As they have done with their loudspeakers over the last few years, Focal has put together an enviable, well-thought-out collection of home listening headphones. I got to sample each of the five models at CanJam NYC earlier this year and the Stellias immediately got my attention, along with the new Focal Arche DAC/Headphone Amp that they were hooked up to. After some inquiry, Focal was nice enough to send the pair to me for an extended review.
Focal Stellia Headphone and Arche Amp/DAC
- The Stellia headphones have a very balanced, natural, and intimate sound quality.
- They are easy to drive whether by amp or by a portable device.
- Beryllium diaphragms in the drivers.
- Very comfortable fit.
- Aesthetically, they tick all the boxes for me.
- Has an integrated headphone stand.
- Dual-mono Class A amplifier architecture can drive difficult headphones.
- Will work as a preamp if needed.
- Has special drive modes for each Focal Hi-Fi headphone.
Since 2016, Focal has methodically gone about and built an impressive line of home headphones that have garnered accolades from all over audio-dom. Beginning with the statement Utopia and the more accessible Elear headphones, both open-back designs laid the groundwork for the addition of the mid-line open-back Clear headphones and then Focal’s first closed-back entry, the Elegia as an introduction point. The Stellia that I have in for review was introduced in 2019 and is a higher-end closed-back model that slots just under the Utopia in the overall headphone pecking order.
The Focal Arche DAC/Headphone amplifier was introduced earlier this year and it has several interesting features including a dual-mono Class A amplifier architecture, dual DAC chips, and custom drive/impedance modes for each of Focal’s headphones. And, in an interesting twist, the Arche has a built-in headphone stand which, after you use it for the first time, seems like a stroke of genius.
Purchased separately, the Focal Stellia headphones cost $3000.00 and the Arche has an MSRP of $2500.00.
But Focal-Naim America, the North American distributor, allows any of the Focal home audio headphones to be purchased in a bundle with the Arche at notable savings. In this case, a Stellia/Arche bundle would cost $4000.00. And not to leave existing owners out in the cold, if one already owns a pair of Focal Clear, Stellia or Utopia headphones, Focal will offer you a $1000.00 voucher towards the purchase of an Arche through to the end of 2020. Not a bad deal if you are shopping in this price range. So are the Focal Stellia and Arche a winning combination to auditory bliss? As Stan Lee once said, “Read on True Believers” and let’s find out!
Focal Stellia Headphone
Circumaural, Closed-back Headphones with Dynamic drivers
40mm Dynamic Driver with Pure Beryllium Diaphragm
Manufacturer Freq. Response:
5 Hz – 40 kHz
106 dB SPL / 1mW @ 1kHz
0.96 lbs (435 grams)
Cognac and Mocha finish
1 x 4ft OFC 24 AWG cable with 1/8″ (3.5mm) TRS Jack connector
1 x 10ft OFC 24 AWG cable with 4-pin XLR connector
1 x ¼ inch phono plug adapter
Hard shell carrying case
Focal Arche DAC/Amp
Desktop Headphone Amplifier with Integrated DAC
2 x 1W @ 1kHz under 32 Ω
Dual AKM AK4490 DAC chips each run in mono mode
Manufacturer Freq. Response:
10 Hz – 100 kHz
Total Harmonic Distortion (THD)
Signal to Noise Ratio (SNR):
> 116dB @ 32 Ω (Class A)
Audio Inputs: Unbalanced analog RCA
Digital S/PDIF coaxial (RCA): Up to 24-bit/192 kHz PCM
Optical digital (TosLink): Up to 24-bit/192 kHz PCM
Digital USB (USB-B): Up to 32-bit/384 kHz PCM and DSD256
Unbalanced analog RCA
Balanced analog XLR
10.25 lbs (4.65kg)
60 x 200 x 297mm (H x W x D) without stand
1 x Headphone Stand with Mounting Hardware
1 x AC Power Cord
focal, stellia, arche, headphone, amp, dac, closed-back
Before getting into the design of the Stellia headphones themselves, I want to take a moment to touch on the packaging and presentation of these headphones when first unpacking them. At their suggested price point the Stellias qualify as a luxury item and I think the packaging properly reflects that category. A warm brown leather-bound outer box lifts open to reveal a brown tweed-like hardshell case containing the headphones and a smaller leather-bound box that contains the cable sets and accessories. Within that box is a leather billfold that holds the user manual, warranty information, and other documentation. All the brown leather and attention to detail made me feel like I was handling a high-end product from the likes of Coach or Louis-Vuitton. It makes for an extravagant first impression.
