You may be wondering why we make such a big deal about the drivers in the Frontier Studio Monitors being time aligned. Is this all marketing nonsense and does it make a difference? Also, what does it mean? Is it electronic, or is it mechanical? This article will answer those questions, why the feature is important, and that it can make a very real difference in how you perceive your soundstage and accuracy of your mixes.
What is a Time Aligned Studio Monitor?
Time alignment is when the motor, or magnet--the acoustic centers--of different drivers are on the same plane, so the air being pushed starts on the same plane. The practical effect of this is that sound from each driver reaches your ears at the same time. If you have a two way monitor, that means sound from the tweeter and woofer get to your ears at the same time, making the drivers aligned in time.
There are ways to accomplish this electronically with the crossover, but this can open up a whole new can of worms (you can read about the Linkwitz-Riley crossover here if you really want to), and is a bit outside the scope of this article. However, the most consistent way of accomplishing time alignment is mechanically, and that's what we'll discuss.
A lot of studio monitors and speakers are not time aligned simply because mechanically, it’s more expensive in both parts and assembly. Also the added complexity of accomplishing it electronically without creating new issues and making everything worse can be difficult.
Most designs have the drivers mounted to the front baffle of the assembly, or the front panel of the speaker. Woofers, especially inexpensive ones, tend to be much bigger and deeper than the tweeters they’re paired with, with the motor of the woofer behind the motor of the tweeters. Therefore, sound from the tweeters will reach your ears before the woofer. Below 80Hz, this isn’t that big of a deal because we can’t really perceive direction below that threshold, but above it does become a problem.
Why This Matters
Sound obviously moves very fast, and you may be wondering how an imperceptible delay in sound reaching your ears matters. Well, there’s really nothing imperceptible, it’s a matter of how brains interpret the sound hitting our ears, and while our brains don’t interpret this delay, as well, delay, it does interpret it as a phenomenon known as lobe tilt.
In other words, the speakers fire down, so if you’re in what you think is the sweet spot, the sweet spot may actually be your chest, and finding this sweet spot by aiming your speakers up is kind of a fool’s errand because of it being inconsistent from speaker to speaker and cascading effects to acoustic treatment and everything else going on in your room.
This tilt will also change based on your EQ settings while mixing, so you'll effectively be moving your soundstage up and down while you EQ.
As you’ve likely deduced, this is bad, and will affect how your soundstage will translate to other systems.
Different Methods of Time Alignment
One method that we chose for Frontier while working with the brilliant Thomas Barefoot, was using a coaxial driver design where the tweeter literally sits in the back of the woofer. Other ways are using more shallow woofers or mid-range cones (in 3 way designs). Other manufacturers accomplish this by putting their tweeter on the back of a wave guide assembly, aligning the two drivers, or simply an odd shaped cabinet with the tweeter sitting back.
There’s also MTM, or D'Appolito designs (I worked on the M-Audio EX-66 early in my career, falling kind of in love with this design), where the tweeter sits directly in between the woofers. This ‘contains’ the vertical high frequency dispersion and tends to make for a very narrow dispersion–less frequencies bouncing off the floor and ceiling. Directionality and soundstage are usually excellent with these designs. Many THX certified speakers are variations of this because part of the certification requires limited vertical dispersion for accurate sound design playback. The downside is that these are usually huge for near field monitors, and sound bad if placed on their side (Two woofers and a tweeter isn’t a true D’Appolito unless the tweeter is directly in between, so this side weirdness doesn’t apply to monitors like the Barefoot Micromain 26.)
Conclusions
Hopefully you’ve gathered that this is not marketing snake oil, and that whether accomplished with the crossover or mechanically, this is not a feature to be overlooked if serious about the quality of your studio monitors or playback system.
