A Simple Test to Check Speaker Phase

Do you notice the sound of your studio monitors changes when you move your head? That subtle, unsettling shift—maybe your highs disappear or the image collapses—is a major clue. Before you reach for another EQ plugin, consider the true foundation of your mix: your speaker placement and phase. Even a few millimeters of difference can wreak havoc on your stereo image and overall clarity.

Today, we’re going to explore a simple, yet effective, test you can do right in your own studio to check if your speakers are truly in phase with each other. And then, we’ll dive into how to precisely measure and correct any issues.

The Head Turn Test: A Quick Diagnosis

This test is remarkably simple and requires nothing more than your ears and your favorite reference track.

1. Set the Scene: Sit in your usual listening position in your studio.
2. Choose Your Weapon: Find a piece of music with clear, clean high-frequency content. For this, I highly recommend the drum intro to Dave Brubeck’s “Take Five” on a loop. It’s got fantastic transient detail and crisp highs.
3. Go Mono: Sum your audio to mono. This is crucial as it ensures the sound is coming from a single, perceived point directly in front of you.
4. Listen and Turn: Play the music at your usual monitoring level. Now, very slowly turn your head towards one side wall. Continue turning until you are looking straight at the side wall.
5. What to Listen For: As you turn your head, pay close attention to the high frequencies. If you notice a loss of high frequencies – a smeared, dull, or less defined sound – by the time you’re looking at the side wall, then your speakers are likely out of phase with each other.

What does “out of phase” mean in this context? It means one speaker is slightly closer to your listening position than the other. We’re talking millimeters here, but those tiny differences cause sound waves to arrive at your ears at slightly different times, leading to phase cancellation and a degradation of your high-frequency response.

Get our Studio Calibration Suite. 100% Free! No sign up! No Catch!

Taking it Further: Precise Measurement with REW (Room EQ Wizard)

While the head-turn test is a great initial indicator, for precise diagnosis and correction, we turn to tools like REW (Room EQ Wizard). REW is a powerful, free acoustic measurement software that can give you incredibly detailed insights into your room and speaker performance.

What to Look For in REW:

1. Impulse Response: This is your holy grail for phase and timing.
   • How to Get It: You’ll need a measurement microphone (like a MiniDSP UMIK-1 or. behrin) and REW set up to take measurements. Place your microphone at your listening position. In REW, generate a sine sweep, record it, and then analyze the impulse response for each speaker individually.
   • What to Look For: In the REW “Impulse” graph, you’ll see a sharp peak representing the initial arrival of sound from your speaker. You want these peaks for both your left and right speakers to align as closely as possible.
     `http://googleusercontent.com/image_generation_content/0
2. Delay/Timing Offset: REW can also calculate the delay difference between your speakers.
   • How to Get It: After taking individual impulse response measurements for your left and right speakers, REW’s “Align LR” or “Generate Group Delay” functions can show you the precise timing difference in milliseconds.
   • What to Look For: Ideally, you want this difference to be as close to zero as possible. Even a fraction of a millisecond can be audible.

Physical Measurements: The Foundation of Accuracy

Before diving deep into REW, or even after identifying an issue with the head-turn test, getting out a tape measure and physically measuring your speaker placement is crucial. This helps you identify the cause of any timing differences and provides the information needed to correct them.

1. Speaker to Listening Position:
   • Measure the distance from the center of the tweeter of your left speaker to the center of your head in your listening position.
   • Repeat for your right speaker.
   • These two distances should be identical. This forms the basis of your equilateral triangle (or near-equilateral, depending on your setup).
2. Speaker to Front Wall (Behind Speaker):
   • Measure the distance from the back of your left speaker to the wall behind it.
   • Repeat for your right speaker.
   • Again, these should be identical. Any difference here will affect early reflections and potentially your low-end response.
3. Speaker to Side Walls:
   • Measure the distance from the side of your left speaker to the nearest side wall.
   • Repeat for your right speaker (to its nearest side wall).
   • While not as critical for phase at the listening position as the front-to-ear distance, equal side wall distances contribute to a balanced stereo image and prevent unwanted asymmetrical reflections.

Correcting the Discrepancy

Once you’ve identified a phase issue, either by ear or with REW, the correction often comes down to precise physical adjustment:

• Move the Speaker: The most straightforward solution is to carefully adjust the position of the “further” speaker until its distance to your listening position matches the other. Use your tape measure and keep checking with the head-turn test and REW.
• Speaker Stands: Invest in good quality, adjustable speaker stands that allow for precise height and depth adjustments.
• Decoupling: Ensure your speakers are properly decoupled from your desk or stands to prevent unwanted vibrations that can muddy the sound.

The Payoff: A Clearer, More Accurate Sound

Taking the time to ensure your speakers are perfectly in phase might seem like a small detail, but the impact on your mixing can be profound. You’ll notice:

• Improved Stereo Imaging: Your instruments will have a clearer, more defined place in the stereo field.
• Enhanced Detail: High frequencies will sparkle with greater clarity and less smear.
• Better Translation: Your mixes will sound more consistent across different playback systems.
• Less Ear Fatigue: A more accurate sound can reduce listening fatigue during long sessions.

So, next time you’re in your studio, give the head-turn test a try. And if you suspect an issue, don’t hesitate to break out REW and your tape measure. Your ears (and your mixes) will thank you!

Leave a comment below if you have any questions or to let us know how you get on with your speaker phase alignment!