Aurorasound HFSA-01 integrated amplifier

AurorasoundIs globally known and recognized for the quality of its Phono preamplifiers. Lesser-known information, but worth mentioning, Mr. Karaki has been offering amplifiers for several years and preamplifiers very high-quality high-fidelity. TheAurorasound HFSA-01 is the first integrated from the manufacturer to be offered outside of Japan.

AURORASOUND HFSA-01: Façade

This amplifier has nothing in common. The size of the case is atypical and its look is part of the brand's DNA, even though it does not resemble any other element offered by it. However, the "modern" vintage design of theAurorasound Vida.

The brushed natural aluminum front panel is adorned with Mahogany side cheeks, which enhance the retro look. There are four potentiometers that respectively control the tones (bass and treble), the volume, and the source selection.

On the panel below, we have access to the power button backlit in red, a Tone Off switch, and a mono switch, and a headphone output in Jack 6.35mm stereo.

AURORASOUND HFSA-01: Connections

LHFSA-01 integrated amplifier Propose 3 high-level line inputs, in RCA format. In addition, there is an excellent phono input. Its impedance of 47k Ohms combined with a gain of 40 dB makes it suitable for MM cellsHaving a minimum output level of 4mV. But the addition of a transformer"Step Up" will allow the connection of a low-level MC cell. 

The speaker outputs accept speakers with an impedance of 4Ω to 8Ω. It is possible to connect banana plugs or spade connectors.

The power cable can be advantageously replaced with a higher quality product via the IEC socket.

AURORASOUND HFSA-01: Technology

L’Aurorasound HFSA-01 is a integrated amplifier hybrid which uses the advantages of audio tubes and semiconductors. The power stage is designed from a push-pull of EL84. This vacuum tube is a pentode equivalent to the 6BQ5. In this push-pull (ultra-linear) configuration, a power of 14W + 14W at 8 Ohms is obtained with extremely low distortion and excellent frequency response (10-40,000 Hz).

The tubes are driven by a famous amplifier operational of Texas Instruments OPA604A. Aurorasound developed especially for this amplifier an optimum phase inversion circuit with this OPA604A, which allows driving the push-pull operation in the most ideal way possible.

There is a large power transformer, and of course two output transformers. They are custom designed by Aurorasound and manufactured by a Japanese company. They are paired with carefully selected high-quality capacitors and resistors.

L’power supply is completely isolated between the tube and the semiconductor to completely eliminate interference, regardless of the volume level and frequency range. The rectifier bridge is designed with Rohm silicon carbide diodes with very low noise.

The tone control section uses a CR type to achieve richer bass and more present treble, to meet the sound preferences of users. This can be interesting on some speakersSmall in size.

The phono stage is designed around a Linear Technology semiconductor to achieve an excellent signal-to-noise ratio with an NF-type circuit configuration.

It also has a headphone output that is directly coupled between the preamp and the power drivers.

L’amplifier Aurorasound HFSA-01 is entirely handmade in Yokohama, Japan. Each amplifier undergoes precise measurement and listening tests before shipment.

AURORASOUND HFSA-01: PHONO EASY COMPENSATOR:

L’amplifier AURORASOUND HFSA-O1 is delivered with a screen-printed plate that is placed in place of the bass and treble tone knobs.

The tone controls of this amp are transformed into equalization curve settings for thephono input. This allows for proper playback of pre-RIAA vinyl records. It offers adjustment of different equalization curves (RIAA, DECCA, Columbia, AES, NAB, 78SP) on thephono input. This hidden function in the absence of a plate is a very useful tool for enthusiasts of vinyle.

AURORASOUND HFSA-01: Test and listening 

To begin with, do not rely on the announced power! Once plugged in, theintegrated amplifier Aurorasound HFSA-01 surprises precisely by its ability to drive the speakers with disconcerting ease.

From the beginning, in order to push it to its limits, we paired it with a pair ofspeakers totally oversized for him, at least we thought so (3-way column, 4 Ohms/ 88 dB, > 9000 euros). We were completely captivated by the quality of the reproduction and the ease demonstrated by the HFSA-01.

Clearly, the midrange is sublime in its transparency and neutrality. It offers an uncommon realism on the vocals. The reproduction is teeming with details and nuances. The top of the spectrum is also particularly successful and perfectly integrated with the rest of the spectrum. The treble extends very high with surprising softness and finesse. This register is very close to what you find on some very high-end tube electronics. What can be said about the bass!? It is superb in its articulation and precision while remaining very organic. The dynamics are surprising and even unexpected given the announced power! The whole enjoys a balance and elegance that few electronics currently can claim. You can listen to it for hours without any boredom or fatigue. It breathes into the music that extra soul which is often lacking in many high-end electronics. It is also noticeable that it seems to exhibit a certain "cheerfulness" that gives full meaning to the much sought-after "musicality." This integrated amplifier is among the best I have had the opportunity to listen to to date.

La Phono Easy Compensator plate is not a standard feature and you can choose to include it or not if you prefer the clean look of the front of the HFSA-01.

However, it should be mentioned that equalization curves play a crucial role in the playback process of a vinyl record engraved before 1958. The proposed curves essentially reverse the RIAA equalization curve applied to records. The Recording Industry Association of America (RIAA) established this standard curve in 1954, which has been used in most records produced since the late fifties. However, before the RIAA standardization, record companies used various equalization curves, resulting in the use of more than 100 different curves. Serious collectors of 78 rpm and mono records often prefer phono stages that offer selectable equalization curves to accommodate these different standards.

It is important to note that selectable equalization curves remain the exception rather than the rule in the Phono stages of quality, and unique nowadays on a integrated amplifier. Therefore, the addition of this function in theintegrated amplifier HFSA-01, in its price range, is quite remarkable and greatly appreciated.

This amplifier reconciled me with the EL84 in Hi-Fi use, even though I have always appreciated these tubes for their dynamics and clarity in a guitar amplifier, for example! How is it possible to get so much music out of such a small tube?

We also note an advantage, the retubing of this Aurorasound amplifier will be very economical (around 120 euros for 4 matched tubes). It is known to have only one competitor, and it is also Japanese, but the latter is certainly less neutral. Thehybrid integrated amplifier HFSA-01 is certainly the best value for money/music that one can acquire!

Congratulations again Mr. Shinobu Karaki!

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