Thread: 64Audio A18T - Flagship Custom In Ear Monitor. A Speaker Lover's Monitor

Part 1

Over the past few months, since the first week of March - to be exact, I have had the pleasure of listening to the 64Audio A18T custom in ear monitor (CIEM). This CIEM is the 64Audio flagship, a brand used by many well recognized artists and sound engineers, and packs in a whopping 18 drivers per earpiece: 1high*, 1high-mid, 8mid, 8low. Driver count, much like megapixels in digital cameras and take-your-pick specification metric in amplifiers, is a poor judge of quality and often used for marketing purposes. Luckily, the engineers at 64Audio have been able to pack in a whopping number of drivers without losing focus on creating a clear, coherent sound that is both faithful to the source and enjoyable to listen to.

While our shared hobby and the primary focus of most discussions is sound reproduction through speakers, I really felt that I needed to share this marvelous piece of engineering with the broader forum. If my words betray a positive impression, then you would be correct, but hopefully there is still an inclination to read further.

Conclusion/Why Is This Special

I started out in this hobby with headphones and my earliest audio grail was a pair of CIEMs. I bought some a few years back and I couldn’t have been happier about biting the bullet. Recently, I wanted to pick up a new pair to see what the latest and greatest in CIEM technology can do. I have been firmly a 2.0 stereo listener for the past 8+ years, having sold off all my headphone gear and only using the CIEMs for travel. The A18T has become a cherished piece of audio gear that I look forward to listening to rather than something I feel I have been banished to because I can’t blast my speakers at all hours of the day.

Listening to the A18T, I find myself thinking about the fractal nature of all things. In this case, I notice how some of the acoustic design elements reflect design choices made by designers of some top notch speakers. Perhaps these design principles scale down into IEMS much the same way they scale up into the flagship speakers. Stepping away from my left brain tendencies, I notice that the delivery of music is as dynamically rich and textured through the mids and highs as any quality speaker set up I’ve heard. I notice that music flows effortlessly in the way I’ve heard from countless stats: extended, layered, holographic. It’s this layering that allows the A18T to transcend the confines of headphone audio and create a detailed image from the music. It’s not a speaker...but it doesn’t sound like a headphone either…

I’ve had these for well longer than what I would consider a honey-moon period. I love listening to them and they have been serving me well during quarantine. The best compliment I can give is that when I listen to them, I am reminded of what I love about my own speaker system and it shows me a different perspective on the music that encourages me to push my speaker system further.

I think any audiophile, even one that prefers speakers, seeking a world class music experience on the go should look into these.

Part 2

Process, Fit and Finish

CIEMs are a bit of a process to get done. You have to have your ears molded by and audiologist, send in the mold to the company where they will 3d scan it, and then wait for the unit to be built to the exact shape of your ear canal. On the surface, this seems like a bit of a hectic process but it really isn’t. It took me all of 20 minutes to get my impressions done and another 10 minutes of foibling around a local FedEx to ship them to 64Audio in Washington state. They were there in 3 days and the construction of my in-ears began.

For my fellow New Yorkers, Dr. Servideo on 200 W57th St. is a great place to go for impressions. He works with many artists and is an audiophile himself. It makes the process much easier as he packs everything to ensure that the molds remain safe in transport. Impressions run anywhere from $60-$90, so remember to factor that into the cost of the product.

I chose to have my A18’s done with a beautiful rose gold plate (+$250...YOLO!) and clear smoke shell color. The shells are 3D printed in acrylic. I had hesitations about acrylic based CIEMs as I was previously using silicone based ones (which heat up and soften as you wear them), all concerns flew out the window as soon as I put them in. They are easily much more comfortable than my silicone based CIEMs and I can comfortably wear them 6+ hours without needing to take them out to let my ears breathe.

64Audio has embraced 3D printing in their manufacturing process. Not only are the shells printed but even the carrying case they come in 3D printed. It’s really cool, and makes you marvel at a potential future when more and more items can be 3D printed...beyond the sound, I’m really taken aback by how far 3D printing technology has come from early days when I had a few friends who were hobbyists and tinkering with it.

Technology

As mentioned earlier the A18T is the 18 driver flagship CIEM for 64Audio. These balanced armature drivers include a TIA high end driver. TIA stands for Tubeless In-ear Audio. I highly recommend reading about it on the site as I see some design practices that look familiar in high end speakers. The open balanced armature driver is able to breathe and it sits in an acoustic chamber to shape and direct the sound out of a single bore thus creating a short pathway for the high frequencies that are free from unwanted tube resonance. At a high level, this is reminiscent of two interesting designs that have been influential in the speaker world. The first is the idea of a wave guided tweeter as used by Rockport, Goebel, and many others and the second is the mid range chamber that Magico uses in their Smk2 and M series. By my recollection, this was first introduced in the M Project and was one of 4 major changes in the Smk2 over the Smk1 (the other three being the larger/heavier chassis top plate, diamond coating on the tweeter, and outriggers for the feet). I will touch on what I think this technology brings to the table in my sound impressions section below.

