Editor’s Note: This is an extremely belated writeup; for various reasons, it was continually delayed in lieu of other content. The author apologizes profusely for the long wait.
For quite some time, Class D amplifiers were thought of as the ogres of the solid state world. Audiophiles found them repugnant, dastardly little digital devices. However, the speaker industry sought them out as purveyors of driving efficiency, and have since developed all sorts of high-end amplifiers utilizing advanced Class D amplification circuits. Despite these advances to Class D amplifier development, those of us in the headphone world have still eschewed Class D. They’ve been accused of being wonky in the treble, sounding “unnatural”, amongst other things — giving most of all Class D headphone amplifiers a fairly bad name. The only Class D amplifier to really gain a good reputation amongst headphone audiophiles was the iQube, and that was ages ago (in audiophile time scales).
There’s a new kid on the block, however, and JL Acoustic Labs is ready to reinvent the ‘digital amplifier’ name. I recently purchased their BAB1-MC *LE Edition #L. If that’s not already a mouthful for you, then get ready for its description: it’s an “ADA/DDA digital sound amplifier with sound field control.”
Wait, what? Yes. There’s a reason why the BAB1 isn’t merely called a headphone amplifier. It is neither Class A, Class AB, nor purely Class D. It does, however, share most traits in common with a Class D amplifier, such as high efficiency. The battery life is rated at 300 hours and I’ve never even felt this device get remotely warm to the touch. Instead of operational amplifiers, vacuum tubes, or switching capacitors, the heart of the BAB1 is populated by a single multicontroller unit (MCU) used specifically in digital sound processing for broadcast audio/video applications.
Then there’s the actual application of this MCU — inside the BAB1, there are all sorts of clever DSP methods, the principles of which I can’t quite explain adequately. First, there’s “Sound Field Control”, in which signals in the frequency domain are separated into low, mid, and high frequencies, and processed independently in the amplification process. Then, there’s the actual act of doing the pulse modulation from the digital domain to analog. All of these things are performed by one single chip.
Technically, JL Acoustic Labs didn’t reinvent the wheel. The idea that a microcontroller unit can be tapped to perform a myriad of amplification and DSP duties has been outlined by many an audio designer and DIYer. However, no one has ever come up with a consumer product that actually uses this design, until now.
The outward appearance of the BAB1 belies its high-tech guts, however. The case itself is of a generic variety, similar to the case used in the Just Audio µHA-120 or MH Audio HA-1 — not going to win any beauty contests. The bump stops, clad in plastic, are not exactly the paragon of build quality, and neither are the metal faceplates enameled with a heavy labeling sticker. However, it’s adequately appointed, and everything is simple to operate. When it comes to usage, the BAB1-MC is as simple as plug-and-play. There’s no gain switch and no bass boost (I’ll leave it up to you to decide whether that’s a good or bad thing).
So why the simpleton features despite a complex interior? I started wondering why JL Acoustic Labs would adopt a Class D design in the first place — when it comes to smaller scale audio companies, I find that understanding the owner reveals a lot about the company’s interests, strengths, and style. Mr. John Lee, founder of JL Acoustic Labs, is a longtime audiophile with many different interests; he started up the workshop more as a hobby to research better things for him to personally use during his business trips around Asia. (He also builds cables, metal-cast earbuds, and BA IEMs.) Mr. Lee’s day job is of a real estate developer and thus requires him to jet around the Pacific from his native South Korea. Hence, John needed something that was both portable and long-lasting to use during flights. It began to make sense how efficiency is a priority for the BAB1 — one two-hour charge from the mini-USB port at the back, and you’re ready to rock and roll for two weeks straight (that’s given that you sleep for ~5 hours a day, and listen to music for the other 19 hours — already pretty ridiculous).
So what of the sound? Is this the portable Class D revolution we’ve been looking for?
Well, I’m not quite sure how I cajoled Mr. Lee to let me purchase a BAB1 amp, but I’m glad I did. The BAB1 has perhaps the most pronounced sense of imaging and layering in a portable amplifier that I’ve ever listened to. The effect is absolutely glorious, and it most definitely proves Shrek’s point that ogres aren’t merely one-dimensional Class D abominations — like an onion, they too have layers!
