Gear used in this article:

Axe-Fx II (Original, Mark II, XL, XL+)

Update 12-22-11 – If you use a Pitch block in one of the rows, be sure to set the Pitch Source to Local Mono. If you don’t, signal from the other input will feed into the wrong row and sound funky! Thanks to Bakerman on the forum for this tip.

UPDATE 12-19-11 – You can use Volume blocks instead of Mixer blocks (thanks to Stringer76 on the forum). I’ll show this at the bottom of the article. I’ll also show using 2 Amp blocks.


For years I’ve been playing Ernie Ball John Petrucci guitars both because I’m a huge Dream Theater fan and because it’s such a great guitar! Playing music in Hawaii, there is always a demand for an Acoustic Guitar sound. I knew I wanted to play an Electric Guitar and have certain chorus cleans and distortion tones, but I didn’t want to switch back and forth between an electric and acoustic. Ernie Ball guitars have a Piezo option which includes a 2nd pickup system that has a separate output and creates an acoustic guitar sound.

You can either blend the 2 sounds from the guitar into the same cable/signal, but acoustic guitar usually doesn’t sound good through an electric guitar setup. So you have the option of running 2 cables (or a specialized Y cable) to separate the electric and acoustic sounds to different amps. This is where it gets really cool as you can blend the two distinct sounds together, similar to how a keyboardist might blend piano and strings, for example.

Usually people send the electric signal to their electric rig (effects, amp, cab) and the acoustic signal to an acoustic amp or to the PA system. You have separate volumes for each sound and can blend the 2 sounds to your liking. I usually use a dry acoustic tone and a chorus clean electric blended for a very full-sounding clean tone.

My rig used to be a Mesa Boogie Roadster with 2×12 Lonestar cab and the TC Electronic G-system for the electric sound, and a Presonus Eureka preamp into a JBL EON 15 powered speaker. I definitely carried the most gear compared to other guitarists here! It sounded great and I’d probably still be using that rig today, until the Axe-Fx came along. The Axe-Fx quickly replaced my electric rig, but I still used the Eureka preamp for my acoustic sound. I knew there was a way and finally figured out how to run both signals into my Axe-Fx Ultra, since there are multiple inputs and outputs. Suddenly the gear I needed was cut down and I only needed the Axe-Fx and a powered speaker! I posted a video of my previous patch setup using the Axe-Fx Ultra.

I have since refined the setup since getting an Axe-Fx II and I believe you can still do everything I do here on the Axe-Fx and Axe-Fx Ultra. My setup talks about using a single guitar with 2 outputs, but this method can be applied to 2 separate guitars as well with a few additions. Anything in the example/tutorial below that mentions my acoustic or piezo signal can instead be a 2nd guitar.

I/O Settings

First let’s talk about I/O settings. I prefer to use Input 1 for both guitars/signals instead of using Input 1 for electric and Input 2 for acoustic. One of my favorite features of the Axe-Fx is Copy Out1 to Out2, found on the Audio tab of the I/O menu.  This gives me a volume knob for the signal sent to the PA system using Output 1 and a volume knob for the identical signal sent to my powered speaker using Output 2.  If you use Input 2 for the 2nd guitar, you lose this functionality and you have to put an FX Loop block in each preset. Which means you lose the ability to set Output 1 for the PA and still adjust your own stage volume (Out 2) without changing the gain staging for FOH.

The Axe-Fx II offers separate Input Level settings for 3 inputs: Front Instrument Input (which is actually Input 1 Left), Rear Inputs Left & Right (which share the “Input 1” setting), and Input 2 Left & Right (also shared).

I also use the Instrument Input on the Front Panel for the electric and Input 1 Right on the Rear Panel for the acoustic.  The main reason for this isn’t the “secret sauce” on the front input; it’s so I can use the 2 separate input volumes that the Axe-Fx II offers.  (Sorry Ultra and Standard owners, the front and rear inputs share the same physical volume knob.) My Piezo signal is usually hotter than the electric singal, so I like that I can tailor each input as needed.  Depending on your setup, you might be able to just use the rear inputs and the Input 1 volume and not worry about getting a cable to the front of the Axe-Fx.

