Need Advice: Building a Vocoder Using Thor

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Raveshaper
Posts: 1089
Joined: 16 Jan 2015

09 Feb 2015

I did a quick search for how a vocoder works, but didn't turn up any decent technical details of the process that I could reverse engineer. So, in lieu of answers elsewhere I'll ask here.

How does a vocoder work? What is happening under the hood/inside the box?
My goal is to use stock devices to patch my own vocoder that can have different carrier signals per band for really rich and layered sounds.

What I tried to do was split my modulator signal into isolated bands, then send each band into a dedicated Thor. Each Thor allowed the carrier input to pass according to the modulator input using simple mappings in the Mod Bus like this:

Audio In1, 100, Audio Out1, 100, Audio In3
Audio In2, 100, Audio Out2, 100, Audio In4

The sound I got was kind of like a crunchy/square wave type FM synthesis instead of a vocoder. I played with all the settings for longer than I should have until I admitted that I was using the wrong approach and didn't know the right process.

Any takers?
:reason: :ignition: :re: :refillpacker: Enhanced by DataBridge v5

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LudvigC
Reason Studios
Posts: 93
Joined: 16 Jan 2015

09 Feb 2015

I guess you could make something like this:

1. Split modulator signal into frequency bands.

2. Send each band into a separate Envelope Follower (giving you a CV value based on the level of signal in that freq band).
I think this is what you missed; you need to use something like the MClass Compressor's Gain Reduction CV out.

3. Let the CV output of the Envelope Follower control the level of the appropriate carrier.

"appropriate" usually means the same frequency band (you split the carrier just like you did the modulator) but that's where you want to experiment, right?

If you *just* want to experiment with carriers, it's easiest to use the BV-512 vocoder for the analysis part (splitting the modulator signal and using the built-in envelope followers). Then route CV level outputs from the individual bands to level controls for whatever carriers you want.

I tried this once with sine waves from an NN-XT, the result of which can be heard at the end of this song: https://soundcloud.com/luiscarloz/super-pulver

/ LudvigC

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Raveshaper
Posts: 1089
Joined: 16 Jan 2015

09 Feb 2015

I missed that the first go around, did some testing since then and found the error of my ways.

The primary cause for my decision to try and not use BV512 at all is because of the headaches I've had with the discrepancy between its actual band count as opposed to its settings.
I don't want any of that "nothing happening on certain bands" nonsense messing up the patch (if possible).

That said, I wonder if I'm on the wrong track here. I'm coming around to the "less is more" way of thinking lately and I'm amazed sometimes at how much more you can get done with less.
Ill continue my experiment, even if I ultimately end up shelving it.
:reason: :ignition: :re: :refillpacker: Enhanced by DataBridge v5

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