A recent assignment in one of my Berklee guitar classes inspired me to dial in my Wall of Guitars sound.  You know, the sound of an army of guitars that has you surrounded. This effect is typically achieved by mixing together multiple takes (sometimes with different amps and guitars) and the slight variations in timing and pitch combine to create a thick, immersive sound.

But, who has time to double- or triple-track everything they record, and switch up their gear between takes?  Wouldn’t it be great if you could get a similarly massive sound using a single take?  With a few tricks, you can!

Listen to the before and after tracks below and read on to see how the effect was achieved.

Before (single guitar track): 

After (with “wall of guitars” process applied): 

Source Material

You may be surprised to learn that the processes started with this clean guitar track:

Source Guitar : 

The amps on this page are Logic Pro X software amp simulations.  Here is that same guitar track running through an amp model:

Single Amp: 

That sounds pretty good but the (mono) guitar is sitting right in the middle of our mix, competing with our bass guitar and kick drum, and it sounds rather small.

Multiple Amps

The core of the “wall” sound is having two amps running in parallel.  In my home studio, I use a Radial Switchbone AB/Y  to run a guitar to two amps at the same time.  You can get the same result using multiple software amp models – which is what you are hearing on this page.

A feature of using software amps is the ability to re-amp your tracks, or, go back at a later time and switch amps even after you’ve recorded your guitar tracks.

Here is that same clean guitar track run through two different amp models, each panned to one side:

Parallel Amps:

This is a nice wide sound, and you can distinctly hear the two different amps.  However, each ear is getting a slightly different tone – if your amp settings are different enough, this will create an unbalanced sound.

The Haas Effect

I learned a number of great audio engineering techniques from the book Mixing Audio by Roey Izhaki. I highly recommend this book if you want to learn how to improve your mixes.

One of the techniques covered in the book utilizes the “Haas Effect”, also known as the “Precedence Effect”. The idea is to pan a signal to one side and then pan a slightly delayed “ghost” copy of it to the opposite side. The result is a signal that appears to originate from the non-delayed side but fills the stereo field (since it is actually in both channels).  Here is the Haas effect applied to our single-amp track:

Single Haas: 

Can you tell which side has the “ghost” signal?  Even though we can hear the delayed “ghost” in the right channel, we get the impression that the guitar is on the left side since the left channel is not delayed.

We’ll use this technique to get the sonic qualities of both amps in each ear while still giving the impression that we’ve panned the amps to opposite sides:

AMP 1 : non-delayed in L, 30ms delayed in R (-2dB)
AMP 2 : non-delayed in R, 20ms delayed in L (-2dB)

Choosing slightly different delays for each channel thickens the sound, and I find that dropping the “ghost” signal by a few dB sounds good. Here’s the result:

Parallel Haas: 

That is a nice even guitar sound that has a super-wide stereo field. However, why just do it when we can overdo it! Let’s tweak it a bit more…

Pitch Shifting

In a multi-tracked recording, there are slight variations in pitch and timing in the various guitar takes. So, in our quest to sound like a multi-tracked guitar session, let’s add some slight detuning to our “ghost” signals:

AMP 1 : non-delayed in L, 30ms delayed, detuned +10 cents in R (-2dB)
AMP 2 : non-delayed in R, 20ms delayed, detuned -5 cents in L (-2dB)

Parallel Haas + Pitch Shifting : 

It’s a subtle effect, but the pitch shift thickens the sound.

Final Touch

The final touch is to add a bit of reverb to the guitar mix to tie it together. In this case, I’ve added a bit of room reverb to all four signals:

Final Result: 

Sample Project and Video Walkthrough

I’ve attached the Logic Pro X project for the tracks on this page and a short video that goes through the steps described above.  Take a look through the Alternatives in the project to see the project at each step in the process.

Sample Project for Logic Pro X : Wall of Guitars_v2.logicx