Shinobu Karaki, a 65-year-old electronics designer, is the founder and chief designer of Japan's Aurorasound. A music lover first, an audiophile second, and an aspiring jazz and…
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Audiophiles are often misunderstood as mere hobbyists; in fact they hold a profound reverence for sound. Japanese jazz kissas, where vintage vinyl, turntables, tube amplifiers, and horn speakers have drawn audiences since the 1950s, exemplify this passion. Western audiophiles share a similar fervor, though our pursuit of sonic perfection often manifests in a more discreet, almost monastic, lifestyle (footnote 1).
Listening
The HFSA-01 played well with all kinds of music, its forward-motion pacing, exacting clarity, and exceptional coherency making it a fine dance partner regardless of the tune.
For old-world stereo, I played Guem Et Zaka Percussion (1978, Le Chante De Monde LDX 74674), jazz trumpeter Kenny Dorham's Una Mas (1966, Blue Note Liberty BST 84127), Terje Rypdal, Miroslav Vitous, Jack DeJohnette (1978, ECM 1125), and Antal Dorati conducting the London Symphony Orchestra performing The Firebird (1997, Mercury SR90226). Forq's Big Party (GroundUP) brought 2024 stereo action…
Sidebar 1: Specifications
Description: Hybrid (tube output/solid state input) push-pull integrated amplifier outputting 14Wpc into 8 ohms (11.46dBW). Tube complement: 4 EL84. Inputs: 3 pairs single-ended (RCA). Outputs: Two pairs loudspeaker output terminals with 4/8 ohm taps; ¼" headphone. Frequency response: 10Hz-40kHz, –3dB. THD+N: 0.08% at 1kHz, 2W, A-weighted. Signal/noise ratio: 93dB, Line in, line out. Damping factor: 4. Gain: Line input to speaker output, 29dB. Phono input to speaker 69dB. Input impedance: 47k ohms, line or phono in. Max. power consumption: 150W. Phono: gain (MM…
Sidebar 2: Associated Equipment
Analog sources: Thorens TD 124 turntable with Korf TA-SF9R tonearm, Korf HS-A02 Ceramic Headshell, Kuzma CAR-30 MC cartridge, Rega Nd3 MM.
Digital sources: HoloAudio May DAC, Sonore opticalRendu, Roon Nucleus+, Small Green Computer power supply, TRENDnet switch, Apple iPad mini.
Preamplifiers: Tavish Audio Design Adagio, Manley Chinook (phono); Auditorium 23 and Bob's Devices step-up transformers; Rogue Audio RP-7.
Power amplifier: Rogue Audio Stereo 100.
Integrated amplifiers: PrimaLuna EVO 300 Hybrid, Riviera Labs Levante.
Loudspeakers…
Sidebar 3: Measurements
The Aurorasound HFSA-01 was shipped to me with the four Sovtek EL84/6BQ5 tubes installed. I removed the small lid on top of the chassis to make sure the tubes were correctly seated, then performed a complete set of tests with my Audio Precision SYS2722 system. To check whether some of the results were due to aging or to out-of-spec tubes, I installed a matched set of new TubeDepot JJ EL84s then repeated the testing.
Looking first at the line inputs, the HFSA-01 preserved polarity from both the 4 ohm and 8 ohm output transformer taps and from the headphone…
More Measurements
To examine the phono input's performance, I connected a wire from the grounding terminal on the amplifier's rear panel to the analyzer's chassis ground to minimize noise. To avoid overdriving the tubed output stage, I mostly did this testing by looking at the headphone output. (The manual says that inserting a plug into the headphone jack turns off the speaker outputs, but I found that rather than muting them completely, it reduced their level by 44dB.)
What if there was a character in Stanley Kubrick's classic movie 2001: A Space Odyssey who was an audiophile? Aboard the Discovery One interplanetary space ship, what would his system look like? He'd probably have a pair of ultramodern speakers that could pluck sound out of the ether. He'd control the system with something like a present-day smartphone or tablet, commanding the HAL 9000 computer to play his favorite songs. The speakers would stand unobtrusively in a white room with 1970s modern-minimalist furniture, no rack of components to drive them, no wires connecting them, no shelves of…
The 6.5" mid/bass driver includes a "Tuned Mass Damping" rounded surround and a "Neutral Inductance Circuit": a ring between the magnet and voice coil to keep the magnetism at the voice coil uniform throughout its range of movement. Mid/bass and woofer cones are made of Focal's "W" material, a sandwich of foam between two glass-fiber layers, designed to provide the desirable combination of rigidity and damping so that the cone vibrations are "pistonic," the whole cone vibrating at once, responding directly to the electrical signal.
The two 6.5" long-throw woofers on each side of…
Getting set for some music
On a rainy day in September, the speakers arrived on a large pallet, one box each plus a box for accessories (remote control, documentation, spikes, and so on). The speakers weigh 141lb each; buyers will be grateful that they're delivered on wheels and with a sturdy plywood ramp. Just open the box, remove some packing material, slide the ramp under the wheels, tip the speaker upright, and roll it out. The wheels are useful not just for uncrating but also for positioning. Once that has been accomplished, the screw-in spikes or feet can be adjusted with…
B>Sidebar 1: On The Inside
Occupying nearly the full height of the cabinet interior is the huge linear PSU, the DSP section, and the class-AB amplifiers (their heatsinks facing outward) that power its four bass units, midrange driver, and tweeter. Lowering the cabinet's center of gravity is a 700VA toroidal transformer (bottom left) feeding all the linear PSUs across the two main PCBs. A small switch-mode PSU under the black…