[RWP] Vocoder

[Patrick Perdue]

Generally speaking, no, unless you're using a vocoder that happens to 
have it's own synth engine, like Klanglabs Vokko. Most don't.

A traditional vocoder takes two audio inputs, usually the modulator (the 
signal to be vocoded) on input 1, and the carrier (the thing over which 
the modulator is, well, modulated,) on input 2.
There are a bunch of different ways to achieve what I'm about to 
describe, but this is how I'd setup routing for a vocoder input, in 
order to keep things discrete for additional processing for both input 
and output if necessary, such as compression and filtering.

First, set up two tracks for your two individual sources, or one track 
with mod panned hard left, and carrier panned hard right. In the case of 
a single stereo track, you could either insert the vocoder directly on 
the track, or send this track to another dedicated one with the vocoder 
effect on it. If you send a single stereo track to another one dedicated 
to a vocoder, make sure that track's master send is off. Otherwise, if 
the vocoder has been inserted as an effect directly on that track, leave 
it on, unless you're doing custom hardware output routing or something.

Sending dedicated source tracks to the vocoder's input, however, has 
additional benefits. Let's say you want to compress your vocal track 
before it hits the vocoder, which really does help sometimes, as well as 
applying a highpass filter, but you don't want to effect the carrier 
source at all. You can simply stick those effects on your modulator 
track, and you're good. With a single stereo track, that's harder, 
though not impossible, to accomplish. The "not worth it" factor is 
pretty high, and it's just easier to work with individual tracks.

If you have a dedicated track for each of your sources, let's say track 
1 is a microphone, and track 2 is a softsynth putting out a sawtooth 
wave form, send both of these tracks to another track with the vocoder 
inserted as an effect, and unroute both from master, unless you want 
both wet and dry signals from each track to show up.

Now, use the ReaAccess track I/O, shift+i, on the vocoder track, then 
select receives. You should see the tracks you are sending to the 
vocoder. For your microphone track, route input channel 1 to output 
channel 1, and for the synth track, route channels 1/2, or just 1 or 2, 
to only channel 2 of the vocoder track. It is very important to not have 
either of your tracks routed to both channels 1 and 2 of the vocoder 
track. If this happens, you will essentially be vocoding something over 
itself, which is probably not what you want to do, although, depending 
on the vocoder algorithm you use, it can either be interesting as a 
stupid effect, or incredibly boring and pointless.

In this dialogue, mono channel routing comes after all the stereo pairs 
from 1/2 to 63/64, and in this case, you want to generally send one 
channel directly to another on a different track. Most vocoders don't 
have stereo modulator or carrier inputs.

Now, make sure your modulator track is armed, and that monitor is set to 
normal. This insures that the track's output is actually sending to 
other tracks as you send live input to it. Otherwise, those other tracks 
will only get audio when playing stuff that has already been recorded on 
that track.
You'll want to arm the carrier as well, unless you want to record both 
parts at separate stages. This is theoretically no different if you're 
using a piece of hardware to generate your wave form to drive the 
vocoder, or a piece of hardware connected to a physical input on your 
sound interface.

If you've never used a vocoder before, you may want to experiment with 
the types of wave forms you use for a carrier input. I'd suggest 
starting out with a raw saw wave, or playing with string and pad patches 
with very little, if any, attack and release. The very boring ReaSynth 
can supply you with the basic wave forms, but you won't get anything fun 
like monophonic or portamento.

Of course, the possibilities are endless. You can use any given number 
of things to get interesting results, but those are good starting points.

Also, the vocoder which comes with Reaper isn't really that great. 
Depending on the type of vocoder sound you're looking for, I'd suggest 
trying a few other ones. The free MDA vocoder is relatively OK at 
providing a classic vocoder sound, and is generally more intelligible 
than Reaper's default one, although you'll want to tweak the defaults on 
just about anything you use to make it suck less.

I have several hardware vocoder solutions, ranging from the really not 
so awesome algorithm on my currently broken Ensoniq D/P4, the not much 
better one from my Alesis Ion, the slightly nicer one from my Digitech 
Studio Quad IV and Yamaha Motif XS, to my over all favorite, the 
Electrix Warp Factory. I like this unit because it offers the most 
clarity with 24 bands, and has a huge amount of frequency response. It's 
also the only unit I've seen with a stereo carrier input. It, however, 
doesn't have the "classic" sound I want sometimes, though it is 
generally a really cool unit to play with, so I usually fall back to the 
built-in vocoder on my Motif XS to get that sound.

On 5/20/2012 4:56 PM, Alexander Westphal wrote:
> Hello!
>
> When I want to use a vocoder for an audio track, is it as simple as I'm
> about to think? I would first record an audio item, insert a vocoder as
> effect and then set up the track for midi recording and play the parts I
> want to have. Could this be so easy?