Tutorials and How-Tos

Effects Tips/Tutorials

How to create true pitch vibrato

So you'd like to get those sweet vintage Boss VB-2 Vibrato tones out of your squeaky clean new Axe-Fx...here's how.

True pitch vibrato is created by modulating the time on a 100% wet delay line. Think about it. Have you ever twisted the delay time knob on an analog delay to get those cool alien spaceship sounds? Same concept only the knob twisting is done via an LFO and there is no dry sound to water down the effect.

Perusing the Axe-Fx's available effect blocks, the chorus is the best fit for this task. Compared to the delay block, the chorus block allows smaller increments of time delay and doesn't have a feedback (regeneration) path which we don't need anyway.

Checking the Chorus block's basic parameters, we have VOICES which is how many voices our vibrato will have. If you want to nail the VB-2 you'll only need one voice. The minimum choice is 2, but we don't really have to vary but one of the voices. RATE is the rate of the LFO and is directly analogous to the rate control on the VB-2. DEPTH is how much the delay time varies.

According to Cliff, the LFO varies the delay time "bipolar" meaning that it adds and subtracts delay time from the nominal delay time which is set in the advanced parameter menu. MIX should be set 100% wet to vary the pitch of the original signal with no original signal present. TEMPO you can use if you want to lock the rate to a songs tempo.

This isn't an easy process, so if you're uncomfortable with routing things around in the Axe-Fx, go back now. Make your noise with a nice ring modulator or formant filter instead.

• Setup your guitar sound as you'd like. You might want to leave a few spots around where you're going to put the vocoder in your chain so that you can add other effects in later. The space right in front of the vocoder should be a mixer block. This is important. Your chain might look something like this:

1)
2)	Drive -	Amp -	Cab -	(shunt) -	Mixer -	Vocoder -	(shunt) -	Reverb ->
3)
4)

• For the "robot effect" on your guitar, you don't need anything else. The vocoder will have a fixed spectrum and defaults to not using a second input. It'll sound a bit like you're playing guitar through an air conditioner.

• If you want to use a vocal input, you need to connect your mic up to the Axe-Fx. I ran mine into a preamp and then into Input 2 (the effects loop return). The preamp part is important since the Axe-Fx will be looking for a line level signal.

• Now add the effects loop block into the row beneath the guitar's path. You might want to leave a couple spaces for hooking up a compressor (for de-essing) and/or noise gate on the vocal line. The end of the vocal chain should feed into the mixer block you setup before. Your chain might now look like this:

1)
2)	Drive -	Amp -	Cab -	(shunt) -	Mixer -	Vocoder -	(shunt) -	Reverb ->
3)		Eff. Loop -	Gate -	Comp /
4)

• Now set the Mixer up to pan your guitar signal (on Row 2, in my example) 100% left and the mic signal (on Row 3, as I've drawn it) 100% to the right. You could bypass the vocoder block to make sure they're in the correct places in the stereo spectrum.

• With the inputs setup, engage the vocoder block. Check that INSEL is set to LEFT. This means the synthesis/carrier/guitar signal is coming into the left input. If hitting a chord and talking/shouting into the mic doesn't make any sound, try changing INSEL around. It's important to note that you will only hear something when you have both the guitar and your face making noise. The mic input is now a spectral gate on your guitar signal. If you make nasal sounds, those nasal upper-mids get through. If you have a low, boomy voice, mainly the lows get through. If you're silent, nothing gets through.

• You can tweak a lot of parameters in the vocoder, which I won't get into yet, but here are a couple key points to keep in mind:
  • You can clip the output if your guitar signal is too loud, but I found I was more likely to do it if my mic signal ran too hot. Keeping a compressor in line to limit the mic's strength can save some nasty noises.
  • Vocoding sounds best with a harmonically rich synthesis input. Lots of fuzz on your guitar signal makes good fodder. Buzzy sawtooth synth waves work well too. A thin, clean guitar sound might cut through a mix nicely, but it will have trouble showing the intricacies of your voice.

Routing Tips/Tutorials

How to set up two different effects lines

If you want to set up two different effects lines for 2 guitars with out using the fx loop:

You can do this with the mixer blocks.

Put mixer1 in row2 column1 and mixer2 in row3 column1.

Set mixer1 pan1 to full left, mixer2 pan1 to full right. Set both mixer output modes to mono. In the routing grid the main input is always in row1 even though it shows up down the left side of the display.

Now row2 is your left input and row3 the right.

Be sure to set you Audio I/O to stereo for the main input. Also, if you are using the rear inputs make sure to set your mode to analog rear. You can use the front panel input along with the rear right input. In this case set the mode to analog front. The mode only controls the selection between front panel and rear left.