[Guest Post from Nathan Lively] Have you ever struggled to phase align your Main to your Sub?
There’s a reason for that and when you understand why, your sound system tuning is going to get a whole lot easier.
Phase alignment is used to align two or more speakers so there is a transparent transition between them. In short, you can’t tell where one’s frequency range begins and another’s ends.
PSA: This guide involves using an audio analyzer (Smaart, SATLive). If that’s a problem, now’s your opportunity to click away.
PSA#2: This is NOT a step-by-step guide for phase alignment. It is merely a collection of tips to help you get the job done with less stress.
The 3 Phase Alignment Hacks
#1 Place the mic close and low
Place your measurement microphone at the ground plane in the nearfield. You don’t have to put your microphone all the way on the floor since the wavelength of 100 Hz is 10ft, but getting close will remove the floor bounce. Then, measuring in the nearfield will drastically improve your signal-to-noise ratio (SNR) and should give you a nice clean measurement to work with.
Here’s the thing, if you’re measuring in the far field, you’re not measuring the Sub anymore. You’re measuring the room.
Subwoofers lack the directionality of a high-frequency driver so their sound goes everywhere. What you’re measuring in the far field is actually the average phase, which is a combination of the direct and reflected sound. This can make it very difficult to take useful measurements for a Main+Sub alignment and if you’ve ever tried to do this in a large room you’ve likely been frustrated.
Near field is the region close to the speaker where you’re dealing with direct sound, not indirect reflected sound. This enables the ability to notice detail and definition of the sound.
Far field involves hearing the sound source as it lives in the room, the feel of the room. As expected, this is found further away from the speaker.
#2 Put everything on the ground
If you can measure your Main+Sub on the ground before they go in the air, it’s going to make your life so much easier. You’ll still need to measure and verify the result once it’s in the air, but it will cut your struggle in half.
- No more floor bounce screwing up the measurement.
- Measuring in the nearfield improves SNR.
- Most speakers from the same manufacturer are designed to be phase aligned out of the box when they are grille-to-grille. If you can prove that that is true, then any future phase alignment in the far field can be done with a laser distance measure, saving you loads of time and headache. Ask me how I know.
If your speakers are not from the same manufacturer, it is still much easier to measure them on the ground. This will allow you to create a preset, which you can recall at each gig, and then simply adjust depending on the distance offset. Where you take the distance measurements for the preset adjustment will make a huge difference in how well your alignment performs over distance. This is a different exercise altogether and one I must save for a future post.
#3 Flatten phase trace
Reading phase is hard. I’ve been doing it for a while and I still think it’s hard. But you’re making it even harder on yourself by trying to read the phase graph with all of those wraparounds and steep traces.
Here’s what you do to make the phase graph easier to read around the crossover region:
- Measure Main in solo.
- Set the delay locator in your audio analyzer as you normally would.
- Add delay to the delay locator until the trace flattens at the crossover region.
Need more help?
I realize this article has probably raised questions for you. Here’s the good news: I’m not going to leave you out in the cold. How?
Introducing: ZOID, the sound system tuning chatbot.
ZOID is a chatbot I created to walk you step-by-step through a Main+Sub alignment. Not only will ZOID guide you through key decisions in the process, but he will also help you out with some calculations and even deliver a report at the end.
What can ZOID do?
- Create an overlap or unity crossover from scratch.
- Detect a polarity inversion.
- Suggest delay settings.
- Convert distance offsets into delay times.
- So what are you waiting for, meet ZOID.
- Or check out the video.
Thought? Questions? Comments?