Note: for the full suite of measurements from the SoundStage! Audio-Electronics Lab, click here.
In this strange time of instant gratification, instant retrieval of information, same-day delivery of purchased goods, and honest-to-god artificial intelligences, it’s good to slow down and return to a simpler age. I’m not suggesting that you start to churn your own butter, but sometimes it’s good to turn off all that stuff and subtract a century from your lifestyle, if only for a few hours.
I think you know where I’m going with this. What better way is there to lower your blood pressure than sit down and listen to music via a tube amplifier? And if you’re really intent on rolling back the odometer, you might as well make it a 300B tube amplifier.
Triode tube amplifiers, of which the 300B triode is the poster child, are edge cases in the world of hi-fi. They’re extremely low powered—generally squeaking out about 7W per tube, downhill, with a tailwind—which rules out most speakers. And my, oh my, do they measure wonky. This means that they can sound wildly different, depending on the impedance of the speakers you do choose.
There’s a payoff, though. If you accept the limitations of these nutty amplifiers, and the planets align, you’ll reap an incredibly rich, flavorful midrange and a sweet, relaxed treble.
Not enough power, you say? How about we double up on those 300B tubes, running them single-ended but two per channel in parallel? That’s what I’m looking at and listening to right now. Fezz Audio, which I first encountered at the 2022 Audio Video Show in Warsaw, Poland, recently sent me their Lybra 300B integrated amplifier ($5995, in USD), and it’s an absolute sweetheart.
Fezz Audio is an offshoot of Toroidy, a Polish transformer manufacturer. Iron—an essential ingredient of transformers—has been mined for and produced in Poland for over 2000 years. Toroidy is one of a number of companies in modern-day Poland to exploit that heritage. So what else can you do when you’ve got a thriving transformer-manufacturing facility? Start making tube amps, of course. And here we are.
The Lybra has two 300Bs per channel, which bumps up the output from the punky 7W you’d expect from a single tube to a claimed 15Wpc. From my viewpoint, 7Wpc just isn’t enough for real-world use—but just over double that? Depending on the speakers, it could work fine.
The Lybra is an attractive unit, with a much more sophisticated presentation than the utilitarian bent-metal chassis sported by most integrated tube amps on the market. The front and sides of the main chassis are formed from a single piece of 3mm (1/8″) powder-coated steel, with softly rounded corners. The smooth lines of the Lybra’s chassis—available in a range of matte colors—help the amp stand out from the crowd. My sample had a finish Fezz calls Sunlight: a sort of golden tan. The cherry-colored Big Calm finish displayed on the company’s website looks especially tasty. The top, bottom, and rear panels are also machined from 3mm steel, which gives this 52-pound amplifier a solid, of-a-piece feel.
Accounting for a large chunk of that weight are the transformers lurking under their cylindrical covers. In any tube amp, the transformers are the main event—the rest is just busywork, given that this is a mature design dating back more than 75 years.
The four slightly squishy feet underneath the amp proved problematic. My colleagues Doug Schneider and Diego Estan had the Lybra before I did, for photography and measurements respectively. Both of them noticed stains from the rubber feet on their wooden equipment racks. Forewarned about this, I used a cork disc under each foot to protect my solid-walnut rack.
Earlier this year I participated in a Zoom meeting in which Fezz Audio’s CEO, Maciej Lachowski, and his brother Tomasz, CEO of Toroidy, presented their amplifiers to EISA members. Maciej pointed out that the transformers used in the amps are manufactured to their own specifications, and that there are a number of benefits to using toroidal transformers rather than the EI-core transformers traditionally found in tube amplifiers.
It turns out that toroidal transformers maintain proper operation over a wide frequency range, starting below 20Hz and reaching above 100kHz, and at the same time guarantee an ultra-flat frequency response within the 20Hz–20kHz range, with a very low level of harmonic distortion.
According to Maciej Lachowski, the high efficiency of toroidal transformers is mainly due to the shape and the directional molecular structure of the core, which is consistent with the direction of flow of the magnetic flux. A toroidal transformer requires much less energy when operating in standby mode. The energy consumed at idle is 16 times lower than a classic EI-core transformer, he said.
