Request: MXR Noise Gate

Here’s my take on a modded version of the MXR Noise Gate based on the tonepad schematics, yet to be verified. I decided to incorporate most of the suggested mods forgoing only the “momentary” switch. Excited to find out whether this one works or not. Let me know if you build it.

Update (08.10.2011): Built this one today and it seems to work. It removes noise, but the additional controls didn’t initially seem to do much. This was probably because of my very rudimentary test setup though. I’m calling this one verified.

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27 thoughts on “Request: MXR Noise Gate

  1. I’ve built it too.
    To reduce noise I have replaced C10 with 100uF + 100nF and I have added 470ohm in series with Attack pot.
    I have jumpered Attenuation as I don’t need it.

  2. Without having a circuit to confirm, I’d think you should see approx. +5V. Are your readings way off?

  3. What is the approximate correct value of the bias voltage Vb?
    I do not get 5,1V with a 5,1V Zener diode.

  4. Do you mean the gate threshold doesn’t work at all? It’s supposed to sound the same as long as you feed it a signal large enough to break the threshold.

  5. Hi harald. I have a problem about this pedal. I have checked it several Times but the input sound is exactly the same that the output one (when the pedal is ON)

  6. ed,
    I don’t know the circuit well enough to give you a good answer. It’s certainly possible, but it may well require a bit of designing in.

  7. I’m sure there are pages out there on the Internet that could explain the basics of a noise gate. I haven’t played around much with this circuit, so take what I say with a grain of salt. The sensitivity pot is used to set the minimum threshold; you need to feed the circuit a sufficiently large signal in order to “open the gate” and allow the signal to pass through. The attack and release pots control how fast the gate reacts and opens/closes respectively. The attenuation pot I’m not sure of.

  8. Please can anyone explain me how any pot of this pedal has to work? I don’t know if it works right. Thanks to everyone

  9. If I only want the sensitivity control, can I just jumper the other connections or how should it be done?

  10. What to share some more experience about this stomp. Trying to remove pop at start of a singnal and noticed that inreasing C10 cap value helps a lot. The bigger cap is, the less unnecessary noise you have when gate opens or closes. 470uf fits best for me. Also, since capacitance cap depends on size, I’ll give you an advise – use 10v cap. Capacitor of this voltage will be smaller than 16v or higher. Don’t worry about breakdown of your cap, It is connected in parallel to 5.1v zener and will work happily ever after.

  11. I was surprised, but it doesn’t work properly with 1M, so changed to 1.8k
    BTW build report:
    Matched 2n3904 hfe350 and 2n5952. Firstly it doesn’t work at all. Then I put 1.5k instead of 1M between Q3 and Ra, it helped. Then was a strange pop in start of decay. Also after about a sec after opening gate there was strage noise with the main signal, like fuzz.
    Then I canged 2n3904 with hfe350 to hfe250 (measured about 30 and can’t find lower) and Noise gone. But quite pop at the start still there add 500ohm before the attack pot and it get quiter. I think if I put 2n3904 with hfe150 pop will disappear.
    Tried to change Attack pot to 50k, but it has effect only if increasing to 25k, if you increase resistance, singal just geting quiter.

  12. I had to look up why I put a 1K8 resistor there. If you read the build reports on that tonepad layout you’ll find that this 1K8 resistor is a fix that several people have had success with, and it fixed my build as well. I guess I should have added some info on this on the layout. Did you get it to work with the 1M resistor?

  13. I built it today, works great.

    The mods are ok, attack control is a little weak but works, the attenuation control seems to just blend the non-gated signal back in (not sure how I would use that). But even with non-matched transistors (I kept switching one out until it sounded best). It sounds and works way better than my old Boss NF-1.

  14. i couldn’t find 2n5952 and 2n5485 , any suggestion? i bought 2sk30 but i’m not sure it will work.

  15. thanks for the advice!

    turns out the cut in the ground lane was still conducting *facepalm*.

    don’t know how many times i’ve checked the whole board and managed to overlook this…

  16. I read the build reports over at and noticed a lot of people have trouble with this circuit. Afraid I’m not able to help you much, but I recommend you have a look at those reports at least. Might give you some pointers.

  17. ok, i’ve got it go produce sound by installing the attenuation pot. with it set at 0 Ohm, there’s almost no output signal which was my problem previously.

    still, the sensitivity knob isn’t doing anything.

    with the attenuation at full, there’s no noise reduction but only a slight volume drop.

    i’m about to give up on this. i’ve build several pedals and a few amps successfully over the past months, but this guy here seems to refuse to work on my hands 🙁

  18. hi,

    i just tried building this pedal without the mods but i can’t get it to work. i’ve checked all parts and the wiring several times now and tried different ICs and transistors, but i only get a very low gain and quiet signal from the output. since your layout is verified, i’m obviously doing something wrong here.

    here’s what i did to bypass the mods according to tonepad’s schematics: and

    since the ‘mods’ are additional pots in the circuit, i thought i could just bypass them since i figured i won’t need these additional controls.

    1. bypassed the attack control by connecting i1 to j1
    2. bypassed the attenuation control by connecting d22 to j22
    3. bypassed the release control by connecting g1 to d22 (Vb)

    any help/advice would be greatly appreciated 🙂


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