Unlike the cooler grey, silver, and black colors that Focal uses in their other home Hi-Fi headphones, the French maker decided to go with more earthy tones here. Burnt Siena and Copper (they call it Mocha and Cognac) are the colors that dominate Stellia’s visage which is, aesthetically, very much to my liking. In fact, the whole look of the Stellias, with their abundant use of stitched and perforated full-grain leather on the headband and earpads, the copper-colored metal arms and ear cups, the design elements on the outside of the cups and polished metal trim all make for a very Steampunk kind of statement.
Again, me likey! Close examination of the surfaces and the mechanical actions show that everything is finished and functions to a very high standard. They feel expensive. Even the included single-ended and balanced cable sets look the part with brown tweed jacketing and high-quality connectors. There is a fine balance between “high-tech” and “old-world” feel happening with the Stellias and, as such, they are some of the most aesthetically pleasing headphones that I have yet come across.
Each earcup holds a 40 mm dynamic driver with a Beryllium diaphragm that attaches to the driver frame with a half roll surround. This makes it look even more like a speaker driver than what you’d typically find in a headphone. The surround is said to help improve bass response and dampen any high-frequency distortions. Beryllium, seemingly the material of the moment, was chosen for its lightness and stiffness in this application and it no doubt helps in giving the Stellias their high sensitivity rating of 106 dB/1 mW. This combined with the claimed 35 Ohm impedance should make these headphones none-too-difficult to drive with most portable devices. The interior of the earcups themselves also features a significant amount of acoustical tuning through the use of absorption and diffusion materials and precision-tuned venting.
With the weight at just shy of a pound, I did not find the Stellias to be overly heavy while I had them on but, at the first try, I was concerned that the clamping force might be just a little more than I would have liked. After about a weeks’ worth of use, the Stellia’s grip lightened up enough that it no longer troubled me in the least. The leather earpads on these Focals are extremely comfortable and the openings completely encircled my large-ish ears creating an excellent seal. Being closed back headphones they did a good job of naturally blocking out a good deal of external noise.
In terms of accessories, the Stellia’s arrive with two robust braided cable sets. One is a balanced cable that is terminated with a Neutrik 4-pin XLR plug while the other is a single-ended cable that finishes with a 3.5 mm connector. A ¼ -inch screw-on phono plug adaptor is also provided. Both cables use two single-pole 3.5 mm plugs to connect to the earcups themselves. A matching hard-shell travel case completes the package.
The Focal Arche is a fairly compact headphone DAC/Amplifier combination that Focal produces in conjunction with the French audio company Micromega. The first thing that stands out “literally” about the Arche is an integrated aluminum headphone stand/arm that juts out of the top of the case. It’s a clever little touch of design genius that I haven’t encountered before on a similar kind of product. The front face of the Arche features a central rectangular, monotone display screen flanked by a 4-pin XLR and single-ended headphone jacks on the left and power LED and push/rotary dial on the right. The display itself is very easy to read and on-screen navigation is simple and intuitive via the rotary/push knob.
Turning to the backside we have three digital inputs (Asynchronous USB, TOSLINK, and SPDIF Coax) and a set of analog RCA inputs. Outputs consist of a pair of balanced XLR jacks and a pair of single-ended RCA jacks. There is also a power switch and another USB port that is exclusively for service updates.
Delving into the guts of the thing, the Focal Arche is billed as a completely dual-mono design. It incorporates a pair of AKM AK4490 DAC chips, one per channel, and then two channels of Class A amplification claimed to be capable enough to effectively drive 600-Ohm headphones. The Arche can be used as a standalone DAC or a preamp via its various inputs and outputs. The volume and amplifier gain settings affect both headphones and standard outputs. In High Gain mode, the Arche puts out well over 2 Volts at the RCA and 4 Volts at the XLR jacks. It will have no trouble driving external amplifiers when used as a preamp in a home stereo situation.
