Esoteric’s F-03A integrated amplifier proves the audio truism that not all watts are created equal. With an output power of just 30Wpc, the F-03A isn’t anyone’s idea of a powerhouse. Yet the F-03A’s 30 watts are not only among the sweetest sounding you’ll find; they are also far more potent than those of lesser-quality amplifiers with a similar power rating. The F-03A’s sweetness is provided by its Class A operation, the potency from its robust output stage and power supply. Two amplifiers with the same power rating into 8 ohms “on paper” can have radically different real-world performances. One can sound anemic; the other can sound like an amplifier of nearly twice its rating.
In listening to the F-03A for many months through a variety of speakers I can say that for 90% of my listening those 30W were more than adequate. I suspect that the F-03A would similarly satisfy many listeners who wouldn’t have considered an amplifier of “only” 30Wpc. That would be a shame, because the F-03A is an outstanding product that shouldn’t be summarily dismissed from a glance at the spec sheet or an evaluation by the “watts per dollar” criterion.
The F-03A is a gorgeous piece of audio hardware, with lavish chassis work that befits the Esoteric marque and the integrated’s substantial $13,000 price tag. It’s packed with useful features, and in its control and operation is never less than stellar. It has a luxurious, premium vibe, from the tactile feel of the ball-bearing-mounted volume and source-selector knobs to the way the fold-down door gently glides open to reveal seldom used controls.
The front panel is dominated by a large volume control, identically sized source-selector knob, and a useful alphanumeric display. The fold-down door reveals an extensive feature set including selectable phonostage gain, a balance control, three-band tone control, and an A/B speaker switch. A mute control and ¼” headphone jack round out the front panel.
The F03-A’s more advanced features are accessed through a menu system and the front panel display. These features include the ability to select a default volume level for each input, invert absolute polarity independently on each input, name the sources in the display (“DAC” rather than “BAL 1” for example), configure the unit as a preamp or power amplifier, adjust the display and knob backlighting, and set one or more inputs at unity gain as a home-theater pass-through input. The F-03A’s amplifier section can be driven by an external preamp, or you can tap into the F-03A’s preamp-out signal to drive an external power amplifier. I used these preamp-out/power-amp-in jacks to connect a JL Audio CR-1 subwoofer crossover for some of the audition.
The rear panel reveals a generous input and output complement. Two balanced and five unbalanced inputs are provided, along with balanced power-amp-in jacks and both balanced and unbalanced preamp-out jacks. A rear-panel opening can accept an optional DAC board ($1200) that is compatible with any PCM format and DSD up to 11.2MHz.
The comprehensive remote control fits nicely in the hand; it can also control Esoteric’s disc players.
The design and construction are lavish, as you’d expect in a $13,000 30Wpc integrated amplifier. The F-03A is a distillation of circuits created for Esoteric’s über-expensive Grandioso series, with a fully balanced preamplifier section, dual-mono construction, a switched-resistor attenuator (volume control), and the ball-bearing volume and source-selector knobs mentioned earlier. A fully balanced design requires double the circuitry in the preamp section, but results in lower noise and distortion. It also requires a four-element volume control (left +, left –, right +, right –). Rather than accept the noise and level imprecision of a potentiometer, Esoteric developed the Quad Volume Control Systems (QVCS), an attenuator built from switched-resistor networks. The volume knob controls an encoder that selects a combination of resistors from a resistor-ladder network to realize the precise amount of attenuation for all four signals. It’s vital in a balanced circuit that the + and – signal paths are identical in level, and QVCS assures that precision.
The output stage is a scaled-down version of that in the flagship Grandioso S series, with three pairs of the same output transistors as in the $40,000-per-pair Grandioso M1 (see Alan Taffel’s review of the Grandioso M1 in Issue 280). A beefy 940VA power transformer accounts for much of the F-03A’s 71-pound weight. The robust output stage, oversized transformer, and 40,000 microfarads of filter capacitance allow the F-03A to double its 30W 8-ohm rating when driving 4 ohms. An amplifier’s ability to double its output power when the impedance is halved has real-world performance benefits, particularly in reproducing music’s dynamics as well as delivering a solid, tight, and extended bottom end.
The casework and overall construction are no less impressive. Separate compartments within the thick aluminum chassis isolate subsections from each other and are arranged for the shortest signal paths. Custom multi-part machined feet isolate the F-03A from vibration.
