I’d like us to think about the Bel Canto Black ACI 600 in architectural terms.
By architectural, I mean like a building’s bones where each part is an essential piece of the whole and removing this bit or that results in the structure’s collapse. The end of its function. Similarly, you can’t just remove the DAC from the ACI 600 because it is, very much like a keystone, an integral part of the overall design.
Some words from Bel Canto on ACI 600 tech:
Bel Canto’s High Dynamic Resolution-II (HDR-II) core is a highly refined Digital to Analog Core rendering high levels of definition and musicality. It is the culmination of more than 20 years of audio DAC design evolution. With the HDR-II Core we have improved the dynamic range, analog output stage design and digital filters while reducing spurious signal generation and jitter related errors. Our new HDR-II Core has demonstrated that we can increase the resolution of musical detail, and improve listenability and perceived quality of the recorded music. This is in contrast where ‘transparent’ and ‘revealing’ often means ‘bright’. The HDR-II Core presents the original music with high levels of clarity and emotion.
This core is fed from the ACI 600’s inputs which include Ethernet (Roon Ready & UPnP/DLNA compatible), USB, “legacy digital” SPDIF/AES/TOS inputs, a pair of analog line level RCAs and a MM/MC phono input. Full Function.
You may have noticed I left in Bel Canto’s comments regarding sound quality which I typically omit when quoting tech stuff but in this case their words mimic my thoughts as the ACI 600 is stunningly transparent while also being a music-making machine of the first order, by which I mean it makes recorded music sound and feel endowed with all its original bits including emotion, tone, texture, and force in tact. A kind of uncanny combination of matter of factness and drama.
Here’s Bel Canto again:
A critical advantage of our HDR-II Core architecture is how the Class A Differential Current Mode output from our DAC operates in concert with our custom balanced analog section to best preserve the original dynamics of the recording. The large constant-bias differential currents impose pure Class A operation to every part of the analog output stages, every precision resistor, film capacitor and amplification device is biased with constant current and voltage. This constant bias keeps all components in thermal stasis and insures that all the original signal dynamics are retained.
Bel Canto refers to this bit of architecture as their “proprietary SSHA (Single Stage High-Current Amplifier)”:
Our proprietary SSHA (Single Stage High-Current Amplifier) interposer module is used in the Black HDR-II and Black EX DAC Core design. This is a very fast, low noise amplifier with a single-stage folded cascode architecture and over 500mA of peak current output capability. It maintains constant very low distortion levels through the audio band because of its high open-loop bandwidth. The SSHA module brings a further element of dynamic resolution and contrast to the HDR-II Core. The vertical modular design permits a tight, efficient Printed Circuit Board (PCB) layout that combines the best of IC based and discrete component design. The PCB represents a final degree of design refinement that is especially critical when the circuit is capable of 130dB of dynamic range or more.
I would have loved to provide an elevator pitch explaining the ACI 600’s ins and outs but I hope I’ve hinted at what we’re looking at is a rather unique package. While we’re here, reducing complexity into sound bites, the ACI 600 is less than 4″ tall, weighs 45 lbs., and puts out 300 Watts of power into 8 Ohms / 600W into 4 which should tell you all you need to know about Class. I’m not going to say another word on this as some people think that all brick buildings look the same, to stick with our architecture analogy. In my experience, what matters more than amplifier types and DAC filters is the result, which when it comes to an audio device boils down to how it makes music sound and of greater importance how that sound translates into what we experience.
Some people, and I’m not joking, think that thinking about things like amplifier types and DAC details are more important than listening. No wonder they always seem unhappy.
But that’s not the end of the story as the ACI 600 has some other tricks up its processor, namely a 64bit DSP engine and its associated Tilt, Bass EQ, and High Pass filter functions which are accessed via the top mounted control wheel or the included remote. Bass EQ “operates over a +/-3dB range with 0.6dB increments (–5, Off, +5) providing subtle optimization of bass energy”and the High Pass filter is used to help properly blend a subwoofer with your main speakers.
In use, I found the Tilt function useful when the ACI 600 drove the YG Sonja 3.3 as a loudness control (to age myself) in that a very slight tilt bringing up bass response and lowering HFs came in handy when listening at lower than normal volume levels.
The Bel Canto Black ACI 600 got to play with 3 pair of speakers including the recently reviewed MC Audiotech TL-12, YG Sonja 3.3, and Barn resident DeVore Fidelity O/96. A kinda wildly different bunch yet each worked with the ACI 600 in their own way. I almost always used Roon to control playback, both music choices and volume control, because it’s the way I roll and I have yet to find another app that makes playing files feel like something more than playing files. Of course you can also use your UPnP/DLNA app of choice or Bel Canto’s free SEEK app for iOS that supports Tidal, Qobuz, Spotify, and vTuner.