Beyond the expected features a product at this level would have, including high order native DSD (DSD256) and PCM (up to 24-bit/384kHz) playback via USB (Windows driver can be downloaded from Focal’s website), the Arche offers a choice of preprogrammed headphone amplifier output/impedance settings depending on what headphones you are using. Accessible via the front display, the choices are Voltage (standard), Hybrid (a combination of voltage and current), and then custom selections for each of Focal’s Hi-Fi headphones, including one for the Stellia.
The only additional accessories included with the Focal Arche are a power cord, an Allen wrench to assemble the integrated stand, and 4 rubber disks to place under the fixed shallow metal spike feet on the base of the enclosure.
When on the go, I paired the Focal Stellia headphones with either my iPhone 6S Plus using the Onkyo HD Player app or a Shanling M0 DAP mated to a Topping NX4 DSD portable DAC/AMP. For home use, the headphones were connected to the Arche which was tied to my Surface 3 Pro tablet via USB. The Surface uses ROON to access all my digital music files via external hard drive and the Qobuz streaming service.
On their own, the Focal Stellia is a very transparent, balanced, and natural-sounding pair of headphones. To my ears, they did an excellent job covering all the bases with a wide range of music that I sampled with them. As a general pattern, most headphones that I’ve listened to tend to play better with some recordings or even whole genres of music than others. My portable players are filled with a wide variety of favorite tracks and are perpetually set to shuffle them. So I’ll be listening casually, enjoying, for example, a favorite jazz track and then a classical piece will come on and I’ll cringe just a bit because the treble may be exaggerated or a rock track will come on that sounds flat because there isn’t enough bass or the treble is too rolled off, etc. Very few headphones will sound agreeable with everything that I toss at them. The Stellias are one of the few headphones I’ve encountered that genuinely do. Being a closed-back pair of headphones, the sound was definitely closer and more intimate, as you would expect, but at the same time, the focal point of the music wasn’t jammed inside my head which I appreciated. The overall imaging was pleasantly broad but not as expansive as the Astell & Kern AK T5P 2nd Gen which I reviewed a little while ago. Bass response was that “Goldilocks just-right” amount which gave perfect definition and weight to basslines, drums, and lower register piano but also plenty of impact for electronic music, ala Tron Legacy, without the rattling of my skull. The Stellias kept vocals immediate and clear sounding with just the right amount of warmth. Treble was nicely judged as well without the artificial sense of detail that sometimes comes from the overly boosted highs in some headphones. Referring back to the Astell & Kerns for comparison, the bass in the Focals was less fun but more authentic and the treble was a little more extended and clean. In a real sense, they sounded more like a very good pair of speakers in a sympathetic room.
My HiFiMAN HE1000v2 is my standard reference headphones and are in the same price class as the Stellia. It may be a bit of an apples-to-oranges comparison since they are completely different designs, but I think there are a few constructive takeaways to be had. Putting aside the spaciousness differences between the sound of open and closed-back headphones, the Focals seemingly had a more balanced tonality than the HE1000v2. The HiFiMAN cans had just a touch lower bass punch with the upper midrange and treble being significantly more prominent in back-to-back listening. It made them sound a little leaner by comparison. I like both these headphones very much and the HE1000v2 are magnificent to listen to with most things when I’m sitting at my desk, working late into the night. But I do grant the Stellias a little bit of an edge for being a bit more balanced and flexible with a wider variety of music and I could use them on the go if I really wanted to. I don’t dare take the HE1000v2 outside. Also, the Stellia outclass the HiFiMAN when it comes down to fit and finish and materials choices.
When mobile, the Focal Stellias were easily able to be driven to more than sufficient levels with either my iPhone or my little Shanling DAP on their own. Adding my Topping DX4 Amp/DAC into the mix wasn’t necessary from a loudness perspective but the Stellias did benefit from slightly better resolution and detail due to the better-quality DAC chipset and lower distortion amplifier. I will admit to feeling slightly self-conscious wearing the eye-catching Focals first thing in the mornings while walking my dogs. Sweatpants and Stellias may not exactly go together as a fashion statement but none of the other neighborhood joggers or walkers seemed to regard me as a Kardashian-in-training, so I stopped worrying about it and just enjoyed my music!