Then you just set Input 1 Mode to Stereo on the Audio tab of the I/O menu.  It’s very important that you know that now your Electric signal is Input 1 Left and your Piezo signal is Input 1 Right.  You can have your output mode as Mono or Stereo and you’ll still get both signals after we finish our preset setup.  I ran a mono output for years, and just recently started running stereo.

Preset Design

Shunts

Now on to the preset. Start with a blank preset and add Shunts all the way across Row 1 and Row 2.  We are going to have separate signal paths so each guitar has its own effects and tone shaping.  Since most of the presets on the Axe-Fx start with Row 2, I have chosen to leave Row 2, 3 and 4 for my electric guitar sound.  Row 1 will be for my acoustic sound. This might get confusing later, so heads up.

Input Gate

Next, go to the Input/Gate tab in Layout and turn this gate off by turning the Threshold to Off.  This is due to something I didn’t realize in previous tutorials. Since I am using Input 1 for both guitars, the Input Gate is shared for both signals.  On a clean patch this may not be a problem.  But on a high gain patch, I would play my acoustic signal only, and I would hear noise from the electric row. I adjusted the Input Gate to get rid of that noise, but then it was clamping down too hard on the acoustic sound.

I realized each source needs its own Noise Gate block, so it’s best to turn off the Input Gate that’s shared with both inputs.

For this specific method of sharing Input 1 for both guitars, it’s best to turn off the Input Noise Gate. Just set the Threshold fully counter-clockwise to “Off” as shown in this picture.

Mixer Blocks

NOTE – This next section talks about using 2 Mixer blocks.  Since this posting, I actually now recommend using 2 Volume blocks instead.  They essentially do the same thing, but there are 4 Volume blocks available (leaving 2 others for actual volume purposes) and it is much easier to set.  So please read the next section, but be ready to substitute Volume blocks for the Mixer blocks.  See this note at the end of this post for details on setting the Volume blocks correctly.

Starting with the electric row, I add 2 things to every patch: Mixer 1 and Gate/Exp 1.  The Mixer is responsible for splitting our Stereo Input 1 into the correct rows. Because the Mixer is in Column 1, please note that it acts a little differently than it normally would in any other column.

Note that I’ve chosen to associate Mixer 1 with “electric guitar” regardless of what row the electric blocks appear in, and likewise associate Mixer 2 with “piezo/acoustic/guitar 2” the same way. This consistency helps when dealing with multiple presets. Mixer 1 is always “electric”, Mixer 2 is always “acoustic.” Feel free to associate things how you prefer.

On Page 1, leave GAIN1 all the way up, but change BAL1 fully counter-clockwise.  (Gain and Balance 2-4 have no effect since the Mixer is in Column 1; that’s why the Mixer has to go first). This tells the row that you only want Input 1 Left to be sent to the rest of the row. Remember, our electric guitar is in the Front Input, which is Input 1 Left.

On Page2, leave the Level at 0.0dB, but change the Output Mode to Mono.  We want only the left side of Input 1 to come into the electric row, but we want it sent out of both sides, not panned, so Mono is the correct setting.  If you don’t change this, you’ll only get sound from the left output.

As mentioned earlier, we disabled the Input Gate, so a Gate block is now necessary to control any noise typical with an electric guitar and high gain amps – set this as needed.  From here, you can add an Amp and Cab block, and anything else you would normally use in a patch. So by now you may have something that looks like this:

If you play the preset now, it won’t sound right. Even with only the electric guitar signal setup, you’ll hear a dry guitar sound along with your effected row.  We’re not done!

On Row 1, add Mixer 2. Again only GAIN1 and BAL1 are functional since it is in the first column. Leave GAIN1 all the way up, but turn BAL1 fully clockwise.  This tells the row that you only want Input 1 Right to be sent to the rest of the row. On Page 2, leave Level where it is, and change Output Mode to Mono just as before.  Now you can add anything you want to the rest of the row for your 2nd guitar.