The device seems to enhance the imaging characteristics of any headphone or earphone that I use it with, whether it be my HIFIMAN RE-262 or Sennheiser HD598. I suppose it’s the “sound field control” doing its thing, but it definitely allows music to feel very, very transparent and detailed. Because of its digital design, the BAB1 should have inherently low output impedance; bass always feels very well damped, even with balanced armature drivers. The result is an incredibly separated, but coherent sound that allows full appreciation of the variegated musical elements within a track.
There are two issues with the BAB1 — the first is hiss, which is noticeable from the moment the amplifier is turned on. If you’re using low-impedance IEMs, then you will pick up hiss on this amplifier. High-impedance IEMs like the Etymotic ER4B or HIFIMAN RE-262 fare much better, though not completely immune. Hiss is apparently an Achilles’ Heel of almost all Class D type designs because of high feedback loop gain, and unfortunately the BAB1 does not do away with this problem. People who hate hiss should avoid this amp at all costs.
The second issue is the high-frequency extension. The amp just doesn’t seem to have the best extension in the highs. Every single digital amplifier requires a low-pass filter built-in (hence why there are two massive Mundorf capacitors in the interior of the amp). The limitation of an MCU implementation is that the rate of pulse modulation also needs to be programmed by hand. Mr. Lee told me that he spent a lot of time measuring a wide range of headphones and earphones so that the low pass filter would be an optimal fit for most earphones and headphones, though I always felt that there was a bit of extra extension that was tempered down by the filter’s soft elbow, at least compared to other amps that I’ve heard. The sense of “air” is just not quite pronounced with the BAB1. However, the upside of this effect is that the amp’s sound feels very solid and grounded; with its excellent imaging and separation, the BAB1 never felt cramped, as some amplifiers can become if designers purposely roll-off the highs.
The shortcomings of the BAB1-MC will likely still drive away the conservative audiophile; yet, I’m still very glad I purchased this unit; it’s just a very unique entity in the portable domain. Its sound quality is excellent. The battery life alone is a big win. The geek in me also feels fascinated by the programmable characteristics of the BAB amplifier. Theoretically, any headphone could be driven optimally with a custom-programmed BAB1. Mr. Lee even had a special 20-unit run of the BAB1-BP *LE filtered exclusively for the Rooth LS8+, so the possibilities are pretty much endless.
So yes, like an onion, there are parts of the BAB1 that can make you tear up a little, but mark my words: this little device is no ogre. With a little bit of the right accompanying ingredients, like a brighter, higher-impedance IEM, this little onion can possibly make your audio salad perfect.
- Extremely impressive sense of transparency and soundstage imaging
- Great transducer damping control with both low and medium (<150 Ω) impedance headphones
- More powerful than expected; can drive full-sized headphones, e.g. Sennheiser HD600
- Loud basal levels of electronic hiss
- Gain slightly high for low-level listening with sensitive IEMs
- Less “airy” sounding compared to other top-level portable amps, e.g. Firestone Audio Fireye HD, Triad Audio L3
- Note that the version displayed here on CYMBACAVUM is different from the retail version distributed by Zionote and sold in stores such as e-earphone. The retail version in Japan is named the BAB1-XA and utilizes a different filtering scheme from the BAB1-MC *LE.
- There is also a BAB3-JE, which uses a dual-core MCU over the single-core BAB1 and has better output power.
- Also note that the BAB series of amplifiers is not currently for sale outside of Japan and South Korea; JL Acoustic Labs is currently in talks for worldwide distribution.
- JL Acoustic Labs has been working on a balanced amp as well; their Japanese distributor Zionote showed off a prototype version for the Fujiya-AVIC Tokyo Headphone Show. Read about it in our post-show report here.
For more information on the BAB1 and other JL Acoustic Labs products, please visit the Japanese distributor Zionote‘s product page.
Photographs can also be found on CYMBACAVUM‘s Facebook page here.
Special thanks to Mr. Lee for being such a great guy to communicate and chat with!
Mr. T is an in-ear fanatic by day, and writes SOAP notes by night. He pities the fool who actually has the patience to read through his stuff. (Full Author Bio)