Audio Database

PMA-S1
Commentary

This is a pre-main amplifier that inherits the concept of POA-S1 and achieves a high level balance between sensitivity and strength.

A high-current amplifier UHC MOS is used for the amplifier.
The current supply capability of the UHC MOS is improved to be equal to or higher than that of the bipolar transistor, and the UHC MOS also has the sound quality advantage of the MOS FET.
In addition, the cascode bootstrap method is adopted in order to maximize the capacity of this element. It realizes an ideal load to the power amplifier stage and realizes a simple and straight configuration. The source resistance, which has been a cause of contamination of sound quality, is also eliminated by taking advantage of the stability of UHC MOS.

The BTL circuit provides high output power at low power supply voltage, making it possible to use superior acoustic devices.
In addition, the ground circuit and the output current of the speaker are completely separated to achieve higher sound quality.

The chassis is made of non-magnetic sand castings that have excellent vibration damping characteristics, are resistant to magnetostriction, and can be processed with high precision. Moreover, the chassis and radiator are integrated to achieve high rigidity and non-resonance.
In addition, the core of the transformer and sintered alloy insulator are also fixed directly to the sand-cast chassis, pursuing the limit of the vibration isolation structure.

It is equipped with a newly developed NEW inverted Σ balance circuit that supports both balanced input and normal input. It eliminates the need for separate conversion circuits at the input stage and voltage amplification stage. It is a balanced direct design that allows direct input to a balanced power amplifier of BTL configuration.

The equalizer amplifier uses a two stage dedicated constant-voltage power supply.
When the Phono input is not used, the circuit and power supply can be completely shut off by turning the EQ Power switch OFF. This eliminates the influence on the sound quality of line inputs such as CDs.

There are no pre-out, main-in, tone control, filters, loudness, muting, or headphone jacks to keep the signal path simple and straight.

Model Rating
Type Pre-main amplifier
Power Amplifier Unit
Rated output 100W + 100W (4 Ω, 1 kHz)
50W + 50W (8 Ω, 20 Hz to 20 kHz)
Total harmonic distortion factor 0.007% (1 kHz, 25W, 8 Ω)
Output bandwidth 5 Hz ~ 50 kHz (Output 25W, 8 Ω, THD 0.1%)
Output impedance 0.1 Ω or less
Speaker output terminal 4 Ω ~ 16 Ω
Preamplifier Section
Input Sensitivity / Impedance Phono MM : 2.5mV/47k Ω
Line : 150mV/47k Ω
Balanced : 150mV/100k Ω
Maximum allowable input voltage Phono MM:150mV(0.1%)
Rated output Rec Out:150mV/1kHz
Equalizer (RIAA deviation) 20 Hz to 20 kHz ± 0.3 dB
Total harmonic distortion factor 0.002% (1 khz, 5 v)
<General>
Signal-to-noise ratio Phono MM : 91 dB at 5 mV input
Line:108dB
Power supply voltage 100 VAC, 50Hz/60Hz
Power consumption 230W
External dimensions Width 434x Height 155x Depth 493 mm
Weight 25.5kg