For those who need more output power, Esoteric offers the F-05 at 120Wpc. I suspect that the $10,000 F-05 is identical in every way to the F-03A except that its output stage is biased to operate in Class AB rather than in Class A. The F-05 also lacks the F-03A’s drop-down door, and its isolation feet are less elaborate. (It turns out that the circuitry is indeed identical, but the transformer potting method is different between the F-03A and F-05.) The third model in the “F” integrated amplifier series is the F-07, which despite its higher model number, is the least expensive of the trio at $7500. It outputs 100Wpc, with cost saving realized by employing a smaller power supply, less thick faceplate, two-band tone controls rather than three, and a few other minor design features of the other two models.
As my “daily driver” for the past eight months, the F-03A was a joy to operate and to listen to. I chose the F-03A for review because I wanted an integrated amplifier that was musically satisfying as well as transparent enough to evaluate other products while I’m in my temporary scaled-down listening space. The F-03A fit the bill on all accounts. As I said at the start of this review, it would be a mistake to summarily dismiss the F-03A because of its modest power rating. Although it won’t deliver the ultimate in dynamics and bass extension with difficult-to-drive speakers, there are plenty of loudspeakers for which the F-03A’s output power will be sufficient. A speaker of 88dB sensitivity or greater should be a good match for the F-03A. When driving the 90dB-sensitive Monitor Audio Silver 300 or the 91dB-sensitive Piega Coax 711, the Esoteric never sounded strained. In fact, the bass was outstanding, with a wonderful combination of solidity in the lowermost octaves and excellent control and definition in the mid and upper bass. A good example is the track “Teen Town” from bassist Brian Bromberg’s album Jaco, a tribute album to his musical hero. The piece features Bromberg playing a bass line in the instrument’s lower register, and then overdubbing the lead line on the instrument’s highest register. The F-03A provided both the tonal foundation of the bass line with the pitch definition and articulation of the lead bass line. In addition to this solidity and weight, the Esoteric beautifully reproduced the texture of the bass along with its attacks and decays in a way that brought the instrument to life. The bottom end had real definition and expression, not just sounding like low frequencies. That’s my experience with speakers of average to highish sensitivity; I nonetheless recommend that you audition the F-03A with the loudspeakers you intend to drive with the F-03A before making a purchasing decision. I suspect that most listeners will be pleasantly surprised at just how dynamic and potent 30W can sound. Also keep the relationship between speaker sensitivity and amplifier power in mind: Every 3dB increase in speaker sensitivity is equivalent to doubling the amplifier power.
But the F-03A’s bass, though excellent, isn’t the F-03A’s raison d’être. This amplifier lives to deliver a sweetness and purity in the mids and treble that rivals that of very expensive Class AB powerhouse amps. There’s something about the sound of a pure Class A amplifier that is particularly beguiling. Class A in general, and the F-03A in particular, doesn’t sound like Class AB solid-state, but neither does it sound like tubes. The F-03A, like other Class A amplifiers I’ve heard, lacks the patina of transistor artificiality that overlays all but the very best (and massively expensive) Class AB amplifiers. This artificiality is manifested as a slightly dry, whitish, mechanical character in the midrange and treble that robs tone colors of their warmth and saturation. It’s this solid-state signature that turns many music lovers toward tubes. But Class A operation generally doesn’t seem to suffer from this affliction; instrumental textures are rich, full-bodied, densely saturated, velvety without being soft, and musically engaging. This isn’t to say that these qualities can’t be realized with Class AB operation, only that they seem to come easily to Class A (just the way bloom, air, and life come so easily to analog). The virtues of the F-03A’s Class A operation were readily apparent on a range of instruments, but were particularly salient on saxophone and vocals. The sax, with the most complex harmonic structure of any instrument (flute has the simplest, that is, the most like a sinewave), is revealing of any thinning or bleaching of tone color. I’ve enjoyed a lot of sax-featured music lately, from old classics such as Ben Webster’s Soulville (a great-sounding MQA remaster on Tidal) to Illinois Jacquet’s Swing’s the Thing (LP reissue), to contemporary masters of the instrument like Gary Meek (Originals) and Chris Potter (Amsterdam Blues). The F-03A’s smooth and suave upper midrange and lower treble beautifully conveyed a natural and unfatiguing tonality of this difficult to reproduce instrument. Similarly, the F-03A reproduced trumpets with a warm and burnished glow without the shrill edge that can mar the listening experience. Yet the Esoteric didn’t rob trumpet of its vibrant upper-midrange energy, soften its texture, or make it sound like a flugelhorn. All the life and energy were there without the steely glaze—a wonderful presentation.
