Balanced Armature vs. Dynamic Driver

How often have you stopped to wonder how those earphones that came with your MP3 Player actually produce the music that you hear?

If you've ever been to an Electronics store, you've probably stumbled across the Home Audio section. There you'll see a wide array of speakers, all with different sound signatures and purposes. However, the technology behind these speakers are mostly the same--it's how the speaker transducer is designed and tuned that makes the drastic difference.

There are two dominating speaker transducer designs on the market. The most popular speaker transducer is the Dynamic Driver (also less popularly known as the moving-coil driver). Pictured below, a Dynamic Driver uses a permanent magnet which is attached behind the diaphragm, along with a voice coil (usually made out of copper), to push air rapidly at different frequencies.

A Dynamic Driver Transducer, pictured above, is the most common transducer design used in speakers today.
Source: WikiMedia Commons

Not to get into the nitty gritty, the Dynamic Driver has been a very popular design because of its ability to produce the entire musical frequency range (~20 Hz - 18,000 KHz+) with relatively good success.

Have you ever seen a speaker design different from a Dynamic Driver? Well, I would like to introduce you to the Balanced Armature transducer (often abbreviated as a "BA driver") , pictured below.

A Balanced Armature Transducer, pictured above, does not require external air to produce sound. This makes a BA Transducer much easier to tune to specifications.
Source: WikiMedia Commons

A Balanced Armature is very small--and I mean tiny. These transducers are often used in hearing aids for people with difficulty hearing. More recently however, they have gained popularity in premium in-ear monitors for consumers and musicians alike. The Balanced Armature transducer uses the same concept of a permanent magnet and a voice coil as a dynamic driver, but the one major difference with the Balanced Armature transducer is that it does not require external air to operate. A Dynamic Driver, on the other hand, requires an air vent in order to sound marginally good.

The benefit of this design on the Balanced Armature is that it can be tuned very precisely since external air does not factor into the equation. This means that midrange and treble can be much more accurate and detailed than that of Dynamic Drivers. However, the Balanced Armature design also has a large drawback: since it does not require external air to work its best, it lacks a convincing low-end response (bass response). This is often alleviated by combining several Balanced Armatures together, and putting them on a single crossover.

The JH16 custom in-ear monitor (a 16 Balanced Armature transducer) pictured above next to the Sennheiser HD800 (a dynamic driver headphone). The JH16 in-ear monitor uses a passive triple crossover to redirect portions of the audio input to their respective Balanced Armatures.
Source: Headfonia.com

What the crossover does is it splits the audio input into two or three (rarely more) frequency bands. This alleviates the problem significantly, as each Balanced Armature is now only responsible for handling a certain portion of the audio. A triple Balanced Armature in-ear monitor such as the EarSonics SM3 uses a single Bass Balanced Armature, single Midrange Balanced Armature, and single Treble Balanced Armature. This changes the response of the in-ear monitor significantly, and the bass response becomes much more realistic and natural.

After having heard Dynamic Drivers for many years, I tried a Balanced Armature in-ear monitor (the Shure SCL4), four years ago. The midrange was impressive, but the in-ear monitor lacked bass and a realistic treble. I then upgraded back to a Dynamic Driver (the Sennheiser IE8), which made me miss the detail retrieval of the Shure SCL4.

It was then that I knew that something about the Balanced Armature transducer made music sound all the more better. So I upgraded again to a Triple Balanced Armature in-ear monitor, the EarSonics SM3. This in-ear monitor made me a true Balanced Armature fan, as it eliminated nearly all of the problems that I had heard with the Shure SCL4 (due to three Balanced Armatures instead of one).

After a year with the in-ear monitor, I wanted even more quality. So I decided to purchase a custom in-ear monitor (required an ear impression from an audiologist): the JH Audio JH16. With 8 Balanced Armatures in each earpiece (4 for lows, 2 for mids, and 2 for highs--for a total of 16 speakers with two earpieces), I have never heard such quality produced from an audio device in my life.

Don't ask me how much it cost me though! (You don't need to spend much to enjoy the sound of a Balanced Armature!)