Moog Music Forum

I have a dummy/dead cable patched into the external audio jack and have the mix knob full right (to noise/ext). I assume the dummy cable breaks the normal and I should hear silence. With headphones on, I can hear noise triggered with the seq pattern. (With the VCA out to an oscilloscope, I can see voltage at ~ +/- .05v.)

Anyone else observe this?

Is this a case of analog electronics being imprecise, is it something that can be calibrated resulting from age or wear/tear, or is it something that shouldn't be there?

Inserting a cable into the socket does indeed break the normalised connection inside the socket. However, the signal connection on the tip lug is now just hanging there and will pick up stray signals. Unfortunately, the nearest stray signal is on the now disconnected normalised lug which is just a few millimetres away. This means the noise signal capacitively couples across the gap and you get to hear it faintly.

To avoid this, don't use a dummy lead but use a shorting plug. This is simply a 3.5mm jack plug which has the tip and sleeve connections inside shorted together. Inserting such a plug into a socket not only disconnects the normalised connection but also shorts the signal lug to ground and silences any stray signals.

ahhhh! makes perfect sense!!!! thanks for the assist!