For Better Quality - The Classic Stereo Recording Techniques Series - Part 1

by Attila Tapolczai

Introduction

Technology, as with other human inventions (e. g. money or religion), is a double-edged sword. On one hand it enables us to achieve superhuman goals, on the other hand it easily becomes a fetish, an idol, endowed with god-like qualities, that we don’t understand but expect to solve all of our problems, thus hindering ourselves to use our own abilities.

Technology in audio recording is a similar beast. Today high-quality equipment is widely available to music artists who could use them to make recordings previous generations only had dreamed of. This equipment has user manuals too. The literature, the know-how, the mass of information about the mysteries of audio is greater than ever. Yet there is so much misunderstanding, so many myths around it, that we tend to forget how deep human understanding of physics along with art have shaped and improved audio technology. Unfortunately, musicians (and some engineers too) are too often obsessed with equipment instead of gaining more knowledge which could help them to make better recordings and save more money.

As an audio engineer and musician with more than 20 years of experience, I’d like to help you through this blog to understand a few basic things about recording, mixing and mastering, in the hope that human knowledge and art can take their deserved place back in the world of audio production.

In this article series I’m going to introduce some of the classic stereo microphone techniques that have been helping me to improve the sound quality of my recordings. In general, stereo miking of a sound source instead of mono can greatly improve recordings because of a more realistic representation of the original sound of any instrument. You can also make an instrument sound wider according to your taste or what the recording demands. I list the pros and cons of each technique and tell you how I use them, demonstrated with photos and short audio samples. 

 

The XY Array

Description

This setup consists of two identical cardioid microphones whose capsules are arranged in a 90-degree angle. The capsules are almost touching each other, they are basically at the same spot so it’s also called a coincident pair. There are several ways to achieve this as the pictures demonstrate below. A stereo bar (and an adapter) is of course very handy for most of these techniques. 

XY version 1

XY version 2

XY version 2 (front)

Application and Phasing 

To be honest, I’d been ignoring this setup for quite a while until I realized its strength and found its best applications, that are live recording and a solution for the infamous ‘singing guitarist’ problem. 

The biggest advantage of this technique is that you have little phasing problems which appear when a signal reaches two microphones in different times. To demonstrate this effect I recorded a stereo sample (with an AB setup), then moved one of the tracks in the DAW, intentionally causing phase cancellations (You can do the same by moving one of the microphones at the recording but it’s much difficult to get such a ‘pure’ result this way). Listen to the samples through headphones or good stereo speakers. What you'll hear is a very odd imaging, as if the music would come from between your ears or in your head. Unfortunately, this phenomenon appears even in professional recordings. 

Phase demo a) - in phase

Phase demo b) - out of phase

With the XY setup we don’t have such a problem because the microphone capsules are at the same spot so the signal arrives there at the same time but with different intensity due to the different directions. 

One disadvantage of this technique is that we have a somewhat narrow stereo image compared with other techniques. 

Placement

Notice carefully where the two individual capsules are pointing at and find the sweet spot for your instrument. Tip: Listening through headphones move the instrument around while you’re playing. I made two different recordings: one where the XY array is at the middle of the guitar with one mic pointing to the picking hand, the other to the neck, and one where the array is at the joint (where the neck meets the body). Listen to the two samples:

XY at the middle

XY at the joint

The Singing Guitarist

Recording a singing guitarist can be challenging because of the phase cancellations explained above, i.e. the blending of the two different signals (voice and instrument) into the other microphones. 

1. When the two mics for the guitar are too far from each other, like with an AB setup, this blending and phasing causes the image wandering unless it's set up very carefully. 

2. With two mono microphones this is less of a problem. But with a mono guitar recording we have an inferior sound. 

3. With the XY stereo array for the guitar and a mono mic for the voice, we can reduce this phase problem and still have a stereo sound for the guitar. Here's a song which I recorded with this setup. 

Lonesome Artisans - Don't Take Me for Granted (The Social Dist... Session)

Panning 

For panning the two signals I recommend anything between 50 and 90 for left and right. You can do 50-50, 90-90, 80-40, 20-70, depending on where you'd like to hear the instrument, how wide it should be or which spot you used for the recording (one signal is usually stronger than the other).

Pros and Cons 

Pros: 

• Superior to mono miking.
• No phase problems.
• Easy to set up (it's not difficult to measure 90-degree with the eyes). 
• It works well for live recordings and singing guitarists. 

Cons: 

• Stereo image is rather narrow (still better than mono).
• You need a pair of two identical microphones (at best a matched pair which can be expensive).