A Fyne Audio SuperTrax supertweeter atop Gautam's T+A Elektroakustik TCD 210 S loudspeaker. Photos by Jordan Perez.
Our content manager, Gautam Raja, lives with Fyne Audio's supertweeters to see if ultra-high performance is a thing.
My favorite audio moments are when I’m skeptical about a product that proceeds to take a can opener to my skull and completely open my mind. This just happened to me with supertweeters, specifically the Fyne Audio SuperTrax and S-Trax, which I brought home to try in my main rig and my office system.
Have you been to Crater Lake? You can’t see the bottom, but the way the light falls off as you look down into the crystalline waters tells you it is extremely deep. I think of Crater Lake when I hear supertweeters. I may not be sensing 60 kHz, but the way the top end sparkles up into the void makes music playback so much more beautiful and realistic. Joel Bennett, my colleague in sales, described the experience as a “breath of clear mountain air”.
But before we go any further, let’s get some ultrasonic myths out of the way.
It’s Not (Just) About Ultrasonics
Bats and Dogs
When the armchair forum experts hear of any speaker system that extends past 20 kHz, the tired, trite comeback is “Only dogs and bats can hear that.”
This shows a profound misunderstanding of why an engineer would extend the linearity of any system beyond what’s considered a normal or useful range. A tweeter that’s acceptably linear to 20 kHz doesn’t perform perfectly to 19.999 kHz, and then fall off a cliff. It starts to exhibit anomalies well before 20 kHz, with resonant effects reaching down into the audible zone.
A tweeter that’s acceptably linear to 60 kHz, meanwhile, will exhibit major anomalies well out of the traditional audible band, with smaller effects downstream. (Of course, good crossover design mitigates these issues in the audible band.)
Old Men
A continuation of the misconception that ultrasonic extension is only about hearing ultrasonics, is the idea that a supertweeter is only for older listeners who have lost high-frequency hearing. As we’ll see later, the biggest improvement from a supertweeter is its phase correction, and not the increase in volume above 16 kHz. (Both Fyne supertweeters have a frequency response of 16 kHz to 50 or 60 kHz, depending on the model.)
The Supertweeter’s Killer App
While supertweeters certainly add air and sparkle, their killer app is the linearization of phase response. But how can a supertweeter "fix" loudspeaker anomalies when it doesn't directly lighten the load on the tweeter?
Simplistically, the full-frequency sound coming off your speakers should be like this | but instead is like this ) where the highs and lows near and beyond the speaker’s -3 dB or -6 dB cut-offs are delayed. (The factors that cause high- or low-frequency roll-off are, effectively, filters, and filters slow down frequencies near their cut-off frequency.) You can see how there’s a gap caused by the curve of the parenthesis on top and bottom; a gap that can be filled in by another speaker driver launching with the main signal, thereby time-aligning the entire wave. We regularly do this at the bottom end with a subwoofer, which is why the benefits of a sub go so much deeper than “more bass”. Similarly, think of the supertweeter’s matching up-top contribution as less about “adding highs” and more about anchoring the timing of the top end by filling in the upper part of transients that begin well below 16 kHz.
All supertweeters can correct for phase, but Dr. Paul Mills, Fyne's technical director, has added a brilliant twist to the Fyne Audio design by pointing the driver upwards at a tractrix cone, allowing for 360° dispersion. (This is exactly the same principle as BassTrax, which Fyne uses for its bass ports across all its speakers.)
This 360° dispersion isn’t simply to increase the supertweeter’s spread, but to compensate for the beaming of your loudspeaker's tweeter at higher frequencies. Dr. Paul sums it up thusly: “It’s not just frequency response we have to consider, but both phase error and the reduced dispersion with increasing frequency, that affects the total energy into the room.”
What Does It Sound Like?
I brought home a pair of the Fyne Audio SuperTrax and set them up on the conveniently flat glass tops of my T+A Elektroakustik TCD 210 S floorstanders. I used the spade connectors of the Fyne SC1 cable to share the speakers’ high-frequency binding posts with the bananas of my AudioQuest William Tell bi-wire cables.
Gautam performed extensive listening sessions with the SuperTrax in his main system.
Rather than talk about all my test tracks, I’m going to lead you through the first minutes of one of my all-time favorites, describing exactly what I heard. At this point you might wonder, can you directly hear the supertweeter? Yes, if you turn it up and get your ear right up to it, you can hear a thin signal. In the listening position, if the gain is too high, you hear it as sibilance and hissiness.
The very first impression was one of smoothness. I have solid-state gear in a challenging A-frame room, and immediately felt like I had lost top-end harshness.
The test track I've chosen is 'Boogie Street' from Leonard Cohen’s Live in London. I like to have a live track on my test list and listen for changes in the crowd noise as I improve the system. Over the years, clapping has gone from white noise to individual handclaps; whistlers, hooters, and shouters stand out more; the space of the arena is more evident, and the crescendos of the crowd are more bearable.
Live in London is so well recorded, you forget that it’s only CD-quality. It’s a document of a beautiful evening, and both my wife and I have often wished we’d been there. (Were you there? Write to gautam@upscaleaudio.com and make me jealous.) Also, full disclosure: When I upgraded from my Lumin U1 Mini streamer to the U2 Mini, I finally liked the sound of upsampling, so this 44.1 kHz track is being upsampled to 176.4 kHz. (Similar to the supertweeter's effect, upsampling isn't used to add information that isn’t in the original, but to move the digital filters way up high, making the response more linear through the audible band.)