Still, I expect most people who plan on dropping the kind of coin required to purchase the Focal Stellias will keep them predominantly indoors. To that end, the Focal Arche DAC/amp seems to be an ideal companion to drive said headphones in question. Hooked up to my Surface tablet with the proper Windows 10 drivers installed, the modestly sized black box did indeed successfully natively decode every conceivable PCM, and DSD bitrate that ROON could throw its way. I encountered no skips or USB playback issues of any kind with the Arche, its performance was always consistent and reliable. The Stellias were quite happy operating with low amplifier gain when paired with the Arche. There was always plenty of headroom to spare. The Arche had no problem powering my HiFiMAN HE1000v2 in high gain mode with the volume about a third of the way up. My harder to drive 250-Ohm Beyerdynamic DT-800 PROs also sang very nicely with the Arche in high gain with the volume dial halfway up.
Experimenting with the custom drive/impedance settings on the Arche was interesting in a number of ways. Switching between Voltage and Hybrid modes on the Arche with a variety of different headphones, it was difficult to hear much of a difference between the two modes. At times, I thought that Hybrid mode helped give my DT 800 PROs a little more oomph in the bottom end, but I can’t be entirely certain it was real. When using the Stellias and switching between Voltage or Hybrid and Stellia’s custom setting, I heard a very noticeable difference in sound. The Stellia drive setting resulted in a modestly lowered volume level and a softening of the treble when compared to either Voltage or Hybrid. The resulting sound is what I would associate with using a tube amp with the Stellias, slightly softer and rounder to my ears. In the end, I found myself keeping the Arche mostly in the Voltage setting as it seemed to sound more satisfying and correct to me. The Arche also allows you to invert the phase on a recording, which I played with a few times but found no noticeable change with the material that I tried.
The Arche can be used as a standalone DAC and/or preamp if you choose. I did try it as just DAC by connecting it to both a pair of STAX headphone amps that are in for review and to the Benchmark HPA4 preamp/headphone amp also in for review. When used in this manner, the instruction manual recommends opening up the volume control on the Arche to full (99 on the display).
Subjectively speaking, in Voltage mode, I think the Arche sounded clear and uniformly outstanding with whatever headphone that I paired with it. It certainly doesn’t lack for power and while I don’t have any 600-Ohm headphones around to try out, I think that Focal’s claims of the Arche being able to amply power such units is quite credible. When I compared it directly, and level-matched, with the Benchmark HPA4/DAC3B combination (listening through the Stellias), the Arche was a little softer sounding in the upper-mids and treble. The Benchmark stack had a little more natural clarity up there, almost as if there was a little more music at that level waiting to be heard. That being said, the Benchmark stack is almost twice the price of the Arche when purchased standalone. It’s certainly evident that the Arche is a well thought out and flexible listening component with many nice touches that one might not otherwise find in a comparable desktop DAC/Amp. When purchased (at a discount) as part of Focal’s headphone/Arche package deal, it becomes a rather compelling choice.
The New Stan Getz Quartet, Getz Au Go Go, Verve, 1964, 24/192 FLAC from HDtracks
As I mentioned earlier, I found that the Stellia’s sound profile played nice with a wide variety of music that I had on my playlist. “The Telephone Song” from The New Stan Getz Quartet’s live set “Getz Au Go Go” had a nice wide image that had a great sense of envelopment. Some headphones can exaggerate the mid to upper bass region, making the acoustic bass in this live recording sound overly thick and muddy.
The Stellias kept things clear and clean sounding with the right amount of low-end punch when called for. Stan Getz’s tenor sax was smoothly and spaciously rendered on the left side with great detail while the repeating cymbal on the right side had that characteristic short, crisp metallic sheen come through nicely. Astrud Gilberto’s charming vocals were not overly forward and placed just in front of my face. Tonality seemed just right too.
Raya Yarbrough, Raya Yarbrough, Telarc Records, 2007, 16/44 FLAC
Listening to a more modern female vocal recording like “Dreamer’s Ball” by Raya Yarbrough, the Stellia’s did a superb job getting every breath, vocal inflection, and subtle detail to Ms. Yarbrough’s performance and they played it back with the utmost clarity. Her vocals can sound overly thin, especially towards the song’s climax, with some other headphones that have an upper-end bias, but not so here.