Furthermore, a toroidal transformer has one-tenth the magnetic-field emission of a traditional transformer, and dramatically lower mechanical noise. The windings of a toroidal transformer cover the magnetic core exceptionally well, shielding and concentrating the flow of the magnetic field within the core. As a result, toroidal transformers can be used in extremely sensitive electronic devices that operate at low signal levels.
As I stated earlier, there are two 300B tubes per channel. These are Psvane tubes, sourced from China; understandable, given the current embargoes on Russian products. The driver stage consists of three RC-coupled voltage amplifiers, cascaded to provide the gain required to drive the 300B output valves. One 6SN7 triode and one-half of a 12AX7 are used in each channel.
Parts inside the Lybra are well chosen but not extravagant. I didn’t unbutton the amp, but Maciej Lachowski informed me that the Lybra employs high-quality metalized resistors; Nichicon, EPCOS, and Miflex capacitors; and an Alps potentiometer. Where it gets interesting, however, is the Toroidy-made inductors used in all Fezz amplifiers. By way of Toroidy’s magnetic-core production technology, the Lybra is fitted with toroidal chokes, which, according to the company, outperform conventional iron-core inductors. Compared to traditional EI-core chokes, Toroidy’s toroidal chokes are characterized by minimal magnetic-field dissipation, minimal mechanical vibrations, and much lower DC resistance.
The Lybra has three pairs of well-made, chassis-mounted single-ended inputs, and nice-looking speaker binding posts for both 8- and 4-ohm taps. Power is delivered via an IEC socket, and there’s a decent cord supplied in the sturdy shipping box.
The tube cage deserves special note. It has a clear Plexiglass front panel that delivers an unobstructed view of the tubes. The cage slides on from the front and catches on two raised screws that hold it securely in place. It’s quick and easy to install and remove, and it’s a clever, sanitary design.
Setup was straightforward. The Lybra is auto-biasing, so just stick the four power tubes into the sockets, hook up power, speakers, and sources, and you’re in business. The power switch is on the rear of the chassis, which may be problematic if you’re installing the amp in a cabinet with limited access. Not so in my system: I mounted the amp out in the open, on the top shelf of my equipment rack.
Flip the switch and the Lybra goes through a short warm-up cycle, during which the Fezz insignia on the center of the front panel lights up a dim red. After a minute or so, the light turns blue and the amp is good to go.
This is one seriously quiet tube amplifier. There was effectively zero noise through any of the speakers I used. Like, none. If I put my ear up to the tweeter with no music playing, I could detect just the tiniest bit of hiss, but seriously, it was so low in level that I really had to strain to hear it. Moving more than 2″ away from the speaker, the Lybra was utterly silent.
After a short listen—maybe an hour or so—one tube went all sparkly, like it was running a Star Trek transporter inside. The corresponding channel also started to distort. The distortion was quite low in level—the tube was obviously failing, but it had the grace to do so in a polite manner. After I replaced it with the new tube that Fezz shipped to me, the amp fired right up and worked flawlessly for the rest of the review period.
My review sample had been around the block—originally shipped from Bluebird Music, Fezz Audio’s US distributor, to Doug Schneider, then over to Diego Estan’s place, and finally to my house. The failed tube rattled when I shook it, so it was obviously a physical failure and not related to the amplifier. Conversely, the Lybra’s controlled response to this failure points to the amp being quite rugged and well designed.
Once up and running, I found that the Lybra needed a good 20 minutes to warm up. On initial startup, the amp sounded a bit thin, bright, and constipated. But after one album, it opened right up.
I initially hooked the Lybra up to a pair of Estelon XB Mk II speakers. I wasn’t really sure that this would be an appropriate match. The XB is a large, three-way speaker with specified sensitivity of 88dB (2.83V/1m). So it was questionable whether the Lybra had sufficient grunt to drive it. Add in Estelon’s recommendation of a minimum 30Wpc of power—exactly double the Lybra’s rated output—and things were looking dicey. Still, it was worth a try.
The first record I played was Pale Sun, Crescent Moon, by Canada’s Cowboy Junkies (LP, RCA 190758647913), and the memory of the weight, the drama, of “Pale Sun” on side 3 will remain with me for a long time. Admittedly, this track—heck, the whole album—is miles deep and aromatically atmospheric, but with the Lybra driving the Estelons, the sound was so juicy, so wet, so full of rich gravy, that it made my eyes go misty.
