Home Forums General DIY Pedal Discussion Input- and output impedance on DSOTM Fuzz

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    Have anyone measured the Zin and Zout on the DSOTM Fuzz pedal? Barry didn´t know and asked me to post the topic here. Unfortunately, I haven´t got the equipment to make the measurements myself.

    Kind regards Karsten 🙂


    My actual PM answer was a bit more involved in an effort to be helpful (see below):

    Regarding the DSOTM:

    “It is variable but follows the rules of most conventional guitar pedals in that you want pedals to have low output impedance and high input impedance. Many pedals have a 500k to 1M input impedance (see schematic). This gives max signal transfer and will help preserve the full range of the sound.

    It has a higher input impedance than a classic Fuzz Face circuit (meaning it works well with wah pedals and does not need to see the guitar directly at its input), it cleans up much more gradually and controllable with the guitar volume, it has the ability to get much more fuzzy than a typical Fuzz Face (it can function as a silicon Tone Bender), has a multitude of different tonal variations (and is generally smoother sounding in all its settings than a classic Fuzz Face circuit), it has a much more usable low-gain range.

    I do not have exact numbers or currently the time to test but you should find that when mapping this circuit is quite versatile as to where you wish to place it in the chain.

    If you require more detail please make a forum post.”


    Also to be clear to anyone reading this, PM’s are for order issues. All build questions need to be posted in the forum as I am not always available to answer PMs personally because I am working.

    Below is a Photo of the Contact Me form when submitting questions:



    Barry is correct.  The input impedance varies depending on several factors such as the beta of the particular transistor and the setting of the gain pot.  Likewise the output impedance also varies depending on pot settings.

    The important factor is that the input impedance must be higher than the output impedance of the device that preceds it in order to prevent loading of the signal.  The output impedance is also variable but is low enough to match up with succeeding devices.

    You can find test circuits online that will permit you to accurately measure and calculate your specific impedances for the conditions you desire.

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