Using Left-Right EQ Technique for Problematic Recordings

The following tutorial will 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 your audio's left and right channels. You won't need to use this often, but it can be beneficial 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 elements of a full mix, including an acoustic guitar arp. Let's have a quick listen to it.

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

The original recording is not so good. A common practice is recording one guitar 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 and 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. We will use an EQ that supports left/right splitting to fix this, 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.

We can hear many more low frequencies and less high-end on the left channel, compared to the right track, which has more or less the opposite. To address this, we will add four bands to the EQ. We will limit the first band to the left channel to cut some of those low frequencies. The second band will also be concentrated 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 track to cut 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.

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

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