Stay with me here. It’s been a while since I’ve had a tube amp in my system. My last long-term tube amp was an older Audio Research VT100 that unfortunately experienced a meltdown some years back and proved to be unrepairable. I’ve always loved the classic tube sound, but I switched over to solid state as it was more conducive to consistent, reliable reviewing. So I was anticipating that my time with the Lybra would be a sort of hedonistic, wretched-excess holiday, like falling backward into a giant tub of warm honey. I expected lushness. I expected texture.
I did not expect the immediacy and depth of image of Margo Timmins’s voice. It was like I was looking right down her throat, right into her soul. Oh sure, I got more richness through the midrange, and an increased feeling of roundness to the actual body of her voice. That said, the sound wasn’t the sepia-toned, overt romanticism that I was expecting from this amp.
The density of the sonic images through “Pale Sun” was simply breathtaking. That distorted, wailing guitar at the start, the way it builds and rises from an inkwell silence—through the Lybra, it gained a palpability that took my breath away.
As expected, there were a couple of compromises with this amp-speaker matchup. The bass was rounder, fuller, less discrete. The Estelons are capable of gut-smacking bass. As my compatriot and fellow SoundStager Roger Kanno once said when speaking about a subwoofer, it’ll suck the air right out of your lungs. But that’s with a rock-busting solid-state amplifier. Via the Lybra, I lost a fair bit of the definition on the leading attack of bass notes.
Swapping over to Talk Talk’s The Colour of Spring (LP, EMI EMCX 3506), it was immediately apparent that the opening kick drum on “Life’s What You Make It” didn’t have the snap it should have had. The rolling bass line also didn’t have the articulation that I’m used to. The actual bass level was just fine, but it was more of a continual grumble rather than clearly delineated notes. That said, the loss in bass articulation was a fair tradeoff for—again—the immediacy and increase in space around instruments.
Now, there was an elephant in the room with the Lybra driving the Estelons. This combination would only go so loud. I could crank it up to a good, fun level—just about my normal maximum listening volume—but beyond that, I couldn’t get it to go any louder. There are times when my neighbors are out of town and I want to crank the living hell out of my system, and the Lybra didn’t have the minerals to make it happen. I’d turn the volume dial up higher and higher, and it wouldn’t get any louder. The amp didn’t distort or register any signs of distress, but it was clear to me that I’d reached a limit.
No fault of the Lybra. The amp went as loud as I needed, and considering I wasn’t sure if the Lybra could even make the Estelons squeak, I’d have to say that this pairing was a qualified success.
Just to be fair and equitable in my listening sessions, I pivoted to another pair of speakers I had on hand—Totem Acoustic’s Sky Towers, originally reviewed by Philip Beaudette on SoundStage! Hi-Fi. At a quoted 88dB (2.83V/1m), the Sky Tower is not exactly efficient, but it’s not as complicated a design as the XB and probably more representative of the speakers likely to end up tethered to the Lybra.
To tell the truth, I wasn’t expecting that much from this combo, especially after having listened to the Lybra through speakers that retail for more than 25 times the cost of the Totems . . .
But mother of 12 bastards, what a fantastic sound! Maybe it’s the even, 8-ohm impedance, the simplified crossover . . . Whatever the reason, the Sky Towers just pounded with the Lybra. There was plenty of volume available, up to any reasonable level, and even beyond. Short version—I couldn’t see a need to ever play music louder than this combination could manage.
The switch to the Sky Towers revealed a failing of the Lybra when driving the Estelons. Listening through the Sky Towers, I noticed that the Lybra now handled music with much better, clearer definition between instruments. I realized that I had been drawn to sparse, atmospheric music when the Fezz tube amp was hooked up to the Estelons. As the source material became busy, I had found myself checking out, becoming less engaged.
Not so with the Totems. Much of the inner light, the snap, the sense of immediacy that I just raved about with the Estelons was reproduced surprisingly well by these small, unremarkable-looking towers. Oh sure, a chunk of the detail, the effortless grace, of the larger speakers was missing in action, but here’s the important point: I didn’t feel remotely short-changed by the Sky Towers. I listened happily, for long stretches, enjoying the heck out of these unassuming little guys.