The other interesting technology is the use of modules and venting for the bass. Apex modules come in two flavors: -15db isolation (m15) and -20db isolation (m20). The models can be swapped in and out of the iem with ease and each CIEM is shipped with both. The vents allow the air pressure built up in the ear canal to dissipate, which, 64Audio claims is better for ear health and for avoiding listening fatigue. I don’t have the requisite testing to verify this but on a pure sound quality perspective the modules make significant changes to the sound signature. I would go so far as to say you are getting two flagship CIEMs for the price of one. For a simple comparison, consider the differences between open back and properly implemented closed back headphones. Another similar feel is that of moving a ported speaker closer to or farther away from the wall behind it.

Sound Impressions

My musical tastes are varied but lean towards more modern music. Rap, hip hop, electronic, atmospheric/dream pop are my usual staples.

m20 Module

I used the m20 for the first few weeks I had the CIEMs and have done my listening with the m15 since. The m20 is not bad by any means, just less in line with my tastes. There is a wonderful fullness through the mids and the highs are extended but, to my ears, the sound is not as dynamic and alive. There is body to the sound but the layering is not as apparent because elements deeper in the mix are opaque. The bass really digs deep with power. There is a consistent delivery of force through the mid bass and into the sub bass. The soundstage height is minimal but width and depth are good

I can see many people preferring this and really loving the sound because of the heft while being transparent but my own tastes lean to the m15:

m15 Module

The m15 is tonally gorgeous. The timbre and texture is really as good as any high end speaker I’ve heard. While it is not full through the mids in the way the m20 is the mids are more dynamic. The highs extend cleanly and create a sense of air and space between the notes. The bass is politer, less dynamic, but clean. Think sealed speaker bass. The politeness on the bass allows details to flow out of the mids with ease. This adds to the sense of space and creates the most spacious sound I’ve heard in an ear and rivals the hd800. The height of the stage is still limited. But, to my ears, I can’t shake my attention from the tonal accuracy. This is a monitor after all and every drawl and inflection in a voice - male or female - is easily apparent and delivered with dynamic force. Because of the agility of the bass, I found this module to have a sound that is faster. I’ve noticed over the years that I am particularly sensitive to speed in sound and prefer a faster speaker to a slower, more relaxed one.

For hip hop, the dynamic contrast with the speed allows a beat to flow while vocals are free to hit consonants at different time steps within the beat. If you like digging into a record, picking out samples, listening for interpolations on beats and bars, and enjoy the subtle shifts in breath and timing that change the atmosphere of a song, this is your monitor.

Sources

I was able to listen to these through (in order of hours used) my macbook pro, pixel 4xl with usb c to headphone port, hugo2 + 2go as roon endpoint, and hugo2 micro usb out to usb via usb c adapter. Big thanks to my friend Tom at THX Stereo for loaning me a hugo2 and hugo2go in order to test these on a portable source.

Hugo2: I really detest micro usb. Horrible drivers for mac. Sound is pretty good but not worth the bs.

Hugo2+2go: This was really cool. Having a portable roon endpoint that I could move around the house was really convenient and battery life was pretty solid. With this, the soundstage opened up considerably vs. laptop and the bass - well, what would you expect from 8 low drivers per ear...these growl. The bass is tighter and more dynamic. Unfortunately, the chord felt a bit too sharp on the highs and not as much body through the mids. It was enjoyable and I certainly think the amp brought out the best of the bass and imaging but I feel there may be better synergies with other amps+dacs.

Phone: Not bad. I used it to walk around. Volume got loud enough to drown out most ambient city noise. I wasn’t doing critical listening but while running errands I easily found myself getting lost in the music.

Macbook Pro: Honestly, awesome. They run great and for anyone on the fence, I’d say don’t hold back if you don’t have a great headamp or something. It’s something to add down the line but certainly won’t keep you from enjoying these. The quality of sound vs. simplicity of set up is really high. I’m able to easily determine sound differences in tidal through roon and tidal itself. Songs have spacious staging but slightly smaller than the Hugo. The largest drawback of the sound is that the bass is not nearly as dynamic. The Great for use during work sessions because of the comfort and the ability to flip between tunes, zoom calls, and youtube videos without dealing with additional hardware.