331 Integrated Amplifier

Description

Philosophy
Most integrated amplifiers combine the functions of volume control, source selection and amplification in single multi-function circuit. Not so the soulution 331 Integrated amplifier. It takes the uncompromising route of separate circuits, combining a dedicated preamplifier, a dedicated power amplifier, a first class phono stage and an exquisite D/A-converter in one housing. It is a real soulution product – truly a great amplifier.

New power supply
Four new cutting-edge switched-mode power supplies modules deliver 1,200 VA of continuous power for the power amplifier section with a peak power capability of up to 4’200 VA for more than 5 seconds. They feature high performance filtering at the input and output, and high speed soulution voltage regulators to deliver considerably more stable power than any conventional, transformer-based technology.

Power amplifier
The amplification circuit of the 331 is based on the technology used in our Series 5 amplifiers. Current amplification is done in three stages, each with a narrow, almost linear operating range. The high Class A operation supplemented by more than 160,000 µF of storage capacitance results in a nearly infinite impulse response.

Preamplifier and volume control
Relay-switched high precision metal foil resistors form an 80 step (1 dB) volume control. To avoid unpleasant clicking noises or harmful voltage peaks during volume adjustments, the 331 is provided with a second volume control path which is active only during volume adjustments. This secondary, IC based volume control alters the volume without any click or pops. Once the new volume is set, the 331 will revert to the sonically superior path with its high-precision metal foil resistors. The frequency bandwidth of the preamplifier section could be extended to more than 2MHz (-3dB), which does significantly reduce the phase shift in the audio band.

Phono stage (optional)
A two stage, active/passive, design equalizes the input signal according to the RIAA specifications. Tight tolerance, high quality passive components in the RIAA networks ensure highest precision of the required time-constants. Three wide bandwidth, low noise amplifier stages provide 60dB gain with minimal deviations to the ideal frequency and phase response of the system. The adjustable termination impedance (via the remote or front panel controls) allows to perfectly align the phono stage to your MC phono cartridge.

DAC (optional)
With its 4 digital inputs (SPDIF, AES/EBU, Network, USB) provides connectivity to a wide selection of digital sources. A powerful DSP converts all incoming digital music signals to the DXD format, performs the zeroPhase processing and the LEEDH volume control. One PCM1792 in mono configuration per channel takes care of the digital to analog conversion of the music signals. The internal digital filtering of the chip is bypassed for optimal results. The passive reconstruction filter sports custom made high precision components ensuring stable filter characteristics, prerequisite for a perfect compensation with the zeroPhase technology.

Operation
The 331 integrated amplifier is operated via its three front panel buttons and rotary control. Multi-functional, these allow optimisation of the entire audio system, and an ideal set-up of the individual components. All operating modes are indicated on the clear display.