what to build with 2 NKT275 ??

Discussion in 'Effects, Pedals, Strings & Things' started by JoeBob, Feb 13, 2012.

  1. JoeBob

    JoeBob Supporting Member

    Messages:
    534
    Joined:
    Jan 9, 2006
    Location:
    Montreal, Canada.
    My friend just got a couple of NKT275 from Ebay, we're kind of
    wondering what clone to build ? can you point out some ideas, schematics ??

    Thx
     
  2. Whiskey N Beans

    Whiskey N Beans Supporting Member

    Messages:
    2,604
    Joined:
    Dec 30, 2009
    Location:
    Sunset District
    Fuzz Face seems to be a tested platform for those transistors.
     
  3. Tiny Montgomery

    Tiny Montgomery Supporting Member

    Messages:
    7,174
    Joined:
    Mar 16, 2009
    Location:
    Louisville, Ky.
    Yep, a fuzz face would be the obvious choice. That's why they're famous.
     
  4. markmantle

    markmantle Member

    Messages:
    392
    Joined:
    Jun 28, 2010
    Or 2 treble boosters
     
  5. JoeBob

    JoeBob Supporting Member

    Messages:
    534
    Joined:
    Jan 9, 2006
    Location:
    Montreal, Canada.
    Gain is 81 and 121.

    Any schematic for a good FF ?
     
  6. jkokura

    jkokura Member

    Messages:
    895
    Joined:
    Sep 2, 2009
    Or you could build a Tonebender if you could find another.

    Test them for gain ranges and leakage if you can, that will help if you're looking for what spot to put them into the circuit.

    Jacob
     
  7. mmolteratx

    mmolteratx Member

    Messages:
    2,865
    Joined:
    Jul 23, 2009
    Location:
    Austin, Texas
    What are the leakages? The Hfe is perfect for a Fuzz Face. 81 in Q1, 121 in Q2. Just use any Fuzz Face schematic. I'd use a 1uF or smaller cap for the input cap though. 2u2 is too big IMO. IIRC, Analog Mike has stated he's seen a bunch of 1uFs in vintage Fuzz Faces anyways. It certainly is a nice balance between too thin and too wooly/muddy.

    Also, a better method of biasing the circuit than the trimmer on Q2 would be to keep the 8k2 collector resistor and use a 100k trimmer on the collector of Q1, i.e. the Tone Bender trick that's been floating around for a while. Also, change the 330R (or 470R depending on the schematic) resistor to 1k for more output.
     
  8. JoeBob

    JoeBob Supporting Member

    Messages:
    534
    Joined:
    Jan 9, 2006
    Location:
    Montreal, Canada.
    How to measure leakages ?
     
  9. mmolteratx

    mmolteratx Member

    Messages:
    2,865
    Joined:
    Jul 23, 2009
    Location:
    Austin, Texas
    http://www.geofex.com/Article_Folders/ffselect.htm

    This is the usual way. Though I've got a Peak DCA55 which measures it for me without having to do any math. If you're measuring any decent quantity of transistors, I highly recommend one.
     
  10. JoeBob

    JoeBob Supporting Member

    Messages:
    534
    Joined:
    Jan 9, 2006
    Location:
    Montreal, Canada.
    thx, we'll look into it !
     
  11. mmolteratx

    mmolteratx Member

    Messages:
    2,865
    Joined:
    Jul 23, 2009
    Location:
    Austin, Texas
    BTW, are they the TO-1 or the Tungsram type packaging? If the latter, I'd add a small cap (anything between 10-50pF or so) between base and collector of each transistor.
     
  12. JoeBob

    JoeBob Supporting Member

    Messages:
    534
    Joined:
    Jan 9, 2006
    Location:
    Montreal, Canada.
    Humm, dont have a clue !!
     

Share This Page