Priority to hearing is the motto of Japanese designer of high-end audiophile equipment SoulNote. Prioritising ‘feel’ and musicality over raw, indisputable but cold figures has always been its guiding principle. Its SoulNote A1 integrated amplifier, which caught our attention, is no exception to this rule and benefits from the years of research and development that SoulNote has devoted to developing systems capable of fully exploiting and expressing the liveliness of a sound source.
This quest for naturalness and clarity in sound reproduction requires specific technological choices. Thus, although the A1 has purely analogue power stages operating in class AB, it has no negative feedback loops.
Similarly, SoulNote has equipped the A1 with a direct-coupled output circuit, meaning there are no capacitors. This avoids any risk of colouration or degradation of the audio signal.
Furthermore, although the A1 only boasts a relatively modest power output of 2 x 80 W into 8 ohms, its power stages are oversized compared to those found in many other amplifiers. They use dual push-pull power transistors from Sanken, 2SC2837Y for NPN and 2SA1186Y for PNP.
A quick look at the technical specifications of these components shows that each transistor is capable of handling currents of up to 10 A at a voltage of 150 V.
The A-1 is therefore capable of handling particularly high currents and thus taming even the most rebellious speakers.
In addition, SoulNote has given the A1 an unusually wide bandwidth. It ranges from 3 Hz to 300 kHz. This is quite a feat, since the vast majority of sound reproduction equipment, especially when it comes to power management, peaks at 100 kHz at best.
The A1 is therefore able to reproduce the harmonics of the most extreme high frequencies with ease, provided you have a source capable of delivering them.
But while managing high currents is one thing, the power supply to the power stages must also be capable of delivering them. This is an area where the series resistance of the filter capacitors plays an essential role. To get around this problem, SoulNote came up with the idea of using two groups of eight capacitors, each wired in parallel, instead of two single large capacitors.
This solution reduces their series resistance by a factor of eight, effectively providing particularly high current peaks.
It should be noted that the primary power source is provided by an imposing 350 VA toroidal transformer, which is also very generously calibrated. Another important point is that the A1’s wiring is also very carefully designed.
With a signal path reduced to the bare minimum, it is designed to guarantee the amplifier a particularly low signal-to-noise ratio. Similarly, the number of connectors that the signal has to pass through has also been reduced to the bare minimum.
In terms of connectivity, the A1 again offers the essentials without going overboard. In order to take full advantage of the finesse of higher quality sources, it has a balanced line-level input on an XLR connector, accompanied by three unbalanced inputs on RCA connectors to accommodate the most common sources.
Finally, the A1’s cabinet is also soberly efficient. A significant part of its design was devoted to studying its rigidity and managing unwanted vibrations. The use of decoupling spikes proved indispensable.
One of these, among others, is located directly under the large power transformer in order to dissipate any vibrations it may generate as quickly as possible.
Similarly, the A1’s imposing solid aluminium front panel contributes significantly to the overall rigidity of its cabinet.
INSTALLING THE SOUL NOTE A1
If you touch it, you’ll get hurt, as the manual for this integrated amplifier warns. The A1 rests on three particularly sharp decoupling cones. So be sure to install it on a rigid support, but with counter-spikes. The second precaution to take is to pay attention to the mains phase. Depending on the case, the difference can be significant. The A1 is capable of powering a wide range of speakers. The list of compatible devices is therefore not restrictive.
THE SOUND OF THE SOUL NOTE A1
A1 is an interesting name. Like its British namesake, the Soul Note is a real charmer with an endearing personality. You immediately feel at ease with it. And it is comfortable with many speakers. Coming from Japan and distributed in France by the same expert as its compatriot SPEC, it takes the opposite approach with the same talent.
While SPEC focuses on purity and minerality, Soul Note offers a dense and full-bodied vision of sound reproduction with a superbly measured warmth that never overdoes it.
Its credo is balance, which it handles with the mastery of a tightrope walker. You only have to see the care with which it paints a panorama, the passion with which it builds a melodic gradation. Some would say it is romantic.
We don’t dispute this description, we can understand it, but we might find it somewhat restrictive. For our part, we find him surprisingly realistic and rooted in his time. He knows how to add depth when necessary, but also how to be perfectly subtle when restraint is required. We were amazed by the maturity he displays at this price point.
Whether it’s the structure of the holographic reproduction, the way it creates an impeccable hierarchy in the playback of different melodic lines, or its ability to remain as neutral as possible when it comes to favouring timbres, the A1 remains pragmatic without ostentation, but with a cheerful and assertive character that gives it above-average appeal.
OUR CONCLUSION
This is a very interesting integrated amplifier from Japan. Its build quality and original design make it a very mature product. The youngest member of a range that is confidently rising to the top, the A1 is an amplifier that can be easily paired with sources and speakers from various sources.
Versatile, it will adapt very easily to deliver the essence of the music. Hyper-musical and always very comfortable, the A1 is a delight at every moment.
Author: Estève Fabry and Laurent Thorin
TECHNICAL SHEET: SOULNOTE A1
- Origin: Japan
- Price: €3,600
- Dimensions: 430 x 109 x 418 mm
- Weight: 10 kg
- Power output: 2 x 80 W into 8 ohms, 2 x 120 W into 4 ohms
- Damping factor: >50
- Frequency response: 3 Hz to 300 kHz
- Total harmonic distortion: <0.08%
- Signal-to-noise ratio: 110 dB
