What is the purpose of the normalization probe?

[Ward]

So as many people do I was reading some of your schematics as reference and I saw that some modules have “normalization probe” connected to the TN/normalized pin of input jacks. I searched the forum and saw that by sending a noise pattern and checking if the ADC reads match this pattern you can check if a cable is connected or not.

Now I have some questions about the purpose of this technique:

• Why would one need to know if a jack is connected or not?
• If a jack is removed and thus the normalization probe pattern is send to the ADC and it take 32 reads before verifying that the reads are actually the normalization probe, how do you prevent the 32 reads from ending up in the synthesis parameters and affecting the sound (for a very short amount of time).
• If I connect the TN/normalized pin to GND it would also work right? (no jack connection: tip=GND, sleeve=GND and thus ADC voltage=0)

[pichenettes]

@Ward

• Why would one need to know if a jack is connected or not?

Check the documentation of the module.

For example, in the case of Rings, an internal excitation signal is synthesized on each new note on the V/O input if the main IN input is left unpatched.

Or in the case of Plaits, if a CV input is left unpatched, its attenuverter controls the amount of internal envelope.

@Ward

how do you prevent the 32 reads from ending up in the synthesis parameters and affecting the sound (for a very short amount of time).

You can’t, and you’ll have to deal with 0.1% of your customers complaining about that.

@Ward

• If I connect the TN/normalized pin to GND it would also work right? (no jack connection: tip=GND, sleeve=GND and thus ADC voltage=0)

If you do that, the module won’t be able to make the difference between these two situations: a/ a jack is connected, with a voltage of 0V b/ no jack is connected.

If you modify Plaits or Rings that way, internal envelopes/exciters won’t work.