All cables used were from AudioQuest and since the ACI 600 got to experience both sides of the Barn, A and B, these included Diamond and CAT700 Carbon Ethernet cables, FireBird and ThunderBird interconnects, ThunderBird Zero and Robin Hood speaker cables, and Thunder and Blizzard power cables, with power handled by the Niagara 3000 and PowerQuest PQ707 (see full Barn and system details).
The Black ACI 600 sat on racks from Box Furniture and to my eyes its black aluminum sleekness and minimal design, in form and function with that single control wheel up top for volume and input selection and red LED display, added to its uncanniness as its modest proportions belied its multi-functions and effortless power coupled with that combination of matter of factness and drama which was on clear display whenever music was in play. While there’s an included remote, I made due with Roon and that control wheel for its tactile pleasure.
Spine from Kee Avil is a bass heavy excursion into self.
From the liner notes:
Kee’s voice hisses, whispers, and chants; her guitar bends and rings; electronics skitter and crackle; violin creaks like a door in the wind. There is something so evocative about the atmospheres she creates that it’s easy to overlay one’s own feelings onto her work, but to do that wholly would be to overlook one of the most important things about Spine: Kee Avil’s clear and thoughtful vision.
Overlaying one’s own feelings obscuring the thing at hand, or in ear in this case, is a common theme in experiencing. In general. I only hit on this wonderful sophomore release from Avil recently, when the ACI 600 was connected to the DeVore O/96 and in a matter of a few bass throbs in, I was reminded of two things: a) the DeVores do bass, and b) the Bel Canto also does bass, big. Spine, as you might imagine, is rather skeletal sounding, raw, and intense and all of these entrancing qualities filled the Barn and me with pure sound-generated emotion, the kind of physical and mental combo meal that makes listening to music on the hifi so vital, so damn addictive. When reproduction reaches this level of pure transparent power, transporting us to the beating heart of music seemingly without obstruction, all thoughts of topologies, types, classes, and Watts fly out the window—and I always leave one open.
I’ll let you in on a little secret—when I talk about and listen to Jimi Hendrix in a review, you know I’m very happy. I’ve mentioned this before but Jimi, we’ve known each other for more than 40 years, was my first musical love and I find most of the posthumous releases kinda sad, like finding an old photo of a lost love in a junk drawer. But one clear exception is Machine Gun: The Fillmore East First Show, released on Legacy in 2016 (unfortunately Tidal does have this album), a live set from the day before Band of Gypsys. This was a glimpse of Hendrix’s new direction with Buddy Miles on drums and vocals and Billy Cox on bass, replacing The Experience for a deeper dive into soul. But the title track, “Machine Gun” recorded on December 31, 1969 is a perfect slice of Hendrix magic, sounding like much more than a guy with a guitar (and effects).
I let this track rip on the DeVores and through the big Sonja 3.3, yes I was having that much fun, and I enjoyed both presentations. Thoroughly. You may be thinking that pairing a $30k Class-D based integrated amp with the 96dB dB/W/M O/96 is kinda weird but I’m here to tell you they made magic. It has been my experience, over the course of many years and dozens of amplifiers, that the DeVore O/96 can tell you a lot about an amplifier’s soul. By that I mean the O/96 allows the voice of the amp to shine through and they have kept pace with amps of all kinds, some costing many times their price. A neat trick. For a simple one box solution, the ACI 600 had the DeVore’s singing out in full blossom with superb bass control while throwing out an enormous and rich sound image fit for the deepest of deep exploration.
Another fun fact about the ACI 600 is it also drove the big Sonja 3.3 to Barn-rattling extremes, while also doing delicate and nuance like a pointe shoed dancer. Weavings from 2022 is a feather, breath, and bleep of an album.
From the liner notes:
Conceived by Nicolás Jaar, “Weavings” is a durational improvisation structured in the manner of a long fabric of sound. Artists include Aho Ssan, Ka Baird, Angel Bat Dawid, Ellen Fullman, Dirar Kalash, Księżyc, Laraaji, Jaar himself, Resina, Paweł Szamburski, Juliana Huxtable, Rolando Hernández Guzmán, and Wukir Suryadi and Rully Shabara of Senyawa.
The work was recorded in one sitting without a break on 30th November, for the Unsound 2020 online edition, with performers joining from around the world using Zoom and a high resolution audio plug-in. Jaar had less than 24 hours to mix the work into a whole, then streamed it live from his own computer as the first performance of the festival.
You remember that notion of judging a hifi by its ability to recreate a live, acoustic event? Well, this album is a great choice for sussing out a hifi’s ability to render nuance, subtlety, micro movements, timbre and more even though there was never a there, there to reproduce. Just sayin’. The ACI 600 dug deep into Weavings and with the O/96 in the picture the Barn’s B-Side was filled with its rich tapestry of delights. There’s something to a clear sense of rightness, a kind of synergy plus that happens with some amp/speaker combinations and the sounds of voice, acoustic and electronic instrumentation stretched out in drone time transforming the Barn into a giant pulsing music box. Nice.