The supporting background singers that perform acapella have a diverse array of pitches and fill in the soundstage nicely, again each one rendered clearly. The accompanying acoustic guitar has some great sounding detail to the strings and the hollow body resonance has a solid dimension through the Stellias.
Billy F. Gibbons, The Big Bad Blues, Concord Records, 2018, 16/44 FLAC
These particular Focal headphones will do delicacy and refinement all day long but, if the opportunity arises, they will get downright feral if you ask them to. Case in point, “Rollin’ and Tumblin’” from Billy Gibbons off his Big Bad Blues album. A rampage of distorted, raunchy blues guitars, thundering electric bass lines, hard-driving drums, and ragged vocals. It’s a musical runaway train of the best kind.
Stellia (can I call her that?) will just let down her hair, drop all sense of pretense and boogie hard with this kind of music. The trick with a track like this is not letting all the distorted loud stuff blur into a big loud and flat mess. Stellia says “No, no honey. Even with hard rocking blues, I will give you layers, I will give detail, I will give you depth, but most importantly…I will give you gobs of dirty, stinking fun!” I say Rock on Stellia!
Erich Kunzel and the Cincinnati Pops Orchestra, Time Warp, Telarc, 16/44 FLAC
Shifting back into the delicacy and refinement category but also a little unrestrained as well, the “Battlestar Galactica Main Title Theme,” from the classic Telarc “Time Warp” orchestral sampler, is a great bit of scoring and a great track to test the mettle of a headphone. This early digital recording still shines with great clarity, dynamics, and scale. My HE1000v2 will give the orchestra a lovely open and expansive presence but they will also tend to make the bold and brassy horns sound a little lean at points in their efforts to present all the details.
Lesser headphones can make the horn section sound altogether harsh and abrasive. The Stellias will match the HE1000v2’s bottom end punch with the bass drums, they won’t go as wide with the soundstage, obviously, yet what they do give me is plenty good. But what they especially do well with this track is they give the horn section that balanced body to their sound that I expect, and they do it without sacrificing any detail that I can tell.
Measurements by Carlo Lo Raso with Analysis by Carlo Lo Raso and David A. Rich.
As I do not have the facilities to measure headphone frequency response or headphone amplifier power output, my measurements were limited to the Focal Arche’s DAC and preamplifier capabilities. For THD and frequency response tests I used my Lynx 2B professional soundcard teamed with SpectraPLUS measurement software. For square and sine wave analysis along with SNR measurements, I used the Quantasylum QA401 analyzer and it’s associated software.
The Arche’s Low and High gain amplifier setting directly impacted the measured output from both the RCA and XLR jacks. When measured with a voltmeter the following values were observed at the outputs:
Unless otherwise indicated, all measurements were done at approximately 4 Volts using the XLR outputs.
Here we have the first of the 16-bit 44.1 kHz tests. I did them through both the SPDIF Coax and USB inputs and the results proved to be essentially identical. I am showing the Coax ones here. A 1 kHz sine wave at 0 dBFS produced a THD + N of 0.00017%.
A 16/44 10 kHz sine wave at 0 dBFS produces a THD + N of 0.00013%.
The 19 and 20 kHz test tones at -5dBFS produce clean results with no additional spurs or sidebands. In general, the Focal Arche shows excellent performance with most Redbook CD standard tests.
The Intersample Over Test was inspired by John Siau at Benchmark Media Systems. It consists of using an 11.025 kHz tone with the +3.01 dB signal peaks occurring at a phase angle of 45-degrees from the sample clock. This puts the maximum waveform peaks (higher than 0 dB) between the digital samples. According to Siau, “If audio peaks always fell exactly on a sample, there would not be an intersample overload problem. Obviously, musical peaks rarely fall exactly on a sample and most often fall somewhere between samples. This means that most recordings will have peaks that are over 0 dBFS if the highest sample values are just reaching 0 dBFS.” This condition is more prevalent in 16-bit/44 kHz CD recordings and lower bitrate, lossy formats like MP3 and can produce DSP overload problems in DACs. The above image shows how a textbook DAC should decode the Intersample Over test tone, with no additional noise or spurious tones, showing only the 11 kHz tone. A Benchmark application note goes into much greater detail with figures.
