soulution 755 phono preamplifier

1.128.000 

The subtle signals of the extremely low output moving coil cartridges pose real challenges to the analogue circuitry in order to achieve low noise, low distortion, high channel separation and maximum linearity while providing more than 80 dB gain – equivalent to raising the signal level by 10,000 – yet must exhibit level and phase accurate behaviour while adhering strictly to RIAA-IEC equalisation standards.

The 755 Phono preamplifier easily complies with this challenging specification: Now analogue records really can sound their best. Their most captivating ever.

Layout

Unbalanced circuit design ensures having as few components in the signal path as possible. Dual-mono layout with discrete left and right channels maximise audio purity and virtually eliminates crosstalk. Input selection (including the ground connection) is done by high-grade relay. And input buffering ensures the 755 presents a benign load to the cartridges. For all three inputs (2 × MC, 1 × MM) the gain factor and the terminating impedance are freely selectable. To suppress rumble from warped records there is an IEC subsonic filter (< 20 Hz) which will protect loudspeakers against hazardous cone excursions. Mono operation is selectable as well.

Volume control

The analog, passive volume control uses high-precision, low-noise metal foil resistors, and controls both volume and balance. To block switching peaks during volume changes which may be hazardous to power amplifiers a second volume control with PGA (Programmable Gain Amplifier) is used. Active only when the volume is changed, it is similar to a potentiometer and enables the volume to be adjusted in smooth steps without clicks. As soon as the new desired level has been selected, the unit returns control to the precision resistors.

In case the 755 Phono preamplifier is not connected directly to the power amplifier but to a line preamplifier, the volume control may be switched out of the signal path completely.

Phono module (equaliser)

The challenges to the ideal phono amplifier are immense and represent the «pièce de réstistance» for every designer of high-class audio amplifiers. With a gain of up to 80 dB (which equals an amplification factor of 10,000) the amplifier is expected to show a level and phase true behaviour, i.e. an ultra wideband quality (internal amplifier bandwidth 1  MHz/–  3 dB). At the same time it is to compensate the equalisation curve in accordance with RIAA-IEC standards. This can only be realised by means of a multi-stage amplifier concept using super-grade components.

Output stage

No deletions at the source of the music reproduction are key, therefore a top grade output stage is mandatory. We use the identical circuit as for the 725 preamplifier. The wideband output stage is based on an optimised circuitry with special power transistors which are further linearized by an analogue computing network and has a bandwidth of 40 MHz (– 3 dB). With such speed of response all musical details are reproduced true to life creating a three-dimensional, spatial sound to bring real listening pleasure.

Power supply

Key to any good sounding audio source component is a stable, noise-free power supply – especially for the audio stages. The 755 is equipped with two dedicated power supplies: one for the audio stages and one for the digital circuits. For powering the audio stages an innovative, amplifier-like circuit design is used, providing an extremely stable supply voltage. With more than 500,000 µFarad of storage capacitance it provides almost unlimited impulse current for the analog circuits. Bus bars supply this power throughout the 755 phono preamplifier without any losses. A unique concept in the audio world!

Operation

The 755 phono preamplifier is operated from front-panel buttons and a rotary control. Further functions can be used to optimise and match an entire audio system around different components.

Mains 220 – 240 V (50 – 60 Hz)
100 – 120 V (50 – 60 Hz)
Power consumption < 0.5 W standby
60 W device in operation
Inputs 2 × MC unbalanced (RCA)
1 × MM unbalanced (RCA)
Input impedance MC: 10 Ω – 1000 Ω
MM: 47 Ω – 47 kΩ and 0 – 750 pF
Outputs 1 × balanced (XLR)
1 × unbalanced (RCA)
Frequency response (– 3 dB) 0 – 1 MHz
THD + N < 0.002% (20 Hz – 20 kHz)
Signal-to-noise ratio 100 dB
Channel separation 60 dB @ 1 kHz
Gain (max) MC:

MM:

+ 78 dB balanced
+ 72 dB unbalanced
+ 66 dB balanced
+ 60 dB unbalanced
Volume control range 0 to – 79 dB in 1 dB steps
Output impedance 2 Ω balanced (XLR)
2 Ω unbalanced (RCA)
Output voltage 16 VRMS balanced (XLR)
8 VRMS unbalanced (RCA)
Output current max 1 A (limited)
Dimensions 480 × 167 × 450 mm
(W × H × D)
Weight approx. 30 kg
LINK (remote turn-on) 12 V control signal

Philosophy

A CD or SACD player brings both digital and analogue domains into an audio system. For the very highest quality sound every part of the player is critical. A high-quality D/A converter alone is no longer enough. The 746 unites a top quality optical drive, a super-precise master clock generator, an intelligent digital signal processor with over­sampling, and analogue output stages of the utmost quality. Together they ensure nothing in the music is lost on its way from disc to output connection.

Design

As with its Series 7 sibling the 560 D/A-Converter is packed with cutting-edge tech­nology with one objective – the love of music. The parallels include a consistent dual mono design in the output stages and separate power supplies for digital elec­tronics and the analogue stages. The 560 D/A-Converter adds a digital volume control that allows direct connec­tion to a power amplifier.

D/A conversion

Burr-Brown devices perform D/A conversion only. Their internal upsampling and filter stages are not used. The output currents are converted to voltage and then filtered. With an internal bandwidth of 40 MHz, this current/voltage conversion stage allows best signal-to-noise performance and maximum dynamics in the analogue domain.

Brand

soulution

Kategorie: , Štítek: