It’s an age-old question if 15-inch speakers are really that better than 12-inch. Is it just a marketing trick to make the buyer go with the logic “bigger is better”?
A decent number of people will go with 15s if they lack a subwoofer, thinking that it can substitute one. Or they’ll buy a pair of 15s, thinking they will be louder than a pair of 12’s.
So what’s the deal here? Are things actually that simple?
A 12-inch speaker is generally better because although it only has one driver for highs, the second driver is only trying to produce mid highs and mids, with no low end. Speaker drivers perform best when they’re performing specific frequencies. 12’s sound better, cost less, and produce the same volume.
Not to mention, a 12-inch driver produces the mid highs significantly better than a 15-inch driver because the 12 inch is smaller and easier to move. This is a big reason why you’ll never see 18 inch two-way top speakers. All the problems with a 15 inch top would only be worse.
The Electro-Voice ELX-200 stands out as one of the best 12″ tops that can easily compete with 15″ tops in the bass.
But without further ado, let’s dive into the differences between 12 and 15-inch speakers.
There Isn’t Much Difference In Bass Between 12″ and 15″ Speakers
You honestly won’t get much more deep bass from 15″ tops than you would with 12″ tops. I would personally grab a pair of decent 12″ tops and add subs as needed.
The 15″ driver in a top does not work like a 15″ sub – the driver is different, and the cabinet is not designed for the sub-bass. Also, most speakers use the same voice coils and motor assemblies for their 10, 12, and 15-inch versions.
Sure, manufacturers throw in their ‘Bass Reflex’ ports, but those are mostly window dressing.
It isn’t an exact equivalent, but think of three cars with the same engine but come in 3 different sizes: one weighs 3000 lbs, another weighs 3600 lbs, and the third weighs 4500 lbs. While our instinct tells us the biggest car would be the strongest, the reality is that the motor will be more effective at driving the smaller car than the larger cars.
To compound that fact, the cabinet size needs to be a lot larger for larger-sized drivers, although they make the consumer cabinets just large enough to hold the driver to keep things compact. So the cabinet for the 12-inch driver will be closer to optimal size than the cabinet for a 15-inch driver.
A 15-inch speaker can’t replace a subwoofer.
You won’t ever feel the bass just from having 15s, don’t listen to what anyone says. You only FEEL the bass from a sub, or two, or four… depends on room size.
A 15 inch two-way only has one driver for highs and then one other driver to handle all the mid-highs, mids, low mids, and then people also try to push bass through them. It just doesn’t work.
12-inch Speakers Usually Have a Better Quality-Price Ratio
When you look at the price, 15’s are, in most cases, kind of overrated.
15-inch PA speakers are not much louder than 12’s, they don’t have mids much better than 12’s (sometimes worse), and they don’t provide enough low end to replace having a sub. They’re heavier and more expensive.
There are very few situations where you would ever really use the 15s correctly. When you don’t need/want a sub, most 12’s produce enough low end to just be heard but not felt like a sub. If you had 15s instead of 12s, the low end might be heard a little more clearly, but it would just make the mids and highs overall quieter and subdued.
The majority of times, a 12″ speaker will sound better than a 15″ regardless of how good that 15″ top is. A 15″ top will be more versatile than a 12 since you can use it on its own and produce a bit more bass standalone that it’s adequate.
To be honest, I can’t really think of a time I would ever recommend having 15s over 12s. Except for maybe the odd party where for some reason, I don’t want a sub, but I still want to be able to hear “low end,” but I also don’t really want to hear mids or highs as well.
A 12-inch PA speaker, on the other hand, will seriously help the sound travel farther than with any 15-inch speaker AND sound way better.
Three-way 12s sound better and make the sound travel farther because they have a dedicated driver for highs, dedicated for mid highs, and dedicated for mids and low mids.
These portable 12″ JBL PA speakers have waaay better price-quality ratio than most 15” speakers!
12-inch Speakers Make Sound Travel Farther
The 12-inch speaker will make sound travel farther because the dispersion of the sound is entirely different on most of them. Most standard 15-inch speakers will disperse sound 90 degrees horizontally and 60 degrees vertically.
This wastes energy and causes a variety of other acoustic problems. The 60 vertical degrees means that almost half of your vertical coverage is just going up to the ceiling over everyone’s heads and causing reverb.
