Pages

▼

Thursday, July 23, 2015

DOD FX25 Envelope Filter

The FX25 was initially produced by DOD in the early 80s and is an OTA-based envelope filter/auto-wah. It's a fairly tweakable and you can find various mods on other sites, but this is for the stock layout. The original switching circuitry has been removed, so you can use true-bypass. An LM1458 is listed in the layout below, but just about any dual op-amp should work there (TL072, NE5532, JRC4558, etc.), so if you get a little distortion, try a different op-amp.



Update Aug. 10, 2016:

I've fixed the layout as per NapAlpha and Eduardo's comments below. Thanks for catching that guys. Sorry it took me so long to make the fix.
at

47 comments:

  1. nap_alfa55November 14, 2015 at 10:05 AM

    On the PCB there is no connection between C7 and R12-R13. The resistors R12 and R13 are 10K and not by 1K

    ReplyDelete
  2. wainer.said@gmail.comMarch 3, 2016 at 4:04 PM

    Hello layot ​​this work? There I gotta change ?
    Thanks

    ReplyDelete
  3. jandalesandsMay 19, 2016 at 3:03 AM

    i did this layout but no sound at all.. helpless!

    ReplyDelete
  4. jandalesandsMay 19, 2016 at 3:05 AM

    what's the reason for that?

    ReplyDelete
  5. jandalesandsMay 19, 2016 at 3:21 AM

    is there someone verified this layout here?

    ReplyDelete
  6. Eduardo GArciaAugust 8, 2016 at 1:41 AM

    nap_alfa55 was right. change 2x 1k resistors (COORDINATE H/V C-P/S and D-P/S, up 13600)by 10k and connect C-S to K-J. WORK FINE. VERIFIED!
    any mod or change for bass?

    ReplyDelete
  7. luciano gianinettoAugust 10, 2016 at 2:53 AM

    Is it verified? Thank u!

    ReplyDelete
    Replies
    1. Eduardo GArciaAugust 10, 2016 at 9:47 AM

      Yes, work fine. Remember to connect R12/R13 with C7 and change it with 10k

      Delete
  8. Effects LayoutsAugust 10, 2016 at 2:52 PM

    Sorry about the error in the original board, guys. Thanks for catching that missing connection. I've corrected it and it's good to go.

    ReplyDelete
  9. Taciano CanassaMay 21, 2017 at 12:22 PM

    Build this one with 47r ( did not found 51r). Worked for few seconds then burned de 47r twice! Any help? Thanks!

    ReplyDelete
  10. Effects LayoutsMay 21, 2017 at 2:40 PM

    Could be your power supply. Maybe use a high wattage resistor there?

    ReplyDelete
    Replies
    1. Taciano CanassaMay 22, 2017 at 11:35 PM

      Bad 1n4007 diode...short the 47r to ground. Replace it and no more resistor burn. But the effect still don't work as should be. I turn it on and it works well til' 30 to 40 secs of play then it's down. Any help???

      Delete
    2. pandalonOctober 11, 2017 at 12:42 PM

      i had this problem but i double check and had a short on my traces check your connections

      Delete
  11. DavidMauroJuly 7, 2017 at 7:17 PM

    hello. Can i use lm13700?

    ReplyDelete
  12. UnknownJuly 21, 2017 at 9:54 PM

    Put as VERIFIED! I just finished and it works very good! I made it with a LM13700 and MC1458.

    Greetings from Corrientes, Argentina!

    ReplyDelete
    Replies
    1. Effects LayoutsJuly 21, 2017 at 11:33 PM

      Excellent! Thanks

      Delete
    2. UnknownApril 3, 2018 at 5:26 PM

      genial, entonces si lo hago tal cual esta la foto en el layout va a funcionar? es que no se si al decir que lo corrigieron se ven reflejados esos cambios en la imagen

      Delete
    3. Effects LayoutsApril 4, 2018 at 9:05 AM

      Yes it should work.

      Delete
  13. jandalesandsSeptember 9, 2017 at 2:30 AM

    can i request for a dodo fx25 in a 1590A without the footswitch? thanks and more power..

