Series 7

Complete silence inside. No alternating current. No transformers. No stray fields. Perfect conditions for the multi-stage, low noise amplifier to perform at its absolute best. The height of achievement in phono amplification. An audiophile’s dream that until now had simply not been realized.

Now analogue records really can sound their best. Their most captivating ever.

Highlights

Philosophy
Building the ideal phono amplifier is the ultimate challenge for audio designers. It must work with the extremely low signal levels of moving coil (MC) cartridges while achieving low noise, low distortion, high channel separation and maximum linearity. It must provide up to 80dB 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.

Design
The soulution 750 (three MC inputs) and 751 (two MC inputs, one MM input) have risen to this design challenge supremely well. Based on an advanced design around an ultra wide band (1 MHz/– 3 dB) multi-stage amplifier, both are built with the very highest quality components.

For all inputs the gain factor and the terminating impedance are freely selectable. The working bandwidth may also be chosen from either Low (200 KHz) or High (1 MHz) to within – 3 dB. To suppress rumble from warped records there is an IEC subsonic filter (< 20 Hz) which will protect loudspeakers against hazardous cone excursions. On the 750/751 there is also a key to select mono operation.

A front panel level control allows sound level balancing across the three inputs.

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
The output stage of the 750/751 is optimized for velocity, precision and current capability thus ensuring all the musical detail is passed to attached pre/amplifiers. Furthermore it is stable with interconnects of any length and has a bandwidth that extends to 40 MHz (– 3 dB), ensuring every musical detail is reproduced true to life. The result is a three-dimensional, spatial sound of uncanny accuracy and detail.

Power supply
Above all a phono amplifier needs an electrically quiet environment. To eliminate any chance of interference from the power supply, the 750/751 is powered entirely by either pure DC from an associated 720/721 preamplifier or from a dedicated soulution external supply. This removes any AC mains voltages or stray magnetic fields.

Specifications

Mains	externally via 750 PSU or 725
Power consumption	< 0.5 W standby 20 W device in operation
Inputs	750: 3 × MC (RCA) 751: 2 × MC, 1 × MM (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	< 0.006% (20 Hz – 20 kHz)
Signal-to-noise ratio	100 dB
Channel separation	60 dB @ 1 kHz
Gain (max)	MC: MM:	+ 66 dB balanced + 60 dB unbalanced + 54 dB balanced + 48 dB unbalanced
Volume control range	0 to – 15 dB in 3 dB steps
Output impedance	10 Ω unbalanced (XLR) 10 Ω unbalanced (RCA)
Output voltage	7 VRMS balanced (XLR) 3.5 VRMS unbalanced (RCA)
Output current max	0.2 A (limited)
Dimensions	480 × 117 × 450 mm (W × H × D)
Weight	approx. 17 kg
LINK (remote turn-on)	12 V control signal

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.

Highlights

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.

Specifications

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

No deletions at the source are mandatory. This holds even more true for the playback of high resolution files as it did for CDs and SACDs anyhow. No amplifier or loud­speaker can ever make good for what has been lost at the source. The quality of the recording and the signal supplier are of fundamental importance in high fidelity.

The 760 D/A-Converter does excell at exactly this task. It captures all digital music data and transports it in the analog domain. No deletions, no additions!

Highlights

Design
In many areas the 760 D/A-Converter is based on the same proven technical solutions used in the 745 SACD-Player. It also embodies the same principles in its design: top grade digital inter­faces for optimal reception of the music data, a super-precise master clock generator to avoid jitter, intelligent digital signal processing with over­sampling and Zero Phase technology, analogue output stages of top end pre­amplifier quality and a husky power supply.

The 760 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 760 D/A-Converter adds a digital volume control that allows direct connec­tion to a power amplifier.

