In the next tutorial, we’ll discuss an instance where you can use the left-right EQ technique to fix an otherwise problematic recording. This means using an EQ with independent curves for the left and right channels of your audio. You won’t need to use this often, but it can be very useful when you work with acoustic guitar, synths, or recorded keyboards, where stereo technique recording is commonplace.

As usual, we have prepared a short sequence in our SoundBridge: DAW. It contains most of the elements of a full mix, including an acoustic guitar arp. Let’s have a quick listen to it.

SoundBridge. Left-Right EQ session
~Full Mix – Unprocessed AC. Guitar

The center melody of our sequence is the acoustic guitar arpeggio, which can probably sound better. Let’s listen to it solo first.

~Ac. Guitar – Unprocessed

The original recording is not so good. A common practice is for one guitar to be recorded with two microphones, one on the body and the other somewhere over the guitar frets. This is the case here. The issue is that these recorded signals have been panned to some extent, somewhere between 60 or 70%. Because of this, we hear lots of bass on the left and more high-end focus on the right, so the guitar doesn’t sound unified. In order to fix this, we will use an EQ that supports left/right splitting, as most modern EQs do. In our case, we will use the FabFilter Pro-Q3. Let’s drop a new instance of it on the acoustic guitar channel.

Left-Right EQ for an acoustic guitar

After opening the FabFilter Pro-Q3 interface, we will navigate to the bottom right section, where the main output control is located. By turning the upper part of the knob we can isolate the left and right channels. Here is what can be heard on both.

Fab-Filter Pro Q3. Left-Right EQ session
~Ac. Guitar – Left Channel
~Ac. Guitar – Right Channel

We can hear that on the left channel there are a lot more low frequencies and less high-end, compared to the right channel which has more or less the opposite. To address this, we will add four bands to the EQ. The first band we will limit to just the left channel, to cut some of those low frequencies. The second band will be concentrated also on the left channel but to boost some high-frequencies with a high-shelf filter instead. Next, the third band will be limited to the right channel, for cutting some of the high frequencies, again by using a high-shelf. Finally, we will boost some mid-range frequencies on the right channel around 600 Hz.

Left-Right EQ settings

Now it’s time to check how our acoustic guitar arpeggio sounds before and after processing.

~Ac. Guitar – Unprocessed
~Ac. Guitar – Processed with Left/Right EQ

Lastly, let’s listen to the processed acoustic guitar arpeggio in the context of the full mix.

~Full Mix – AC. Guitar Processed With EQ