If you are using a setup like mine, you may want to add a Graphic EQ and Multi-Band Compressor after Mixer 2.  The EQ lets you shape your tone and the MBC helps control the full tone of an acoustic guitar. But you can add any blocks you want for this 2nd guitar.

Here is the full layout of my Clean Chorus/Acoustic Patch:

Summing the rows as an option

I sum the 2 rows near the end so they share a Filter block, which I use for a boost.  The 2 signals remain separate throughout the entire chain until this point, so the Delays you see in the electric row don’t affect the acoustic at all, and so on. But because both sum to the Filter block both are boosted at the same time, which is how I want it to work. I could also use a single Reverb block if I wanted, having both guitars share the same Reverb sound. So you can keep them separate with blocks affecting each guitar individually, then sum it later so both guitars share an effect if you want.

Global Blocks as an option

To help keep everything sync’d among my different presets, I use the Global Blocks feature new to the Axe-Fx II.  I set everything in my acoustic row (Mixer 2, GEQ, MBC, Enhancer, Reverb) to its own Global Block.  I want my acoustic sound to be the same on every single preset; it’s the electric sounds that change with my setup.  By using the Global Blocks, when I make a change to the GEQ on preset 4, the change will be saved to every other linked preset automatically. When I change to preset 2 for example, the acoustic will sound exactly the same even though I didn’t adjust anything specifically while in preset 2.  This was definitely a head-sore on the Standard and Ultra, but now it saves a lot of time and allows me to tweak my sounds more easily.

2 Amp blocks option

In my setup shown above, I happen to not use an Amp block for my acoustic tone. However, if your preset will always be using 2 separate guitars with a separate Amp block for each, you don’t need to use the Mixers. You can instead add an Amp block to Row 1 and another to Row 2 like normal, but then you must choose the appropriate Input on the ADV page of each Amp block.  Use Left for guitar 1 and Right for guitar 2.

You also need to select the correct input for Drive blocks on Page 3 of the edit menu:

Again, you must always use 2 Amp blocks as shown for this setup to work without Mixer blocks. It’s just another option and is easier to manage in some situations.

Volume blocks instead of Mixer blocks (Preferred Method)


Stringer76 at the forum brought up a great idea about using Volume blocks instead of Mixer blocks.  The Axe-Fx II offers 4 Volume blocks but only 2 Mixer blocks. I never needed to use Mixer blocks for any of my presets, so I decided to use them to split the signal. However, if you already use Mixer blocks in your patch, and/or have 2 spare Volume blocks, it’s actually easier to use.

Instead of placing Mixer 1 and 2 as described above, place Vol/Pan 1 and Vol/Pan 2 on the separate rows.

For Vol/Pan 1 – which is electric guitar – on Page 2, change the Input Select to Left Only.

For Vol/Pan 2 – which is acoustic guitar – on Page 2, change the Input Select to Right Only.

And that’s it! You have 2 more Volume blocks to use, and you have both Mixer blocks available for the crazy stuff in your head. I noticed no difference in tone, but the CPU usage is about .8 higher using Volume blocks vs Mixer blocks.  Shouldn’t be a deal breaker.


So that’s a few methods for “splitting the input” and using 2 different guitars with the Axe-Fx II.  Note that this setup has both guitars coming out of Out 1, basically sharing the same output. If you want the 2 guitars coming out of separate outputs, you should keep the rows completely separate all the way to the Output block (for example, don’t sum the rows to the Filter block as I did), and then Pan the rows in the Output block. Or you could instead have your electric row connect to the Output block (which is Out 1), and have your acoustic row connect to the FX Loop block (which is Out 2). Don’t put the FX Loop block in the very last column, as it will automatically connect to Output 1, which we don’t want. If you need to though, set the Level in the FX Loop block as low as possible.