Oversampling
A powerful SHARC DSP performs the 8 x over­sampling to 24 bit/352.8 kHz or 24 bit/384kHz, depending on the digital input signal with the utmost precision. We believe precision of inter­polation is more impor­tant than high clock rates. Our players and D/A converters use an algorithm from the highly regarded Anagram Technologies followed by Burr Brown D/A converters in a digital symmetric configuration. As we consider the PCM conversion technology as superior, the DSD signals get converted before its final D/A conversion.

zeroφtech
The 760 D/A-Converter is equipped with soulution’s innovative Zero-Phase-Technology. Smallest timing errors provoked by the analog low pass filter of the D/A converter get eliminated. Every D/A converter requires an analog low pass filter in its output in order to suppress high frequency noise and aliasing signals. The 760’s 3^rd order bessel filter, with a cut-off frequency of 120 kHz, does show a phase shift of up to 15° in the audio band. Due to the Zero-Phase-Technology the phase error of the analog music signal remains below 1°, 20 Hz – 100 kHz! The Zero-Phase-Technology brings you even closer to the beauty of the source material! The music gets even more realistic and 3-dimensional with a lot of “air” around instruments and voices. As close to the source as possible! No detail gets lost.

Clock
Utmost precision of the clock signal is a must have for a top class D/A-Conversion. Lowest phase-noise behaviour is by far more important than long term frequency stability. Together with experts for highend oscillators we did develop a TCXO which is optimized for this application. It does not run on its first harmonic but on its 3^rd overtone. The clock modules work at frequencies around 100MHz, this re-quires extremely fast amplifier stages within the oscillator loop but allows achieving best results regarding phase-noise. Even the best OCXOs or rubidium based oscillators are not able to outperform these specifications. The 760 DAC does have a spate oscillator module for signals based on 44.1 kHz and signals based on 48 kHz. With the synchronisation to an external clock signal the performance of these oscillator modules would be deteriorated. Therefore the 760 does not provide a clock-input. However, external components can be synchronised to the 760 D/A-converters high quality clock signal through its clock-output.

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 80 MHz, this current/voltage conversion stage allows best signal-to-noise performance and maximum dynamics in the analogue domain.

Output stage
The wideband output stage of the 760 D/A-Converter, which is based on an optimised circuitry with special power transistors which are further linearized by an analogue computing network, 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 760 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 760 D/A converter without any losses. A unique concept in the audio world!

Operation
The 760 D/A converter 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.

Specifications

Mains	220 – 240 V (50 – 60 Hz) 100 – 120 V (50 – 60 Hz)
Power consumption	< 0.5 W standby 60 W device in operation
Analog outputs	1 × balanced (XLR) 1 × unbalanced (RCA)
Frequency response	0 – 200 kHz (DXD)
THD + N	< 0.0005% (20 Hz – 20 kHz)
Signal-to-noise ratio	> 140 dB
Channel separation	> 130 dB
Output impedance	2 Ω balanced (XLR) 2 Ω unbalanced (RCA)
Output voltage	4 VRMS balanced (XLR) 2 VRMS unbalanced (RCA)
Output current max	1 A (limited by protection circuit)
Volume control range	0 to – 79 dB in 1 dB steps
Digital inputs	AES/EBU, SPDIF-RCA, Optical, USB, Network
Digital outputs	AES/EBU, SPDIF-RCA, Clock-BNC
Digitale formats	WAV, AIFF, FLAC, ALAC, DSF, DFF, DXD, MP3, AAC
Bit dept/sampling rage (max)	AES/EBU: SPDIF: Optical: USB: Network:	24 bit/192 kHz 24 bit/192 kHz 24 bit/ 96 kHz 24 bit/384 kHz, 1 bit/5.64 MHz 24 bit/384 kHz, 1 bit/5.64 MHz
Dimensions	480 × 167 × 450 mm (W × H × D)
Weight	approx. 30 kg
LINK (remote turn-on)	12 V control signal
USB driver	v1.22c for Win7 v1.611 for Win7 v2.26 for Win10