Nickfl

    Nickfl Tele-Holic

    529
    May 24, 2016
    Florida
    Except germanium... the internet has assured me that germanium=Magic. Or is it Mojo, anyway its definitely something with a capital M.

    Wait maybe it was Money... :D
     

  9. Danjabellza

    Danjabellza Tele-Holic

    855
    Sep 22, 2014
    Pahrump, nv
    Alchemy
     
    Darkness likes this.

  10. sergiomajluf

    sergiomajluf Tele-Meister

    289
    Sep 26, 2015
    Santiago, Chile
    In my very limited experience building pedals for myself on and off for 15 years I tend to like more pedals that use JFET as a gain device. My oldest amp is a MOSFET design, which also I like a lot. BJT to my ears produce a harsh sound but that is also dependent on the clipping stage.

    Technically, JFETs behave similar to vaccume tube and that's why runoffgroove used them in all or most of their tube emulating designs.

    The BigMuff for instance use BJT transistors
     
    Danjabellza likes this.

  11. luckett

    luckett Tele-Afflicted

    Jun 14, 2011
    .
    MOSFET in amps are typically used in clean power sections using high power MOSFETs which are not really shaping the tone.

    JFETs behave very differently than vacuum tubes.
     
    Last edited: Aug 12, 2017

  12. Anode100

    Anode100 Friend of Leo's

    May 9, 2014
    Behind my beard.
    They all sound the same with the gain on full..... :D
     
    BB likes this.

  13. BB

    BB Friend of Leo's

    May 17, 2003
    Great Pacific NW
    That's why I never run the gain on full! Well, almost never!
     

  14. 4pickupguy

    4pickupguy Poster Extraordinaire

    May 12, 2013
    Fort Worth, Texas
    A Fetting tribute for sure...
     
    Hexabuzz likes this.

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