Over many listenings, where I jumped up and down, adding and subtracting supertweeters, I made a list of exactly what the SuperTrax was bringing.
0:00–0:20: From the opening “whoo hoo” to the first claps, whistles, and cheers, each sound is clearer, more separate, and the handclaps smack harder. The whistles are more piercing. Sharon Robinson is a steadier image in front of me, and I register for the first time, the throatiness of her exhalation at the end of “Oh crown…”.
0:20–0:40: The keyboards have more attack and sit in their space better. The “mmm” of the Webb Sisters is more clearly two separate voices. All intakes of breath are much more noticeable. (Far from being distracting, it makes me feel I was there.) Decays of instruments hang in the air like mist.
1:20–1:30: The bass comes in nice and tight, making it clear that cleaning up the top end declutters down to the floor. The saxophone has more dance and bite, and its image is more solid. Over the years, I’ve heard Leonard Cohen saying, “Sharon Robinson wrote this tune” get ever clearer, and this is the clearest it’s been.
1:36: I listen here for the tone of the bass guitar as the player changes notes. It’s when you really hear it as an instrument beyond the bass thump, and this is the best I’ve heard it.
Finally, when I sit back and just listen, I can hear that the soundstage has gone from proscenium to thrust. The scale of the image before me feels boundless.
The “Secret” Supertweeter Benefit
So that was the second-by-second “critical listening from the sweet spot” benefit of a supertweeter. I don’t know about you, but I spend a lot of time doing casual listening. With the system in a lower section of the front room, my wife and I often sit alongside and a little above it at the dining table, playing music while we drink chai and read the newspaper. (Yes, we still subscribe to a print newspaper.) I spend hours a week just around a corner from the speaker plane in the kitchen, prepping meals and cooking, while Radio Paradise or a favorite album blasts.
My finding is that with the 360-degree dispersion of Fyne supertweeters, and because of the supertweeter’s ability to nail down the timing of a delayed or dispersed signal, you get more of that sweet-spot coherence even when severely off-axis. This is a huge real-world benefit of Fyne supertweeters that Fyne should be banging on about a lot more.
Before trying out the more affordable S-Trax, I would have placed a supertweeter very low on a list of suggested upgrades to a mid-level system. Now, I’d actually recommend them as part of your initial system build. The core that's source, amplification, speakers, speaker cables, and interconnects always come first, as you can’t have music without them. My close second list is now: rack, subwoofers, supertweeters, and power upgrades.
As far as I'm concerned, this is huge. Supertweeters are not mere toys for the idle audiophile, but a serious upgrade that significantly enhances even casual listening.
Meet the Top Performers
With the recent launch of S-Trax, Fyne Audio offers two supertweeter models. While both are designed to match Fyne loudspeakers, they will work with most brands and models that have up to a 98 dB sensitivity.
Fyne Audio SuperTrax ($4,499/pr)
Not cheap. But intended for Fyne's best, as well as excellent speakers from other brands. The walnut and brass finish perfectly complements Fyne’s Vintage series, while the gloss-black and chrome matches Fyne's F1, as well as other contemporary designs. You can see they look totally at home on my T+A speakers.
The gentle arch on the SuperTrax solidly supports the tractrix cone above the driver.
A gentle arch stabilizes the tractrix cone, and the 25 mm carbon-ply driver is nestled under a protective trim-ring and grille. The 10” long footprint means exceptional stability against cats and dusters. Frequency response is 16–60 kHz (-6 dB), and the gain knob offers ±3 dB of control. Grounding is an option if your loudspeaker has a ground post. The SuperTrax undergoes Fyne Audio’s full cryo treatment.
Fyne Audio S-Trax ($1,299/pr)
The S-Trax might be the inexpensive version of the SuperTrax, but doesn’t look or feel anything like a budget product. It has a dense heft in hand with the metal tractrix cone solidly mounted on three columns, and a mesh grille protecting the magnesium dome driver. Though it has a much smaller footprint than the SuperTrax, its density ensures it sits just as solidly atop your loudspeaker.
The Fyne Audio S-Trax has a dense heft that belies its budget status. Photo courtesy of Fyne Audio.
Frequency response is 16–50 kHz, and the gain knob offers ±4.5 dB of control. There’s a ground post, and the S-Trax undergoes Fyne Audio’s CryoLite treatment.
Switching between the SuperTrax and S-Trax will involve further (and rather complex) listening sessions, so we confirmed with Dr. Paul that with the S-Trax you’re really only missing that last bit of air and detail. “You just get more of the ‘magic’ with the SuperTrax,” says Dr. Paul. Initial listening suggests this, albeit with the S-Trax being far better than expected.
The Final Word
The "even my [non-audiophile partner] heard it" story on forums is often assumed to be a fabrication to prove that something inaudible was actually audible. But, for me, it really happened. With her back to the system one recent morning, unaware I'd added the supertweeters, my wife said the sound was "really nice," specifically mentioning that the midrange sounded better. Over the weekend, she continued to wholeheartedly approve of what the supertweeter was doing. "The tweets are tweetier," she said at one point, so that's what I'll leave you with:
Get a Fyne Audio SuperTrax or S-Trax and make your tweets tweetier!