    ReplyDelete
  14. ChrisOctober 5, 2017 at 4:06 AM

    Im into audio probing the circuit. From input to pin3 of ic 1458 the audio seems to be ok even for pins 1,2 and 7. For pins 5 and 6 the audio volume drops. I need to max the amps volume to hear the audio output. I tried to test the directly at the output and theres the slightest volume of audio that I can hear with amps volume maxed. The voltage for me are normal for both ic. I will try to get the exact voltage later when im free to get my hands on it again. I use LM13700.
    And can you point out the connectivity of the audio path circuit from input to output?
    Thank you

    ReplyDelete
    Replies
    1. Effects LayoutsOctober 5, 2017 at 4:09 PM

      Pin 7 is the output of the 2nd half of the opamp, so if the volume is ok out of there I would think it's ok. I'd guess the issue you're having is later in the circuit. Here's the schematic for reference:

      https://images.talkbass.com/attachments/dodfx25_sch-png.2309823/

      Delete
    2. ChrisApril 11, 2018 at 3:56 AM

      This comment has been removed by the author.

      Delete
  15. UnknownOctober 11, 2017 at 6:18 AM

    Are the potentiometers log or lin? I've also seen a picture of an original fx25 with one of the pots reading: C500K?

    ReplyDelete
    Replies
    1. Effects LayoutsOctober 11, 2017 at 9:15 AM

      The B prefix means lin. Those are what were specified in the schematic I believe. Rev. log pots may improve the sweep of the controls. YMMV.

      Delete
    2. LucasNovember 1, 2020 at 11:35 AM

      I tried 100k, 250k, 500k log and lin. It doesnt change that much at least for me ears. Maybe a doberman could tell the difference.
      Thanks for sharing

      Delete
  16. The AplikatorMarch 14, 2018 at 2:39 AM

    This might be a silly question but 4148 is 1n or 2n?

    ReplyDelete
  17. UnknownApril 2, 2018 at 9:23 PM

    es mejor el lm13600 o el lm13700?

    ReplyDelete
  18. Rizky EfansyahAugust 20, 2018 at 1:55 AM

    hello, has this layout been fixed? then where is the location of R12 & 13 and C7 I only see the value, thank you

    ReplyDelete
  19. UnknownSeptember 12, 2018 at 2:23 PM

    Alguna modificación para bajo ?

    ReplyDelete
    Replies
    1. Eduardo GArciaSeptember 12, 2018 at 3:32 PM

      si, pero no la subieron aca. es esta.
      http://tubehead123.blogspot.com/2015/01/dod-fx-25-envelope-filter-lowpass.html
      la hice con un switch on-on que conmute las salidas y suena muy muy bien

      Delete
  20. Eduardo GArciaSeptember 12, 2018 at 3:30 PM

    This comment has been removed by the author.

    ReplyDelete
  21. aptalfunkDecember 5, 2020 at 8:00 AM

    Hi! Thanks for your work. What should I do exactly about the pots numbered 2/3?

    ReplyDelete
    Replies
    1. Effects LayoutsDecember 5, 2020 at 12:04 PM

      You just connect those two lugs together and then run a wire to the corresponding pad.

      Delete
  22. Monyet GilaJanuary 5, 2021 at 8:55 PM

    hi, Can i replace diode 4001 with 4148 too?

    ReplyDelete
  23. Eduardo GArciaJanuary 6, 2021 at 10:38 AM

    This comment has been removed by the author.

    ReplyDelete
  24. UnknownApril 12, 2021 at 3:20 PM

    Hi. Have to hit strings really hard to open filter..can I change something to open it without hitting too hard?

    ReplyDelete
  25. Man of SivasJune 10, 2022 at 7:42 AM

    Hi, i really have issues connecting the potentiometers. It says 2 and 3 connect on one pin? In my count, 1 and 3 are the fixed resistance and 2 is the rotor, so ti variable resistance. So i connect one of the fixed pins and the rotor together to the same pin and the other side of the fixed resistor to the other?
    I assembled it but it does not work at all...

    ReplyDelete