The Sky Towers totally let the Lybra shine. I spun up my Japanese pressing of Supertramp’s Breakfast in America (LP, A&M Records AMP-6034) and “The Logical Song” hurled me back into my high school hallway, fumbling with my Dudley lock as I panicked, late for science class. “Gone Hollywood” is quite busy through the midrange, and unlike my experience with the Estelons, the Lybra kept a grip on the Totems, keeping each instrument discrete within its own space. More than that, the Lybra pulled me into that wormhole, accentuating the leading edge of the notes on the keyboards, fleshing out the overtones on Roger Hodgson’s voice, and adding a wonderful sense of space and depth around that crackling guitar.
And that mushy bass I whinged about earlier? All sorted through the Sky Towers. I threw on Giant Sand’s Cover Magazine (LP, Thrill Jockey THRILL 104) to see how the Lybra would handle Joe Burns’s tasteful, languid bass on the “El Paso / Out on the Weekend” mashup. Within the limits of the Totem’s single 5.75″ woofer, I got the requisite weight and definition that I’ve come to expect from this delightful track. More than that—the Lybra made the little Sky Towers sound far, far larger than I could have ever expected.
I could live with this amp. I would love to live with this amp
Listen: a ton of gear cycles through my system, and I’ve learned to keep my distance, to avoid getting sucked into any feelings of desire—of lust—for the components that sounded really good.
But I’m looking out of the corner of my eye right now at the Lybra, and listening to it with these Totems, I’m having trouble keeping “the fever” at bay. I originally went into my time with the Lybra thinking it’d be so tonally colored that I’d be continually distracted (happily, though) from the music itself.
While listening to the Lybra powering the Estelons, this was kinda true. I loved that combo, but I could clearly hear its limitations—the lack of power, the indistinct bass. Yet, considering the little tube amp only produced half the power (Diego’s measurements will tell the tale) recommended by Estelon, I thought the Lybra did a bang-up job.
When I threw the Totems into the mix, I did a bit of a head-explody. The Sky Towers matched so well with the Lybra that I’ll likely find myself cornering people at parties, poking them in the chest as I insist that they purchase this combination for themselves. The clarity, the extension, the imaging, the flat-out flavor that this amplifier excavated from these speakers startled me and made me re-evaluate the concept of value in audio.
This is Ultra audio, right? So let’s consider, shall we, that there’s a whole constellation of speakers with physical and electrical characteristics similar to the Sky Towers that’d likely pair perfectly with the Lybra while mounting a full assault on the state of the art. You could quite feasibly purchase a Lybra, and—what the heck—a pair of Sky Towers from my Canadian homies at Totem Acoustic while performing a rigorous search for the perfect speakers that hew to your exact tastes.
You’d get no argument from me.
. . . Jason Thorpe
Note: for the full suite of measurements from the SoundStage! Audio-Electronics Lab, click here.
- Analog source: VPI Prime Signature turntable; EAT Jo N°8, DS Audio DS 003 cartridges.
- Digital source: Logitech Squeezebox Touch.
- Phono preamplifiers: Aqvox Phono 2 CI, iFi Audio iPhono 3 Black Label, Hegel Music Systems V10, EMM Labs DS-EQ1, Meitner DS-EQ2.
- Preamplifiers: Sonic Frontiers SFL-2, Hegel Music Systems P30A.
- Power amplifiers: Bryston 4B3, Hegel Music Systems H30A.
- Integrated amplifiers: Hegel Music Systems H120, Eico HF-81.
- Speakers: Estelon XB Mk II, Totem Acoustic Sky Tower.
- Speaker cables: Audience Au24 SX, Nordost Tyr 2.
- Interconnects: Audience Au24 SX, Furutech Ag-16, Nordost Tyr 2.
- Power cords: Audience FrontRow, Nordost Vishnu.
- Power conditioner: Quantum QBase QB8 Mk.II.
- Accessories: Little Fwend tonearm lift, VPI Cyclone record-cleaning machine, Furutech Destat III.
Fezz Audio Lybra 300B Integrated Amplifier
Warranty: Two years, parts and labor; 90 days on tubes.
Kolonia Koplany 1E
16-061 Juchnowiec Kościelny
Phone: +48 724 430 404
Bluebird Music Ltd.
310 Roswell Ave.
Toronto, ON M4R 2B2
Phone: (416) 638-8890