Home Forums GuitarPCB Build Support Dr. Phybes – 45/90 Mod

This topic contains 7 replies, has 3 voices, and was last updated by  Hank 1 month ago.

Viewing 8 posts - 1 through 8 (of 8 total)
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  • #6060

    Hank
    Participant

    When installing the Wilkie 45/90 mod in the Dr. Phybes, do you still populate R16 or do you omit or jumper it?

    #6065

    wilkie1
    Moderator

    R16 and the SW1 provide the feedback bypass function.  When you install my 45/90 mod, you can still use the feedback mod when in 90 mode.  In 45 mode, the feedback function is bypassed.  You may eliminate the feedback loop by removing SW1 and R16 if you wish.

    #6066

    Hank
    Participant

    Wilkie, Thanks.  Works great!

     

    Hank

    #6085

    Hank
    Participant

    Okay, so the build is all together but I’m getting a loud pop when engaging the foot switch if SW1 is in the on (script mod) position. The SW1 and phase 45/90 switches are both popping if switched when the phaser is engaged. All ground are good and tight. Any ideas regarding how to get rid of the pops?

    Thanks, Hank

    #6086

    wilkie1
    Moderator

    I always follow the general rule NEVER to activate any switch that carries signal during a performance.  The reason is there may be a different voltage potential on one side of the switch compared to the other side.  When the switch is activated this voltage surges and creates the pop. The foot switch is usually protected by the !M resistor at the beginning of the circuit which bleeds off this voltage.  If you still have popping from the foot switch, it mat be mechanical noise from the switch itself.

    #6087

    Hank
    Participant

    Wilkie, Thanks. The pull down resistor is a hefty 3M9 which I thought might get the pop out. I did use the older build doc that called for 22K at R16 instead of the 33K in the newer docs. Wonder if the feedback loop is too hot with 22K…?  I’m not worried about the toggles as you said. I would never try to change them on the fly but the foot switch can be problematic.

    Thanks

    hank

    #6444

    robb
    Participant

    i’ve noticed 2 different schematics for R16

    what is the difference between using a 33k and a 22k?

    thank you for your help!!

    #6446

    Hank
    Participant

    I believe 33K reduces the amount of distorton when using the Scipt mode.  Someone please correct  me if I’m wrong

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