The Intersample Over Test on the Focal Arche produces a large number of spurious tones. The two largest ones at 78 dB (2 kHz) and 84 dB (22 kHz) below the fundamental, respectively. The distortions look to be non-harmonic and, in this case, the one at 2 kHz would be audible anytime an intersample peak exceeded 0dB.
Moving to the 24-bit/ 96 kHz tests, again both the USB and SPDIF Coax inputs were tested with almost identical results. I show the Coax results here. This is a 1 kHz sine wave at 0 dBFS producing a THD + N of 0.00009%. Second and third-order harmonics are both below 120 dB from the fundamental.
A 24/96 10 kHz sine wave at 0 dBFS produces a THD + N of 0.00013%, again with second and third-order harmonics below 120 dB from the fundamental.
The 19 and 20 kHz test tones at -11 dBFS produced fairly clean results with minimal sidebands and spurs. The second-order harmonics at 38 and 40 kHz are also very low. It should be noted that this test done at the standard -5 dBFS level caused an overload issue with the DAC, hence our using a lower volume level for this test.
Continuing with the 24-bit/192 kHz tests, a 1 kHz test tone at 0 dBFS presents with a THD+N of 0.00015%. All sidebands along with second and third-order harmonics occur at least 123 dB below the fundamental.
The same excellent results can be said of the 10 kHz test tone at 0 dBFS. THD+N is 0.00027%. All distortion products are completely inaudible appearing at greater than 123 dB below the fundamental.
The 19 and 20 kHz test tones at -5 dBFS also look pretty good with sidebands on either end of the fundamentals occurring at greater than 120 dB below the fundamental. The second-order harmonics at 38 kHz and 40 kHz clock in at 115 dB and 120 dB below the fundamental respectively.
The digital frequency response measurement uses a 24/192 line sweep tone from 10 Hz to 96 kHz. It should be noted that the warble in the line just past 20 kHz is an anomaly in my measurement rig as it shows up in all my frequency measurements with SpectraPLUS. The response is quite flat out to 50kHz after which things begin to slowly start rolling off. By 90kHz we are down about 4 dB after which the roll-off becomes steep.
Since the Focal Arche can perform double duty as a stand-alone preamp as well, I went ahead and tested the analog performance using the RCA inputs (the only analog inputs) and XLR outputs. I did tests with the RCA outputs as well and the results were similar to these when done at 2 Volts standard level. A 1 kHz test tone at 0 dBFS presents with a THD+N of 0.001%. We have some ground noise and a few harmonic spurs with second and third-order harmonics occurring at 106 dB and 111 dB below the fundamental. The low-frequency spurs are line hum and its associated harmonics and may well be an artifact of the measurement system’s grounding. The extension of the spurs beyond 300Hz is more likely from the Arche itself, but without an XLR input to test and confirm we cannot make a definitive statement. This applies to the next three figures.
The 10 kHz, 0 dBFS sine wave produces a THD+N of 0.00085%, again with some ground noise and harmonic spurs. Second and third-order harmonics occur at 109 dB and 107 dB below the fundamental.
The 19 and 20 kHz test tones at -5 dBFS present with some ground noise but also with sidebands occurring at least 120 dB below the fundamentals.
The IMD (Intermodulation Distortion) test consists of a 60 Hz and 7 kHz sine waves and the Arche’s analog section produces an IMD result of 0.00026%.
The frequency response results of the Arche’s analog section essentially mirror what we got from the digital section which is very good.
This digital filter test, first suggested by Jurgen Reis of MBL Germany and used by John Atkinson of Stereophile is designed to give us a look at the type and performance of the digital filter that a given DAC uses. Unique to John Atkinson’s presentation is applying the Reis white noise only in the right channel. In the left channel is a 19 kHz tone. This tone will produce reconstruction spurs if the digital filter is not sharp enough to attenuate them.
Note that John Atkinson uses a 19.1 kHz tone which produces a symmetrical first reconstruction spur at around half the sampling rate (22.05 kHz). That is so insightful we decided not to reproduce it exactly and just go with 19 kHz which is a frequency typically used in a test for reconstruction spurs. Here I’ve combined the results with the corresponding square wave that the filter would generate, for comparison.
