Fake Guitarist

I've loved Leonard Cohen's song Hallelujah for a really long time.  Lately, I've been toying with the idea of doing a cover version.  More on that in the future, perhaps, but my experimentations in this area have led me down a path where I did some interesting things with the new Midi Effects introduced in Logic Pro X.  I thought I'd write about it. 

First off, here is the result.  It's made from the four bar intro, verse and chorus to Hallelujah - no vocals, just fake guitar and drums.

What I find surprising about this, and the reason that I'm writing about it, is that the whole guitar performance in that 58 second track is driven by just 26 midi notes.  This was entirely achieved using the Midi Effects, which are the green blocks that you can see in the channel strip screen capture on the right.

I started off with a project set in 6/8 time at 101bpm, and loaded the first channel strip with the library preset British Stack Synth Lead.  As you can see from the channel strip, this uses the Sculpture modeling synth, included with Logic, to make the guitar sound which is then processed through a bunch of Logic's guitar effects, a delay, a Channel EQ, and a compressor.

Chord Trigger

First off, I loaded a Chord Trigger.  This allows you to map single incoming midi notes to multiple outgoing ones - in simpler terms, pressing one key on your midi keyboard produces a chord from your software instrument.  Exactly which key produces which chord is entirely configurable.

There are a number of presets, but to aid understanding I decided to make my own using the chords of the C major scale.  So, the chords were C major, D minor, E minor, F major, G major, A minor, B diminished, and a further C major at the top of the octave.

Here is a screenshot of the Chord Trigger module, showing the chord produced by an incoming C2 from the midi keyboard. 


Chord Trigger, showing C2

I clicked "Learn", then the note on the "Input" keyboard, and then all the required notes on the "Output" keyboard.  Finally, I clicked Learn a second time to finish working on that input note.

After programming all eight notes, I saved the results as a new preset, and set about recording the 26 midi notes that would cause the Chord Trigger to play the chords for Hallelujah in the key of C major.

Hallelujah, in 26 notes. 



Leonard Cohen wrote Hallelujah in C major, but it turns out that I can't sing it in that key (or in any other key, some might argue!) .  A♭ major suits my range better, it seems.  

I first added the Transposer before the chord trigger, but that meant that transposed notes would often fail to hit the narrow single octave range that I had programmed in the chord trigger.  Much simpler to transpose the output of the chord trigger.

Shown to the right is the Transposer, configured to transpose down four semitones from C major into  A♭ major.

The transposer has all sorts of extra functionality that lets you switch notes on and off, and other clever things, but I just used the slider at the top for simple transposition.

So far so good.  Now for the real fun, with the Arpeggiator.


Here's the arpeggiator, configured to turn the chords coming out of the transposer into the guitar part that you heard above. 


The main configuration here is in the Pattern panel at the bottom, and the Note Order panel above it.  Firstly, I configured the arpeggiator to play 1/16 notes.  As my version of Hallelujah is set up in 6/8 time, this meant that there are 12 arpeggiator notes to the bar.   Arpeggiator will do patterns of up to 128 steps, but I restricted it to one bar of 12 notes by dragging the pattern length selector below the pattern grid.

Following some experimentation, I selected the "Outside-In" note pattern with a two octave range.  I also selected variation 4 to start with, but then I changed it.  More on that in the section on Automation below. 

I then experimented with the heights of the velocity bars, and changed some of the notes of the arpeggio to chords.  I think that this last step was the key to getting the result to sound semi realistic.  The inclusion of some chords among the notes of the arpeggios sounded much more like something a real guitarist playing something like this might do. 


I then added a Drummer track.  Logic Pro X's virtual drummer is very impressive - this one used pretty much the default configuration for "Kyle" (yes it does feel a bit weird that they have names) and it sounds to me like a real drummer.

To help Kyle understand the structure of the song, I created an Arrangement track which explains to him which bit of the track is which.  The Arrangement track is revealed (along with Marker, Signature, and Tempo tracks) when you click the button at the top right of the track headers in the Arrange window (indicated in the screenshot to the right).

In the arrangement track, I designated the first four bars as "Intro", the next sixteen bars as "Verse", and the final nine bars as "Chorus".   You can hear the character of Kyle's drumming changing between these if you listen again to the track above.


Finally, to break the guitar part up a bit, I used automation on the main track in Logic to alter the "Variation" parameter in the Arpeggiator.  The intro is variation 1, the verse is variation 4, and the chorus is variation 3.  It's not a huge difference, but you will be able to hear it if you listen again.

Guitar track, showing automation.


In summary, I was surprised and pleased by what I was able to achieve with the midi plugins.  I don't think that this particular sound is right for any Hallelujah cover, but it could be right for any number of other song projects.   I'm looking forward to further experimentation.