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Tuesday, October 9, 2018

Baja AC30TB Emulator

Another one of Bajaman's many amp emulator circuits. It emulates the frequency response of the classic Vox AC30 top boost channel, including power amplifier emulation. It's designed to fit in a 125B with top mounted jacks. Schematic and discussion on FSB here.

The input buffer stage uses a 2SK117 JFET with DGS pinout, but I've throw in an extra pad to use JFETs with GSD pinout (J201, 2N5457, etc). If you're using the 2SK117 you won't need to populate the jumper by Q1, but if you're using a GSD pinout transistor, you will need that jumper.

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16 comments:

  1. BerkicauOctober 9, 2018 at 10:23 AM

    What are those CBE pinned-out trannies?

    ReplyDelete
    Replies
    1. Effects LayoutsOctober 9, 2018 at 11:54 AM

      Oh, those are BC547B transistors. Other low-mid gain transistors should work, as they're just being used as clipping diodes.

      Delete
  2. Nick JamesOctober 9, 2018 at 2:19 PM

    Brilliant. Are you going to do the normal channel?

    ReplyDelete
  3. РоманOctober 9, 2018 at 2:25 PM

    see also Catalinbread Galileo

    ReplyDelete
  4. naderOctober 11, 2018 at 12:03 PM

    take a look at that (this is mkII):http://www.freestompboxes.org/viewtopic.php?f=13&t=28847

    and this: http://www.freestompboxes.org/viewtopic.php?f=13&t=28982

    Thanks, I love your layouts!

    ReplyDelete
  5. Лучше чем ничего...October 17, 2018 at 1:57 PM

    good day 2sk177 - SGD?? or DGS
    Is the schematic layout correct?
    http://rtellason.com/transdata/2sk117.pdf Thank you)

    ReplyDelete
    Replies
    1. Effects LayoutsOctober 17, 2018 at 2:00 PM

      2SK117 is DGS

      Delete
    2. Лучше чем ничего...October 17, 2018 at 2:25 PM

      on the diagram: 1 - S; 2 - G; 3 - D.
      datasheet : 1 - D; 2 - G; 3 - S.
      should it be turned the other way around?
      Sorry for my English

      Delete
    3. Effects LayoutsOctober 17, 2018 at 3:24 PM

      I think the data sheet is showing the under side of the transistor, but I could be wrong. Use a socket just in case :D

      Delete
    4. Лучше чем ничего...October 17, 2018 at 5:12 PM

      thank you)

      Delete
    5. Fever van RoodeMarch 24, 2019 at 11:05 PM

      Please note that 2SK117 are Drain, Gate, Source. The layout shows the transistor backwards. The flat side is on the left. Check out this diagram for how the pins are laid out. http://www.freestompboxes.org/download/file.php?id=1096

      Delete
  6. bcruzin2October 18, 2018 at 9:10 PM

    Built this and sounds great. I did socket the transistors and prefer the sound without the clipping transistors. I did also try mini red LEDs and bc170s, each have their own qualities, probably going to add a switch to select what suits my mood.

    ReplyDelete
  7. ZZOYDOctober 29, 2018 at 5:30 AM

    I like it without transistors too!

    ReplyDelete