The square wave response shows a symmetric FIR filter with a linear phase. This time-domain response should translate to a digital filter with a sharp transition band and deep stopband and that is exactly what we got. The filter is flat past 20 kHz and the stopband drops 60 dB down in this spectra. The Ries test, using our ADC and spectrum analyzer software, may not find the absolute stopband rejection value and, in reality, it may be larger than -60 dB.
The first alias spur is at 25.1 kHz for a 19 kHz tone. It is down a splendid -117 dB from the 12 dBV level of the 19 kHz tone. This is a well-engineered filter!
Note that we are using a 200 Hz square wave to ensure that a filter with a long impulse response has fully settled. Unlike a test performed with a single impulse shot, which can ring down for as long as the filter keeps going, with a square wave we need to leave enough time before the transition. With a 200 Hz square wave, the time between transitions is 2.5 msec.
Having taken the square wave down to 200 Hz we see a small tilt in its shape. The typical 1 kHz square wave response does not show the tilt, but with the frequency reduced by a factor of 5, it becomes visible. This is the high pass response of the analog stage. In order to be flat, no DC blocking cap would have to be in the signal path. Sending DC to the preamp is not a friendly thing to do. With a giant electrolytic, as the DC block, the high-frequency cutoff could drop below 1 Hz making for a flat square wave. The designer chose to go with a smaller film capacitor which is more linear. The cutoff is at a higher frequency but still subsonic.
Using a -90 dB 1kHz test signal, we determined the digital SNR (A-Weighted) of the Focal Arche to be 114 dB (just 2 dB shy of spec). Converted to bits that means the Arche’s digital section can resolve 19-bits.
Here is a time-domain response at -90 dBFS of the Oppo BD-105D that we will use as a reference. Note that we are using a 250 Hz sine wave and not the standard 1 kHz. This is because the QA401 spectrum analyzer/oscilloscope samples at 48k samples/sec in its low noise mode. At this slow sampling rate, a 1 kHz sine wave would not have enough sampling points to be clearly seen.
I can see the techy folks laughing at using a scope with such a small sampling rate. Stop laughing. The QA401 triggers, as we will see on 10 uVRMS waveforms, and has a 22-bit self-noise level.
This is a time-domain plot of a -90 dBFS signal applied to the Focal Arche on the left channel. The self-noise of the QA401 spectrum analyzer in time-domain mode is shown on the right channel. The right channel is grounded. The QA401 can be seen to have a low noise level but this is no state of the art Audio Precision analyzer.
If a noise-free sine wave was applied to the right channel we would see the self-noise riding on the wave.
The best result we have gotten in this test is from our Oppo BDP-105D. This is shown above the Focal result. The BDP-105D has an A-Weighted signal to noise ratio of 124 dB while the Focal is a much lower 114 dB. You can see how much cleaner the Oppo’s -90dBFS sine wave is, given the better SNR. The amplitude of the signal is 123 uVRMS
We are now doing something which may not have been in print before for a DAC box test. We dropped the level of the sine wave to -100 dBFS or 0.31 the size at -90 dBFS. The sine wave has an amplitude of 36 uVRMS.
We scaled the -100 dBFS sine wave by a factor of 3 so its amplitude takes up the same space as the -90 dBFS wave shown above. You can see how the noise of the Focal is more present for this smaller wave.
Note the right grounded channel (self-noise of the QA401) line width has increased by a factor of 3. This is the result of increasing the gain of the oscilloscope by 3.
We take the digital input down another 10 dB to -110 dBFS which drops the level by another 0.31. Again the screen was magnified by 3 to make the wave look the same size as the two that preceded it. The noise of the Focal is making the sine wave harder to see but is still visible above its noise floor. The amplitude of the sine wave is at 12.5 uVRMS.
Again note the grounded right channel with the oscilloscope’s self-noise. The width has also grown by 3 but it is still much lower than the noise generated by the Focal Arche.
We take the digital input down by another 10 dB to -120 dBFS. This is another reduction of 0.31 and the oscilloscope gain has been increased by 3.