Then you have to turn it up, which also makes the reverb louder. Not so good. Then, your 90 degrees horizontal is traditionally way too wide.
This causes comb filtering, and listeners are usually not spaced out that much. You want venues that are long, not wide. So again, your sound is going out away from the crowd causing you to lose volume and create reverb.
While the coverage issues are still not entirely removed (you would need a subwoofer for that), it is significantly better. Plain and simple, you’re aiming more of your volume towards the listener.
When Paired With Subs, Are 12-inch Still Better?
15s aren’t much louder, don’t help the sound travel, and sound generally worse than 12s, especially when paired with subs.
Pairing 15s with a subwoofer is not optimal because you’re going to want to crossover your speakers/subs so that you don’t have your 15s trying to make the low frequencies that the subs are also trying to make.
So then your 15-inch speaker is just trying to replicate a woofer. Pointless.
When pairing with subs, if you put 12s to hang, you won’t have dispersion issues because they’re hung up high and then aiming down directly at the listeners. Then you don’t have sound bouncing off the walls or ceiling anymore.
15s are larger and heavier, and it’s hard to hang them.
I’m strongly in favor of just getting 12s and subs.
Are 15-inch Speakers Louder than 12?
The simple answer is no. However, this detail is a matter of other specifications of specific speakers. But if all specs are the same, the size of the speaker doesn’t make it louder.
Speaker size has no bearing on loudness because the sound is mechanical energy derived from motion. An extra speaker, for example, would increase the volume. When you add a second speaker, you have two pistons moving at the same air pressure. The more air that moves, the louder the sounds become, and the sound intensity doubles.
However, doubling the speaker box does not imply doubling the decibels. This is due to the way decibels are calculated.
Decibels are magnitude-measuring logarithmic functions. Every ten-decibel increase increases the audio’s intensity tenfold. A 60-decibel sound has a power of 1,000,000 times (106) that of a 1-decibel sound.
More size, on the other hand, does not add any decibels to the equation. The human ear requires a 10-decibel increase to hear twice as much audio. Why?
Psychoacoustics, or how one perceives loudness, is concerned with perceived loudness. The perception of sound differentiates from person to person. Even so, evidence suggests that humans double their loudness every ten decibels.
This means that to hear twice as loud, you must increase the sound intensity by a factor of ten.
The loudness rises in a linear fashion. You’ll get double the previous sound for every 10-decibel increase in volume. 60 decibels, for example, will double in volume when it reaches 70 decibels. This sound is four times as loud as 60 dB once it reaches 80 decibels.
This means that 100 decibels are equal to 16 times the loudness of 60 dB.
What to Consider When Deciding Between 12 and 15 inch PA Speakers?
Something to consider when buying PAs is not just the RMS rating (which companies will often overrate as a marketing tactic) but the speaker’s frequency range because this is more indicative of how well it will perform and the quality of the components built with.
All power ratings for anything but the most professional level touring gear is severely overrated.
For example, 15-inch QSC speakers are not even approaching 2000 watts in real-world use. It’s just become another marketing number that companies use to influence uneducated buyers that think wattage = loudness.
I did a power draw test on my setup, and I’m pulling about 8 Amps (1000 Watts) with two EV 12s rated 1000 Watts each and an EV 15 sub rated at 1300 Watts.
Here’s the Amazon link for the speakers I own – Electro-Voice ZLX-12P.
This is similar to buying a shop vac or an air compressor rated for 5HP or more. A single 15 Amp household circuit will only handle 1800 Watts – less than 2 1/2 HP. Those “peak power” ratings are last for about 100 milliseconds when the motor locks up and the breaker trips.
I don’t even think they are truthful peak numbers. The amp might be rated at a certain wattage, but they are often limited at way lower because the drivers cannot handle that much power without blowing.
A more accurate spec for overall volume handling would be the max SPL, but even those are usually half-truths if not straight-up lies as well – and those are most definitely peak numbers.
For example, the 15-inch speaker is listed at 132db when it usually only hits around 100 dB before the limiter kicks in real-world measurements.
It also doesn’t take into account the efficiency of the amps and drivers where a more efficient speaker could utilize that wattage to produce more volume than something that isn’t (see Behringer’s ridiculous “3000-watt” sub that only maxes out at 129db SPL).