■ REVIEW

Aurorasound Preda

MARTIN COLLOMS TRIES AN INTERESTING JAPANESE PRE-AMPLIFIER
THAT COMBINES SOLID STATE CIRCUITRY, A TRANSFORMER-COUPLEDVOLUME CONTROL, AND FULL REMOTE CONTROLThe Review System
Audio Research REFERENCE
5 SE, Townshend Allegri
control units; Vitus SIA-025,
Naim NAP300 and Krell
Duo300 power ampliﬁers;
Naim UnitiServe network
server and S/PDIF source;
NAIM NDS Streamer/DAC(555 PS), Chord Hugo DAC,
Linn LP12 (Radikal/Keel),
Naim ARO, Koetsu Urushi
Vermilion, Naim SuperLine/XPS sources; Wilson Audio
Sasha Series-II, Magico S-5,
Quad ESL 63 speakers; Naim
FRAIM racks; Naim Super
Lumina, NAC-A5, Transparent
MM2 and Van Den Hul The
First Ultimate cables.

12Aurorasound is specialist Japanese audio
manufacturer with a good track record forhigh quality design and build. The founderof the company is someone called Shinobu Karaki,a highly experienced and respected electronic
designer who worked for Texas Instruments Japanfor 28 years. He is also an audio enthusiast, andstarted up Aurorasound in 2010. His fundamentallysolid state designs involve some novel approaches,searching for new solutions to both higher
subjective ﬁdelity and greater technical accuracy.
We very much enjoyed listening toAurorasound’s Vida phono pre-amp a couple ofyears ago, publishing a notably positive review
in HIFICRITIC Vol7 No3 (the July-Sept issue in2013), so for this review we’re taking a closer lookat the £8,000 Preda line level pre-ampliﬁer. The
two units don’t match at all cosmetically – they’rediﬀerent sizes and shapes, and unlike the Preda theVida even has a wooden sleeve and external power
supply.
Shinobu Karaki has certainly aimed high with
the Preda. Seeking to maximise the performanceof a theoretically near-lossless stepped transformer
attenuator, he uses solid state electronics to buﬀer

the transformer interface, both from the input
and also to the output sections. The electronics
conveniently provide both balanced and singleended facilities for both input and output, a -16dB
gain range switch partly mutes the level for low
volume listening, and the design includes relaycontrolled absolute phase inversion. A large LED
display shows the volume level, as 54x1dB steps.
Six inputs – two XLR balanced pairs and four
RCA single-ended pairs – are provided, along withbalanced and unbalanced outputs (both of which
may be operated simultaneously). At 10.8kg, thePreda is surprisingly heavy for its size, and is built
from thick aluminium plates bolted together toclose tolerances, ensuring very solid, vibration
resistant construction, measuring 42x9x33cm(WxHxD). It normally sits on turned metal feetwith rubber like polymer anti-scratch inserts, but
I certainly enjoyed the clarity and dynamic uplift
provided by Alto Extremo Fat Boy IIs, here used asa trio. All the front panel functions and more are
duplicated on the neat and solid metal infra-red
remote control, which has a good operating range.
The unit has a usefully high input impedance of56kohm, plus a low 47ohms output impedance.
HIFICRITIC APR | MAY |JUN 2015

