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DOD FX72 Flanger Speed

Discussion in 'Effects [BG]' started by jd_watt, Mar 14, 2021.


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  1. Mar 14, 2021 #1
    jd_watt

    jd_watt

    Mar 22, 2013
    Hi, all! I recently won a DOD FX72 Bass Flanger on eBay for a very affordable $30. It's a flexible, great sounding flanger, but I have a question on its speed function:

    The manual states the speed sweep is .8 - 8hz which doesn't mean much to me. I've noticed that the sweep doesn't begin to move until the knob is around 9 o'clock, and it maxes out at a rate that I'd consider "moderate" for most modulation pedals. Basically, there's no chance of getting faster rotary sounds out of the unit.

    Is this aspect of the pedal faulty?

    I know there are a few internal trim pots, but my searches haven't indicated that they are related to speed. It sounds like they may be tied to width, delay, and regen.

    Although it's a different unit, you can hear how fast the FX75 B gets in this clip around the 10 minute mark.



    Although they're obviously two different effects, they share the same manual, so it seems like some, if not most, of their functionality should be the same.

    Thanks as always for having a look. Any input is appreciated!
     
  5. Mar 14, 2021 #2
    Peaveylover

    Peaveylover Inactive Supporting Member

    Dec 6, 2019
    Normal for the FX 72. I can make a demo later of the sweep range in case you want to hear mine.
     
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  9. Mar 14, 2021 #3
    jd_watt

    jd_watt

    Mar 22, 2013
    Hey, thanks for the reply! A demo would be awesome, if you have the time. I'm just working through the tones to see what works best for me. I'm using a p bass and looking for some subtler (less metallic) post punk-inspired tones. Thanks for the offer!
     
    Peaveylover likes this.
  13. Mar 14, 2021 #4
    Peaveylover

    Peaveylover Inactive Supporting Member

    Dec 6, 2019
    No probs. I love my FX72B. One of the best flangers in the world for bass. I have a p bass too so it should sound pretty similar. I'm just going to focus on speed though since that's your main concern. Should get to it later today.
     
    jd_watt likes this.
  18. Mar 14, 2021 #5
    Peaveylover

    Peaveylover Inactive Supporting Member

    Dec 6, 2019
    @jd_watt Here you go buddy. Just some noodling, and it's pretty clear when I ramp up speed to max. P bass into FX72 into MOTU M2 direct.
     
    Last edited: Mar 14, 2021
    Clark W, jd_watt and DJ Bebop like this.
  22. Mar 14, 2021 #6
    Feral Feline

    Feral Feline

    Jan 23, 2007
    Honky Kong, ShangriLamma
    Great sounding pedal, @Peaveylover , many thanks for posting that.
     
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  26. Mar 14, 2021 #7
    Peaveylover

    Peaveylover Inactive Supporting Member

    Dec 6, 2019
    No probs Feral
     
  30. Mar 14, 2021 #8
    jd_watt

    jd_watt

    Mar 22, 2013
    Definitely a big thank you for posting that, Peavylover! No doubt there's something wrong with my pedal. I can't come close to getting my speed up that fast with my flanger. You're almost twice as fast as mine with the speed maxed... and I've tried all combinations of setting. WOW... what gives!?!?!
     
    Peaveylover likes this.
  34. Mar 14, 2021 #9
    Peaveylover

    Peaveylover Inactive Supporting Member

    Dec 6, 2019
    No probs. My pleasure. Sounds like you may have an issue for sure. That sucks! I have no idea what might be wrong. Might not be worth even trying to fix. Probably cheaper to get another one. Mine came mint in the original box with all papers and catalogs. I paid $70.
     
  38. Mar 14, 2021 #10
    jd_watt

    jd_watt

    Mar 22, 2013
    True... It was kinda an impulse buy. I read some pretty favorable things about it, and grabbed one for $30, as mentioned. Still, after shipping +tax, it would be cool to have a fully functional pedal. It definitely sounds good!
     
    Peaveylover likes this.
  42. Mar 14, 2021 #11
    Peaveylover

    Peaveylover Inactive Supporting Member

    Dec 6, 2019
    True. I think it's definitely worth picking up another one though. It really is one of the best flangers for bass IMO and totally underlooked by the cork sniffers.
     
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  47. Mar 14, 2021 #12
    jd_watt

    jd_watt

    Mar 22, 2013
    Thank you for all your help, Peaveylover. I'll hope to hear if anyone has any other thoughts or suggestions for further testing.
     
  51. Mar 14, 2021 #13
    xJasonSmithx

    xJasonSmithx Supporting Member

    Jun 25, 2003
    Denver, CO
    The bass version definitely sounds a lot different than the FX75-B. I really regret selling my FX72. Let me know if you want to get rid of it @jd_watt .
     
    jd_watt likes this.
  55. Mar 14, 2021 #14
    Feral Feline

    Feral Feline

    Jan 23, 2007
    Honky Kong, ShangriLamma
    Faulty. Speed.

    I don't know enough yet to even guess what's wrong with it, but... Could be corroded pot, could be old caps, old faulty solder joints... Now I'm really curious. @Wasnex might be able to help.
     
    jd_watt likes this.
  59. Mar 14, 2021 #15
    Wasnex

    Wasnex

    Dec 25, 2011

    Hard to say without a schematic. Could be a component has drifted out of spec or someone screw with an internal trim pot that is not intended for user adjustment.

    Sometimes messing with the internal controls can nasty gremlins into a device that are difficult to impossible to remove without following the factory setup procedure...sometimes adjusting one of these controls can cause a major meltdown :eek:--in other words, the magic smoke get's out :bawl:.
     
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  63. Mar 14, 2021 #16
    jd_watt

    jd_watt

    Mar 22, 2013
    I'd love to get in there with a soldering gun, but like you Feral Feline, I'm just not sure what's happening here. I'm not very experienced in reading schematics, but I'd be willing to try (haven't found one yet). I took it apart and had a look around. Nothing looked fried or out of place. Again, I know that doesn't tell us much!
     
  67. Mar 14, 2021 #17
    Wasnex

    Wasnex

    Dec 25, 2011
    I Googled FX72 and I found a schematic for the FX75...no idea if they are similar or not. The FX75 may have been a major update, or they may have just swapped in a better IC chip.
    dod_fx75b.gif

    I am by no means an electronics expert, but I believe the frequency is controlled primarily by P7 and C11 in the LFP circuit. It's possible other surrounding components in the LFP could have an impact on the speed as well.
     
    jd_watt likes this.
  71. Mar 14, 2021 #18
    jd_watt

    jd_watt

    Mar 22, 2013
    That's a good start, Wasnex. Maybe a few other experienced members will have some input. Thanks for sharing!
     
    Wasnex likes this.
  76. Mar 14, 2021 #19
    xJasonSmithx

    xJasonSmithx Supporting Member

    Jun 25, 2003
    Denver, CO
    Cleaning the pots with some electrical contact cleaner is usually a good place to start as well.
     
    jd_watt likes this.
  80. Mar 16, 2021 #20
    jd_watt

    jd_watt

    Mar 22, 2013
    Just checking in for anyone following: I cleaned the pot with some Dioxit, and nothing changed. I identified three internal trim pots, and from what I've read, none of them control the actual speed of the sweep. So, I'm at a bit of a loss, but the pedal is still great at moderate speeds (which is how I'd usually use the pedal anyway). Still, if anyone has any other thoughts, they'd be appreciated. Thanks!
     
    xJasonSmithx likes this.
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