I know you know I’m not a headphone listener but for completeness’ sake, I leashed the trusty and lovely Meze Audio 109 PRO ‘phones to the ACI 600 and let them play with Quade’s latest, The Foel Tower, which is a masterful mix of sparse and smash and as you might expect, the ACI 600’s delicacy, control, and delight shone through loud and clear. “a beautiful mysterious story in song and sound” is what I wrote about The Foel Tower and this played out just as well during my more personal headspace listening time.
I’ve reviewed a number of Bel Canto products including the e.One Pre5 Preamplifier and REF501S Stereo Amplifier combo, e.One C6i DAC Integrated Amplifier and e.One Stream2 Network Bridge combo, and the E1X Integrated Amplifier over the course of the past 4 or so years and while it may seem like something that doesn’t need saying, the Black ACI 600 is my favorite by a wide margin as it seems to insert more of music’s human magic into every note.
In terms of comparisons, the two integrated amplifiers that sit on my list of Favorites that are in the same price ballpark include the Viva Solista, an 845-based beautiful beast of an amp, and the more recently reviewed and much-loved Soulution 331. If you think there’s a winner, and therefore losers, among this trio we live on different planets because each has their own voice, set of sonic strengths, and features that will perfectly mate with your preferences and speakers. Or not. That said, if you lean towards a love of bold technicolor riches, seek out the Viva. If you’re looking for clean, clear, transparent power that lets music shine through, the ACI 600 may be your perfect mate. If you want something kinda in between, think Soulution. Of course listening beats words any day of the week.
I took the ACI 600’s MC phono stage for a long run using the Barn resident Michell Gyro SE Turntable/Sorane SA1.2 Tonearm combo with the EMT HSD 006 cartridge and after dialing in the appropriate gain and load settings, I was greeted with vinyl’s forte—sumptuous loveliness. I unboxed, on video for Patrons, a big stack-O-LPs including Antony and the Johnsons Crying Light, FKA Twigs latest Eusexua, Bonnie “Prince” Billie’s 10” Hummingbird, and Psychic 9-5 Club from HTRK to name just a few and I let ‘em rip ‘round the Michell/Bel Canto/Sonja 3.3. system and here’s the thing—I could easily live with the Bel Canto as everything, streaming integrated amp and phono pre. All in one, simple and done.
To my mind, while you can do better by spending more on a separate phono stage, that kind of thinking has no end. The sound is always greener…The real trick is to take your time listening and recognize delight when you hear it and I was delighted by this simple system, digitally and analog-ally.
The Bel Canto Black ACI 600 is obviously a masterfully executed music-making machine that transcends topology and type, and is more than capable of handling all of your digital and analog needs with more than enough juice to drive most sensibly designed speakers into pure delight. Its main sonic signature is a combination of transparency and richness that results in a beguiling mix of matter of factness and drama, delivered in a sleek minimal package that transforms listening time into timeless music-filled magic.
Bel Canto Black ACI 600
Price: $29,999
Company Website: Bel Canto
Specifications
Maximum Data Input Rates:
24bit Data to 192ks/s: AES, SPDIF, TOSLINK
24bit Data to 192ks/s, MQA, and DSD 64: 10/100 Ethernet
24bits at 192KS/s, MQA, and DSD64/128 (DoP): USB2 Audio
Low Level Outputs:
Line Level Analog: 4.5Vrms with Bass Management
ST Fiber Digital Outputs: 2- MPS1 Compatible
Headphone: 4.5Vrms maximum, 32ohm minimum load
MM/MC Input:
Input Sensitivity: MM: 2.5mV to SmV; MC: 0.25mV to 0.5mV
Input Load: MM: 47K ohms; MC: 50, 100, 500, 1000
RIAA Accuracy: +/- 0.25dB, 50Hz -— 15kHz
THD+N: <0.01% 1kHz A-weighted
SNR: >70dB A-weighted
Line Inputs:
Maximum Input: 2.2 Vrms RCA
Input Impedance: 10K ohms RCA
THD+N: 0.003%, 1kHz
Dynamic Range: 110dB, A-weighted 20Hz-20kHz
Loudspeaker Output:
Maximum Power Output: 600W – 4 ohm, 300W – 8 ohm
Minimum Load: 2 ohms
Peak Output Current: 27 amperes
Frequency Response: -3 dB OHz — 50kHz, all loads
Output Connections: 2 pair WBT Nextgen binding posts
Performance:
Dynamic Range: 127dB A-weighted
THD+N: <0.001% 1W, 1kHz, 4 ohms
IMD (CCIF): <0.001% 1W, 18.5:19.5kHz 1:1, 4 ohms
General:
Power Usage On: 42W
Power Usage Off: OW
Power Requirement: 100-120VAC or 230-240VAC 50/60Hz Internally Set
Dimensions: 19W x 14D x 3.8H inches — 483 x 356 x 97mm
Weight: 45lbs (20.5 kg)