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Active bass kill switch

Discussion in 'Pickups & Electronics [BG]' started by giuseppecaporus, Mar 27, 2016.

  1. giuseppecaporus


    Dec 19, 2013
    Hi bass player i'd like to put a kill switch with led(which goes on when sound is " killed")on my bass which as an active eq and i Guess i have to do it in this way :
    take a on/on 3dpt switch connect the two signal terminals to the left raw then a +9v for led on the under right connector and the output connection and battery +9 in the central raw is it correct . Thankyou . active_kill_switch_led.jpg
  2. This might seem like a good idea on paper, but in practice, there are a lot of issues that you need to consider. Firstly, you are trying to wire the switch to switch the battery. This is never done on a bass, because it leads to loud popping noises and momentary DC offsets that are not only annoying, but also bad for your speakers. If you want a killswitch, choose the more conventional method of shorting the output jack to silence the bass, and don't switch the battery at all. This method won't cause any noises or harm to your rig. The second consideration is the fact that the LED is going to be drawing a significant amount of current. (Much more than your preamp.) Depending on how often you use the killswitch, you will be draining the battery very fast. A better idea is to use a mini toggle switch, and put a red dot on the side that corresponds to the off position. This way, you can see whether or not the switch is turned off, but you won't have to waste battery power.

    As for the existing diagram, if you were to wire up that way, there would be many problems. Firstly, your wiring leaves the jack wide open, when you mute the bass. This is poor practice, because the bass will hum when muted. Proper killswitch wiring requires you to short the tip and sleeve terminals together, to reduce output impedance to zero. It appears that you are trying to switch the jack's ground, as well. Never do this. There should always be a connection to ground. Lastly, when you use an LED, you have to have a current limiting resistor in series with it. Skipping the resistor will cause the LED to explode and release a lot of nasty smoke.
    Last edited: Mar 27, 2016
    Rattman, walterw and mech like this.
  3. giuseppecaporus


    Dec 19, 2013
    Thank you for the replay i didn't understand it at all can please make a correct drawing draw thank you .
  4. This is the best way to do a killswitch.
    giuseppecaporus likes this.
  5. giuseppecaporus


    Dec 19, 2013
    Will it work with active bass if you think at this : the jack output is the tip ? emg-1.png
    Rattman likes this.
  6. It works for absolutely any bass, with zero exceptions.
    giuseppecaporus likes this.
  7. giuseppecaporus


    Dec 19, 2013
    Thankyou linean
  8. Hopkins

    Hopkins Supporting Member Commercial User

    Nov 17, 2010
    Houston Tx
    Owner/Builder @Hopkins Guitars
    Its pretty straight forward, but I see no real advantage over simply rolling your volume off
    wcriley likes this.
  9. MrLenny1


    Jan 17, 2009
    New England
    I second what Hopkins suggests.
    Or use an amp with mute switch or pull
    1/4 inch jack out a bit from the amp head to disengage ground.
  10. Will_White


    Jul 1, 2011
    Salem, OR
    Would putting the input and output on the center lug work equally as well? That's how I've been wiring mine but I'm always open to a better way. I initially did it that way with a momentary (on) off (on) switch [ground connected to the outside lugs] so I could stutter the signal faster. But now that I'm just using it as a standby switch I still connect the input and output to the center.
  11. bassbenj


    Aug 11, 2009
    Of course the second half of the circuit is the LED! Since the switch shown in the diagrams has another half you can use that to turn the led on and off. An LED can draw considerable current which can drain a 9 volt battery (presumably the bass won't be muted for long periods of time). Hence to optimize it takes a little care. First you want to pick a nice high output low current LED. You want one that is really bright with only a milliamp or so. Radio Shack usually has some like this in their drawers. And then you want to cut it back even more until it's just decently visible. You do this with a high value resistor in series With 9 volts try something in the range of 10k to 100k to find the biggest value that you can still see the LED. And finally the LED is wired from the 9 volt battery red wire (+) to the resistor to the LED and the LED is then run not to the battery negative but to the output jack ground! This then turns the LED off when you remove the cable from the bass to turn off the preamp etc. OK?

    I really like the idea of a "mute" LED! My active basses don't have batteries and are run from TRS power from the amp so I can have as many LEDs etc as I want. Many of my basses already have "power" LEDS to show that power is active from amp. In my case it would be a simple thing to add a mute LED or even change to a multi-color power LED that changes color when you mute! I would note that my LEDs also shut off when you run from a battery and not from phantom power to cut current draw.
    giuseppecaporus likes this.
  12. If you use a flashing LED, it will use a fraction of the current of one that is steadily lit. I used to build pedals like this to save battery power.
  13. giuseppecaporus


    Dec 19, 2013
    I think I'll try it !
  14. Sometimes, circuits don't like to drive a zero Ohm load, and so this scheme lets you err on the side of caution. In general, however, it works just as well to connect the input and output together, on the same terminal. With EMGs, or any passive bass, it's fine.

    A side note: When wiring a killswitch, it is important that the switch shunt the output jack. A common misconception is that you can simply disconnect the circuit from the jack, but if you do that, you can get a lot of hum. (Just like when you have an instrument cable just lying out in the open.) As long as the jack gets shunted, the wiring is usually fine.
    Will_White likes this.
  15. lamarjones

    lamarjones Supporting Member

    Aug 27, 2002
    Raleigh, NC
    Glad I found this thread. I have a bass with a kill switch and I prefer it much more than value rolling. Singer is talking, I'm spacing out, and then all of a sudden it's. Time to. Go.. Pluck that first note, things are dead and. If know where the switch is then I can get going a fair bit quicker.

    Just saying, there are advantages. Suggesting the mute switch on the amp is way out for some situations.
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