I was looking at the new EVE Audio SC3070 3 way speakers at NAMM recently and started thinking about the benefits of 3 way vs 2-way monitors. Admittedly, I am no expert in the micro specifications of phase, time alignment, crossover slopes, driver efficiency, dispersion geometry, and cabinet design that go into differentiating the various models available. I come to our little universe from the vantage point of a musician rather than that of an engineer. However, in our collective world, I think we all need to be a little bit of both. So, I set out to try and educate myself. For those of you who, like me, scratch their heads when presented with obscure math symbols followed by units of measurements that require a science degree to understand, perhaps some of what I have learned will be useful.
When it comes to something as complex as a high-end studio monitor, common sense would suggest that simpler is better. 3-way monitors have more drivers and crossovers, as well as a bigger physical footprint to deal with. It seems to me like they have more potential to introduce problems with time alignment, phase issues, crossover ranges having “bumps”, etc. than simpler 2-way monitors.
So, I ask myself, if additional crossovers are bad then how can more crossover bands not negate the benefits of having a dedicated midrange driver? And if 3-way monitors usually have better bass because of bigger bass drivers, why don’t we find many 2 way designs using really big bass drivers as 3 ways do?
Here is what I have learned.
The main reason for multiple drivers in studio monitors is that different size speakers handle specific frequency ranges better than others. As an example, bass frequencies involve moving a lot of air, which is best served by a larger speaker. Higher range frequencies move air very fast. Vibrating at higher frequencies is harder to do with larger speakers, and works better with smaller sizes. 2-way monitors then, generally have a larger speaker for the low range (woofer), and a smaller one (tweeter) for the higher.
3-way setups include a speaker to handle the midrange. And as you would expect, they are generally somewhere in between the size of a woofer and a tweeter. Crossovers split the frequencies between the different speakers. Crossovers are typically set so that the ranges between the various speakers are tapered rather than stopping and starting at specific points. So, there is generally an area of the frequency range that is overlapping between the speakers.
For this to work, for the multiple speakers to blend and sound even and smooth, they need to be tuned and calibrated, so they each contribute a precise amount of output. Too much or too little from any of them will throw off the tonal balance by creating uneven responses in those areas of the frequency range covered by each of the multiple drivers. The crossover component plays a significant role in ensuring they all work together evenly. And they are harder to set up in a 3-way system than in a 2-way system.
So, is it better to split up the spectrum between 3 rather than two drivers? It depends. A combination of how well the crossover is setup, cabinet design, quality control in matching the speakers together, all contribute to the result. In addition to potential bumps in the overlapping frequency ranges, another potential problem with poorly designed crossovers is phase shift, which can cause problems at the crossover points in the frequency spectrum. So, a higher quality, better calibrated 2-way system will sound better than a mediocre 3-way system.
There is also the issue of time alignment between the multiple drivers. The more sources the sound is emanating from, the greater the potential for delay between them. Even a millisecond of delay might cause comb filtering in the crossover region. Well designed monitors take this into account in the angling and slanting of the drivers. But this also narrows the sweet spot for listening without any phase/timing/imaging issues. Generally speaking, 2-way systems are less complex to time-align than 3-way systems.
For these reasons, there's no getting around the fact that a good 3-way system will cost more than a good 2-way system. A less expensive alternative, however, is to get a good 2-way system with a subwoofer for bass. This set up creates a 3-way system optimized for bass. Filtering out the low end from the woofer leaves it to handle the mid-range more efficiently by not doing the hard work of moving the air for the lows. Having it do less work also reduces the potential for distortion.
But there are problems with 2-way speakers as well. With 2-way speakers, the tweeters, (usually 1 inch, so they can vibrate at a very high frequency), are less efficient at reproducing the upper midrange assigned to them. With a third driver dedicated to the midrange, each driver is responsible for a narrower frequency range, which results in greater efficiency and lower distortion.
A problem with crossovers in 2-way designs is that they are typically set in the 1 kHz - 3kHz range. This area of the midrange is critical for vocals and many instruments in a mix. All crossovers create some degree of phase distortion. With 3-way systems, the two crossovers are usually set outside of this critical range. So any phase distortions introduced, are in less significant ranges.
Back to EVE Audio and their new SC3070 speakers that I saw at NAMM. EVE Audio uses extensive DSP in all its 3-way monitors to optimize the performance of the amps, crossovers, and drivers. Their older SC305 model uses two 5” woofers and tweeter instead of a dedicated midrange driver for the third speaker. They have one of the woofers delivering sound only up to 350 Hz, functioning as a kind of "bass woofer."
The other woofer gives you a fuller range up to the 3000 Hz. So, it functions as a bass-midrange driver. This means less physical work for each woofer. And as a bonus, because two of these woofers are used simultaneously, you get an extended frequency response - down to 50 Hz. Add to this their rear rectangular bass port design, and you have an extremely efficient low range, meaning you can drive them harder and louder before distortion becomes a problem. Their bigger SC307 monitors are similar but are equipped with 6.5" instead of 5" woofers. They produce an accurate low end down to 40 Hz.
The EVE Audio SC3010/3012 monitors feature an even more efficient design, with a 10" woofer, a dedicated 5" midrange driver, and an even larger tweeter using their Air Motion transfer (AMT) technology.
But the newest member of the EVE Audio 3-way monitor lineup, the SC3070, combines the best of all their technology. They are compact midfield speakers, featuring a specially designed 4" midrange driver accompanied by a 7-inch woofer, and their RS3 tweeter. Their size hits the sweet spot for small to mid-size studios. They seem to be the “Goldilocks” monitors in their lineup. Not too small, not too big, not too expensive. They are just right. A nice size woofer, a dedicated midrange driver, and efficient well-engineered cabinet design.
So there you have it. There is no easy answer as to which is better between a 2 way or 3-way system. It depends on how well they are set up, and of course on your budget since 3-way speakers will cost more. At least now, hopefully, we are better equipped with the right questions to ask, and features to look at when deciding. And ideally, our collective head-scratching threshold has gone down a dB or two.