The F-03A’s Class A liquidity was also on full display with vocals. The new album from The Manhattan Transfer (their first in ten years) features an innovative reimagining of Us3’s “Cantalooop (Flip Fantasia),” which is itself a sampled reworking of Herbie Hancock’s classic tune “Cantaloupe Island.” The dense texture and rich tapestry of The Manhattan Transfer’s amazing vocal harmonies were beautifully served by the F-03A’s liquidity on one hand, and by its resolution and transparency on the other. The voices blended beautifully without congealing; I could pick out the individual parts from the whole yet the dense, multi-hued harmonies were of-a-piece. The vocals on this album are spectacularly recorded (the MQA Studio version on Tidal is stunning), but a very different kind of spectacular than, say, Dean Martin utterly natural and human voice on the 45rpm LP reissue of Dream with Dean.
The F-03A’s rendering of space was superb, not just in width and depth but importantly in the precise placement of images within the soundstage. Notably, instruments were presented as individual objects spatially and texturally, making it easy to clearly hear individual parts within the whole. That’s one quality that many very expensive amplifiers do well; to hear it to this degree from an integrated amplifier was surprising and rewarding.
The F-03A’s moving-coil setting provided plenty of gain for the Sumiko Blue Point No.2 cartridge’s high 2.5mV. The phonostage was dead quiet even on the higher-gain moving-coil setting, delivering black backgrounds and good resolution of very low-level detail. I didn’t hear quite the midrange liquidity and treble smoothness through the phonostage that I do when using the Berkeley Alpha Reference DAC MQA. I attribute that difference to the Sumiko Blue Point No.2 cartridge, not to the Esoteric. Although the Blue Point No.2 is a good cartridge for the price, I suspect that the F-03A will be partnered with higher-quality cartridges. Nonetheless, LP playback had that wonderful feeling of openness and life, with bloom and air around instrumental outlines.
If the F-03A’s output power and bottom-end dynamics aren’t quite enough for you, consider doing what I did: add a JL Audio Fathom f113v2 (or f112v2) subwoofer. Although I evaluated the F-03A without the JL sub for this review, adding the f113v2 for my listening pleasure vaulted the overall system performance into another tier. Forget about any limitations in dynamics, or loudness, or bass impact; the Fathom f113 frees up the Esoteric to do what it does best—deliver delicious Class A sound—while handling the bottom-end duties and bringing 3000W to the party. This combination was the most successful mating of a subwoofer with an amplifier and speakers that I’ve experienced.
From one perspective, the Esoteric F-03A is pricey—thirteen grand for a 30Wpc integrated amplifier is far from budget. Yet to realize the F-03A’s textural beauty, resolution, and liquidity in a powerful Class AB amplifier would push the cost into the stratosphere. The Esoteric delivers the sonic virtues of very expensive amplifiers on a smaller scale, and at a more moderate price. If you have loudspeakers of appropriate sensitivity and realistic expectations about how loudly the system will play, the Esoteric F-03A delivers an immersive musical experience that won’t leave you thinking about your next amplifier upgrade.
Specs & Pricing
Output power: 30Wpc into 8 ohms, 60Wpc into 4 ohms
THD: 0.006% (1kHz, 8 ohms, 30W)
Signal-to-noise ratio: 104dB (IHF-A)
Damping factor: 370
Inputs: Two balanced on XLR jacks, five unbalanced on RCA jacks, external preamplifier inputs (balanced); optional DAC board (OP-DAC1)
Input impedance: 10k ohms (line), 47k ohms (mm phono), 100 ohms (mc phono), 47k ohms (external preamp in)
Outputs: Dual pairs of binding posts with speaker A/B switching; preamp-out jacks (balanced and unbalanced)
Tone controls: +/–12dB at 63Hz, 630Hz, 14kHz in 0.5dB steps
Dimensions: 17.6″ x 7.6″ x 18.5″
Weight: 71 lbs.
18 Park Way
Upper Saddle River, NJ 07458
Sources: AVM CS2.2; Berkeley Alpha Reference Series 2 MQA DAC; Berkeley Alpha USB; Aurender W20 music server; Pro-Ject X Persex 6 turntable with Sumiko Blue Point No.2 cartridge
Speaker cables: Kimber 4TC, Wireworld Mini Eclipse 7
Interconnects: Wireworld Eclipse 7
Digital interconnects: Audience Au24 USB, AudioQuest Wild
AC Power: Shunyata Denali, Shunyata Sigma AC cords
Room treatment: ASC 16″ Full-Round Tube Traps, Stillpoints Aperture Panels, Acoustic Geometry Pro Room Pack 8
By Robert Harley
My older brother Stephen introduced me to music when I was about 12 years old. Stephen was a prodigious musical talent (he went on to get a degree in Composition) who generously shared his records and passion for music with his little brother.More articles from this editor
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