REVIEW ■MARTIN COLLOMSSound Quality
The ﬁrst part of this assessment was easy as thiscontrol unit is velvety quiet, with dark backgrounds
from which a clear, highly neutral and very wellfocused sound emerges. The designer’s prime aim wasfor stable, high quality sound over the wide volume
range, and that has been achieved in spades. A slightmechanical clicking was audible as the level control isoperated, but this was considered inconsequential.
Stereo images were very stable and consistent withfrequency, and were also notably sharply deﬁned,
providing ﬁne depth and satisfying lower level
ambience. First impressions were of its impressive
standard of neutrality, though this became mildly
modiﬁed following better acquaintance. Ultimately
it resolved to a tinge of ‘bleaching’ or ‘whiteness’,a very slightly desaturated timbre that was just alittle distanced from the familiar character and tonalbalance of well known musical excerpts. If such athing is possible, the overall sound is perhaps just alittle too neutral in the classic sense.
Nevertheless, with its exceptional clarity andhighly deﬁned focus, the sound inspired considerable
conﬁdence, and also conveyed the impression andsensation of a wide linear bandwidth. Rhythm andtiming was rather better than average, and (amongstothers) it made a good stab at driving our reference
Naim NAP 300 power ampliﬁer. It was found tobe particularly eﬀective with highly complex micro
detailed percussion pieces, such as heard on Jan
Garbarek’s Twelve Moons.
When playing some Steve Reich pieces, thesubtle drumming, complex counterpoint, gamelan
and other percussion instruments were all handledwith consummate ease. Fatigue and distortion
were vanishingly low, and it proved easy as well as
thoroughly entertaining to listen to a wide range ofmaterial for long periods into the late evening, while
the clarity remained present even at lower volumes,
leading to an impressive overall score of 115 marks.

graded, switched-step volume control, chosen toavoid the known (if usually tolerable) deﬁciencies of
the continuous track rotary controls that have beenwith us for close to a century. A stepped control may
be used to connect a ‘ladder’ of discrete resistors,
but these may also have some sound quality losses,
together with changes in operating bandwidthand matching over their range. Alternatively thesteps can be a succession of taps on a high quality
audio transformer – some 54 steps are used here – amethod that confers very low noise and distortion
and also preserves signal power through better input/output matching.
Very good as the best transformer-coupledvolume controls can be, when operating throughout
the wider control range that’s required in practice,impedance matching requirements at both theinput and the output will also be changing. At low
frequencies this can aﬀect distortion. In addition theoutput impedance will also vary over the range used,
and this can aﬀect the phase and frequency response
at high frequencies. Aurorasound’s ampliﬁers buﬀer
the transformer-attenuator, allowing it to operate
under optimally terminated conditions. The build
quality here is true dual mono, even for the power
supplies, and selected gold-contact Pickering reed
relays (from the UK, and hermitically sealed in glass)promise a long, stable operating life, and are used
here, both for input and volume selection duty.
A proprietary Aurorasound core ampliﬁer module
is widely used in this pre-ampliﬁer. Indeed, the Preda
uses no fewer than six of this discrete-component
design, which has a wide, low distortion bandwidth.
Power supplies are built back-to-back in order toreduce noise leakage into the audio circuits. Inaddition, instrumentation grade op-amps are used
for the balanced inputs to condition these signals
prior to connection to the main signal path. The
build quality is ﬁrst class throughout.

AUDIO EXCELLENCE

Manufacturer’s Data
Inputs
6x Line level: 4x single-ended
RCA-phono;
2x balanced XLR____________________________
Outputs
2:1x single-ended
RCA-phono;
1x balanced XLR____________________________
Line Gain
3x (10dB)____________________________
Frequency Response
5Hz – 100kHz for -1.5dB____________________________
THD 0.008% (1kHz, 0.5V output)____________________________
InputImpedance
56kohms____________________________
Output Impedance
47ohms____________________________
DCoﬀsetZero____________________________
Size (WxHxD)
420x90x330mm____________________________
Weight10.8kg____________________________
Price£8,000

Contact:
Pure Sound
www.puresound.info
Tel: 01822 612449

Conclusions
While rather more costly than the matching phono
stage, this control unit sets a still higher standard.
High precision best describes the sound, build andoperation, while the range of balanced and singleended inputs alongside full remote control represents
an all-too-rare combination of virtues. Alongside
its ﬁne ﬂexibility and ergonomics, the technicaland subjective performance alone attains the Audio
Excellence standard, which is the rating we award thishighly precise, neutral and informative control unit.

Technicalities
The key component in this design is the use of a well
HIFICRITIC APR | MAY |JUN 201513