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Using digital keyboard pedal as....

Discussion in 'Sound, Music, and Intercom' started by Anonymous067, Apr 19, 2009.

  1. Anonymous067

    Anonymous067 BANNED USER

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    How would one go about using a digital keyboard sustain pedal as a mute switch hooked up to an insert jack of a soundboard?
     
  2. Chris15

    Chris15 CBMod CB Mods Premium Member

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    Ok so there's the quick and dirty way that by all logic should work or there would be the more proper option...

    Quick and dirty - make an insert lead that has a TRS plug to go into the console with T&R shorted and then that point connected by whatever necessary interface to the footswitch and the return of that switch goes to ground (Sleeve of the TRS).

    The better version will involve a buffer stage with an op amp and will need to know the wiring of the particular insert that it will be plugged in to. It will also need an external power supply to produce the plus minus 15 volt rails for the op amps.
     
  3. Les

    Les Well-Known Member

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    Make sure you know the "polarity" of the pedal you are using. Some pedals are normally open and some are normally closed circuitry. I suppose this would make a difference in it's operation and how you would go about setting it up.
     
  4. Andy_Leviss

    Andy_Leviss Active Member Premium Member

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    Well, there are two types of insert jacks. There is the single-point, unbalanced insert, which is usually standardized as tip=send, ring=return, shield=common, and then there are dual-point inserts, with separate balance send and return.

    I imagine you're using a console with single-point, in which case I'll sum up what the previous posters have mentioned. You want a normally-closed (NC) footswitch, and you want to rewire it with a TRS connector (it normally has a TS connector) so that the switch is going between the tip and ring. When you press it, this connection opens, breaking the signal.

    If you get a switchable footswitch (which has a slider on the bottom to choose between NO (normally open) and NC operation, you can also switch it to be NO, in which case it becomes a push-to-talk.

    On a dual-point insert, your best bet would be to wire a box with a TS jack for the footswitch, and a balanced out and in to connect to the console's insert jacks. The insert in/out are connected straight through, and the jack for the footswitch gets wired in parallel, with the tip wired to pin 2 of one of the XLRs, and the sleeve to pin 3. In this case, you want a NO switch; pressing the switch will short pins 2 and 3 together, effectively muting them (this is how mute switches in most switchable dynamic mics work).

    HTH,
    Andy
     
  5. Anonymous067

    Anonymous067 BANNED USER

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    If I wire the pedal with the NC configuration, and connect it to a TRS insert (yes I have the unbal TRS), is the pedal then an on-off switch?

    Thanks!
     
  6. Chris15

    Chris15 CBMod CB Mods Premium Member

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    Basically an insert jack contains the output of the preamp and the input to the rest of the channel strip, usually the two are shorted without any jacks in.

    If you substitute an NC switch for that short what comes out goes back in (there is a small possibility of inducing hum... Use a 2 core shielded cable and ground the shield at the console end).

    My only worry would be whether you would get hum problems with a floating input created by disconnecting the preamp, but given that things are running at line level by that stage it's not so bad....
     
  7. Anonymous067

    Anonymous067 BANNED USER

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    Makes sense.

    So does the NC pedal act as a punch-in/punch-out style or as a momentary PTT style?

    I guess what I wanna be able to do is push the pedal to "unmute" a channel, and push the pedal a second time to "mute" the channel.
     
  8. Chris15

    Chris15 CBMod CB Mods Premium Member

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    That my friend is entirely dependant on your footswitch. Most are momentary ergo for an NC push to mute. You should be able to find a latching one I would think. Else you'll need some circuitry to convert momentary to latching which will probably be messy...
     
  9. Anonymous067

    Anonymous067 BANNED USER

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    the latching part is the part I was trying to find the word for! Thanks!

    Now i'm just gonna go google some stuff...I'm not even going to try re-wiring the old pedal I have now. Sounds like it's easier to just buy a new one!

    So I need a NC latching footpedal correct?
     
  10. Chris15

    Chris15 CBMod CB Mods Premium Member

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    NC is literally Normally Closed and NO Normally Open. Once you start talking about a latching switch, the two become the same because there is no sprung return to either open or closed. Essentially you want a latching single pole switch. Beyond that, the only differences are likely to be in connectors, mechanical robustness, etc.
     
  11. Anonymous067

    Anonymous067 BANNED USER

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  12. Anonymous067

    Anonymous067 BANNED USER

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    How would I go about re-wiring the connector?
     
  13. TimmyP1955

    TimmyP1955 Active Member

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    TRS plug and:

    Single pole-single throw switch: Connect tip to one terminal and the ring to the other terminal. That's it.

    Single pole-double throw switch: Connect the tip to the center terminal and the ring to either end terminal (or vice-versa).

    Double pole switch: Just ignore one pole and follow the instructions above.


    I don't think noise will be a problem so long as you use a shielded cable, with the shield connected to the sleeve (and connected to nothing on the switch end).
     
  14. Chris15

    Chris15 CBMod CB Mods Premium Member

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    That dual switch foot pedal is wired with a single TRS jack from what I understand. So I expect that the sleeve is a common and then tip and ring are the two switches. As it stands you would need external circuitry or to modify the switch to add another socket.

    Beyond that, you want the switch itself between tip and ring of the insert point.

    The single TRS could work with a short to ground but I myself am still unconvinced that the theory there will work in practice...
     

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