Home Forums Help/Technical Questions Is it safe to short the ring to ground by using a TS plug in the EXP jack?

  • This topic has 3 replies, 2 voices, and was last updated 4 years ago by zmix.
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  • #86351
    zmix
    Member

    I use a control voltage to adjust the delay setting of the Memory Man TT in my mixing studio.
    This CV is generated in my DAW and is output via the D/A converter.

    I have made some TRS to TS adapters to essentially “ignore” the ring connection at the DAW end (which would produce a negative DC voltage, and have a similar adapter plugged into the MM “EXP” jack – to ignore the DC voltage provided there for passive expression pedals.

    It would be nice to avoid using a second adapter at the MM end.

    Question: Is it safe to short the ring to ground by using a TS plug in the EXP jack?

    I suppose I can measure the voltage drop across a load to determine the output resistance of the signal at the ring connection, but I’d like to avoid an increase in current consumption or any potential damage to the pedal by presenting a dead short at that teminal.

    Any technical details about the DC source here would be helpful.

    #126273
    EHX STAFF
    Keymaster

    Please write the techs at

    info@ehx.com

    #126274
    zmix
    Member

    Thanks, done..!

    I’ll post any information here.

    #126277
    zmix
    Member

    I received a reply from John Pisani, the chief engineer for New Sensor / EHX.

    He said that using a TS plug in the EXP jack is no problem at all, and explained that the power to the ring connection is via a 2.2k resistor driving a 5V Zener to ground, and shorting across that Zener (by inserting a TS plug) will only amount to ~4ma through the resistor.

    Great..!

    For my own clarification, I crunched the numbers:

    9V supply, 2.2kΩ to ground = 4.0909 mA through the resistor

    9V supply, 4.0909 mA through the resistor = 36.818 mW dissipation

    The 2.2kΩ resistor will only dissipate 1/27th of a Watt, so there is no danger of that 2.2kΩ resistor overheating.

    Therefore: Using a TS plug in the EXP jack is safe.

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