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Replacing Wah Tranistors

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  • blueman335
    replied
    Re: Replacing Wah Tranistors

    Originally posted by Zombiwoof View Post
    Look for BC109B transistors, they are medium gain like the vintage wahs used, 109C will be in a higher gain range, like the stock transistors. The Fuzz Central site recommends them to be in the 300-400 hfe range as I recall for their Clyde McCoy mods.
    Al


    The BC109C's I got are supposed to average 550 hfe. I just put them on a multimeter and they're all in the low 700's, which is too hot for what i want. From now on, I'll go with BC109B's.

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  • ErikH
    replied
    Re: Replacing Wah Tranistors

    They could. They could also be biased hot too. The Boss DS-1 suffers the same ill by having the input transistor biased too hot. It takes tweaking the resistors that are tied in to the transistor to lower the gain and then rebias it. See this link for how this can be done on the DS-1, which I've done a few times myself. http://www.muzique.com/news/fat-mod-for-the-boss-ds-1/

    I'd have to look at a schematic of those wah's to attempt to figure which resistors and the values. It all depends on the transistor and it's operating range. Even if you swap the transistor, it may need to be rebiased for proper operation.

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  • blueman335
    replied
    Re: Replacing Wah Tranistors

    Don't the hot transistors in recent production V847's and GCB-95's cause some harshness to the tone, especially in the toe-down position?

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  • ErikH
    replied
    Re: Replacing Wah Tranistors

    It's also a good idea to check the manufacturer spec sheets for the transistors to make sure the pin-out orientation is the same for all of them. I have come across some where the base and emitter are swapped and I had to cross them to ensure it was installed correctly.

    IME with wah's, you'll get more of a change in sound with different inductors vs. the transistors.

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  • blueman335
    replied
    Re: Replacing Wah Tranistors

    Got it. Thanks!

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  • PFDarkside
    replied
    Re: Replacing Wah Tranistors

    Are the current and new ones in a package different than the image above? Just match B, C and E on the old and new.

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  • blueman335
    replied
    Re: Replacing Wah Tranistors

    I've got teh transistors. Just need to know which way to install them.

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  • Zombiwoof
    replied
    Re: Replacing Wah Tranistors

    Look for BC109B transistors, they are medium gain like the vintage wahs used, 109C will be in a higher gain range, like the stock transistors. The Fuzz Central site recommends them to be in the 300-400 hfe range as I recall for their Clyde McCoy mods.
    Al

    Leave a comment:


  • blueman335
    replied
    Re: Replacing Wah Tranistors

    I'm looking at swapping resistors on a GCB-95 and an V847.

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  • PFDarkside
    replied
    Re: Replacing Wah Tranistors

    Yes, the Base, Emitter and Collector must all be oriented correctly. Do you have a specific mod or schematic you are following? Iím assuming it already has NPN transistors. Simply replacing the transistors may not have the effect you are looking for, depending on the stock biasing.

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  • blueman335
    started a topic Replacing Wah Tranistors

    Replacing Wah Tranistors

    Looking to replace the hot stock wah transistors with more vintage sounding ones (BC109C). Does it matter which way the outside prongs are soldered in? Or do they work the same in either direction?
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