Soulnote A-0 Integrated Amplifier
Fully Non-Feedback Discrete Circuit
The SA1.0’s non-feedback discrete amplifier circuit has been thoroughly redesigned. By improving the driving power of the voltage amplification stage and simultaneously reducing the input load of the final stage, we’ve achieved improved driving power across the entire frequency range while achieving a wider range.
Dual Balanced Inputs
The A-0 features two balanced inputs. The balanced input signal is selected as is, without unbalanced conversion, and then adjusted for volume and transmitted to the differential input of the voltage amplification stage.
Contactless Wiring
Following the non-contact signal system adopted in the higher-end A-1 model, the connection from the balanced input to the speaker output has been eliminated, resulting in a non-contact system.
Gain Selector Switch
The gain selector switch has been moved to the front panel. The volume circuit has also been redesigned to minimize changes in sound quality caused by gain selection, dramatically improving the dynamics of the sound even at low volumes. Selecting low gain when listening at low volumes allows for more precise volume adjustment.
Output Selector Switch:
A new switch has been added to select between speaker output and pre-out output. Easily switch between two systems: speakers connected to the A-0 and a power amp and speakers connected to the pre-out.
Super-Powerful Pre-Out & Headphone Output
Both the pre-out and headphones are output directly from the same non-feedback discrete power amplifier that drives the speaker output. Since it can also drive speakers, it can be considered an ultra-powerful preamp/headphone driver.
High-Quality Output Stage
By deliberately limiting the maximum output to 10W, sufficient for general home use,
it has become possible to use transistors (2SA1930/2SC5171) in the final stage, which offer excellent frequency response, linearity, and complement accuracy.
Using these in a single push-pull configuration achieves transparent, dynamic sound quality.
This can truly be described as a “power amplifier” method that drives speakers with pre-out quality.
The multi-heat sink system
A-0 has twice the thermal capacity of the heat sink as the sa1.0. In addition, by separating the heat sinks for the final stage and the driver stage and
configuring temperature compensation circuits tailored to each stage, the stability of the idling current has been significantly improved,
resulting in a sound that is both dynamic and deep.
Ideal Construction & Pattern Layout
The adoption of a full-size chassis has achieved the ideal construction refined in the A-1.
The current return loop from the transformer to the rectifier circuit has been minimized, while the power supply circuit and amplifier circuit have been ideally positioned in the shortest possible distance.
Furthermore, the ground pattern has been star-wired, which has resulted in a dramatic improvement in the audible S/N ratio and the realism of the sound.
Direct Mechanical Earth Construction
By installing spike pins directly under the transformer, harmful transformer vibrations are released directly outside the chassis. In addition, by supporting the product’s legs at three points with spike pins, muddy sound caused by chassis damping is eliminated,
resulting in a lively, soulful sound.