What are you trying to listen with? Monitors (speakers) connected to Main L&R, headphones (which would be same signal path)? Something else?

The presets for vocoder are already setup properly assuming you turn on [A/D Input] (switch) and turn the gain up enough. This is the only way to start seeing the Vocoder Part's meter going up and down as you have.

For your custom Performance - there's a chance your output is not set to Main L&R. You can see this at the same screen as the effects routing screen in the lower-right. I'm guessing this all correct.

I just went through the same steps you did and got everything to work. Even without a microphone. I just had a 1/4 inch cable I touched the end of to make "noise" enough to provide the modulator with enough energy to make the 1o1 sample start sounding.

I started with Init Normal (AWM2) and went through the same steps you provided. I didn't have to set the A/D to L/Mono and could keep it in stereo although I switched this to L/Mono and everything still worked.

The only other thing I would say is to switch your A/D output to Main L&R (it should currently be "off" - which is fine) so you can hear your microphone real voice going out your main speakers. This is just a debug step so you can hear what the modulator is "hearing".

If I crank the gain all the way up I can barely hear my voice, distorted. I used the same cable and plugged the mic directly into my audio interface. It's plenty hot there.

I plugged my iPad into the A/D and it works just fine. So the mic is good, the cable is good, the A/D is good.

Warning: turn the Volume down. If you read the tutorial it warns you when you cannot get it to work it usually is not a Volume problem

And why this is so dangerous, is when you do find the parameter you’ve missed and it does come on… if you have the Volume “cranked” you WILL BE SORRY. So again, please, un-crank that volume, please. You do not want to lose a pair of speakers, or your hearing… the Vocoder can be unbelievably RUDE with high frequency content plus you are probably too close to your speakers — so you are in a known FEEDBACK zone. Please turn the Volume down before proceeding…

Let’s get a bit more specific about the gear… is the microphone a “Dynamic” microphone?
If not, you have a problem… let us know.

It should be a dynamic microphone (means it does not require any external power, dynamic mics work with permanent magnets).
And more specific about the cable… what configuration is the cable? XLR (female)-to-TS (1/4” male)?

Yes it is an EV dynamic mic.
Yes the cable is XLR female to 1/4" male. I purchased it just for this freaking vocoder. 🙂

I put a drum kit on Part 2 and used that part as the modulator for the vocoder and it works.

Okay, my cable is TRS. I don't see anything in the manual that specifies. I ordered a XLR to TS cable.
I found the info in another thread here called "Can't get mic to work."

Remember, turn the Volume down…

Let us know.

MODX owner's manual page 21 https://usa.yamaha.com/files/download/other_assets/5/1162395/modx6_modx7_modx8_en_om_a0.pdf

A/D INPUT [L/MONO]/[R] jacks
External audio signals can be input via these phone jacks
(1/4" mono phone plug). Various devices such as a
microphone, CD player or synthesizer can be connected to
these jacks and their audio input signal can be sounded as
the Audio Part.
In addition, you can use the special Vocoder feature by
connecting a microphone to this [L/MONO] jack and
inputting your voice to the microphone.

Source: https://www.mediacollege.com/audio/connection/connectors.html

1/4" Mono Phone Plug (TS, Tip-Sleeve)

Amazing what the right cable can do. Works great.

Let's Groove Tonight!

Same problem. Thanks for confirming my suspicion. Not all Mic cables are equal! (I could have sworn it worked before, but I can't find a single XLR to TS cable here!) $10 order and I'll have it fixed by tomorrow!