-120 dB is equivalent to 0.00001 of full scale. A million to one. The amplitude of the full scale 0 dBFS tone out of the Focal is 4VRMS so the size of the output at -120dB down is 4 uVRMS.
At this level the self-noise of the Focal is larger than the sine wave, making it impossible to see. Obviously, such small sine waves are well below the limit of hearing.
The above graph shows the relative line linearity performance of the Focal Arche. The dual AKM AK4490 DAC chips show minimal amounts of deviation until we arrive at -140 dBFS in level. And even then the change in linearity is minimal. This is a superb performance.
The final spectrum is the Julian Dunn J-Test for jitter at a sampling rate of 44.1k samples/sec.
The test is close to an 11 kHz tone at –3 dBFS down and is a small, low-frequency square wave that creates activity in the PCM data which makes it harder for the clock recovery circuit to produce a clock without some phase noise. I used a 16-bit test generated by REW introducing the square wave at an amplitude of the smallest level possible for 16-bit data which is called the least significant bit. An excellent explanation of the J-Test and the spurs the test produces can be found here).
John Atkinson identifies the spur’s amplitude and frequency of the J-Test in absence of jitter. John then comes up with an innovative line to be placed on a spectrum of the analog output of a DAC box which is reproducing the J-Test. Any spur below the line is inherent in the test and not from the DAC box.
As can be seen, the jitter of the Focal is below the limits of the test. The small residual spurs between the line are small enough that we cannot tell if it is Jitter from the Arche’s DAC or the ADC we use to translate the signal back to digital to produce the spectrum.
Stellia Headphones and Arche AMP/DAC
- Balanced, natural, and open sound quality.
- Beautiful design and finish
- Very easy to drive.
- They feel and sound expensive.
- Plenty of power to drive most headphones.
- Fairly clean DAC section.
- Can be used as a DAC or Preamp on its own.
- The built-in headphone stand is genius.
- Slightly better DAC performance in the Arche. It’s very good but not quite state of the art.
- A pair of balanced XLR inputs for the Arche.
- XLR to 4-pole 2.5mm (or comparable) adaptor for the Stellia. For portable balanced operation.
Within the world of audio, the headphone and personal audio space continues to see exceptional diversity in product and sales growth, even in these unusual times that we find ourselves in. A few years ago, spending $3000.00 on a pair of headphones, even if it was a product with luxury aspirations, was considered excessive, bordering on outrageous. Today that price for a pair of elite cans is not even viewed as shopping the top tier of the market. If you are looking at products in this price bracket, or even a little higher, you owe it to yourself to seek out and spend some time sampling the Focal Stellia headphones. From a sonic perspective, there was precious little that I found wrong with them. Their balanced and natural presentation worked well with all manner of music and I didn’t feel that they were noticeably over- or under-representing any particular part of the frequency spectrum during my listening. They are exceedingly easy to drive with a smartphone or DAP, but are transparent enough to audibly benefit by using something with a better quality DAC section. For your investment, you get a product that uses advanced materials, in the way of Beryllium for its drivers, and acoustical tuning along with some of the best quality surface materials and fit & finish that I have encountered in a headphone. I also found their design and color scheme to be particularly unique and attractive. The Stellias look, feel, and sound special.
The accompanying Focal Arche headphone amp and DAC is a well thought out, powerful, and flexible control hub for all manner of headphones and, through it’s customized presets, is especially suited for any of Focal’s Hi-Fi cans. The Arche’s built-in headphone stand is a brilliant convenience feature, the unit produces ample amounts of power to drive virtually any headphone and, if used as a standalone DAC or preamp, can cleanly drive other downstream home Hi-Fi components. Bought on its own for ($2500.00), the Arche faces legitimate competition from similar products that, frankly, undercut its price and match its performance. But when taking advantage of the significant savings that Focal offers when bundling the Arche with a qualifying headphone purchase (or the $1000.00 voucher if you are an existing Clear, Stellia or Utopia owner), it’s hard to pass up unless you already own something significantly better.
At the end of the day, the Stellia is a reference-quality pair of headphones that I highly recommend. The Arche is a fine quality and worthy companion to drive and enjoy the Stellias with. In many ways, they are like chocolate and peanut butter. Almost better together.
The author would like to thank David A. Rich for his assistance with this review.