The Opus   'zaha'

 
 
 
 
 
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Overview

The OPUS is the direct result of an intense 35 years fascination with music recording and reproduction to perfect the most transparent, reference calibre “monitoring” preamplifier to complement both the finest domestic audio playback & professional recording systems in the world. Using technology borrowed from Aerospace and Formula 1, the design also reflects the extraordinary advances that made over the last 15 years in modelling and simulation software.

In the early 2000’s, Kostas Metaxas underwent extensive training to become one of the first designers who could conceive, model and prototype an entire amplifier on a component by component basis in 3D.

 

The PCB software he uses not only lays out the boards, but also allows schematic based simulations which can test [or verify] the PCB’s signal integrity displaying Reflection and Crosstalk Analysis.

Not content with a strict engineering approach, Metaxas started working on creating the ultimate library of test recordings using three “metaxas-modified” portable Swiss Stellavox SM8 [10” reels @ 15ips] Analogue tape machines with Neumann [M150, TLM50 and TLM170] and B&K [4135 and 4133] microphones to record and film over 300 live acoustic concerts.

Many of these recordings are also used today as references by many of our esteemed manufacturer colleagues.

To house this cutting-edge technology, a striking “organic” case design was 5-axis CNC machined from a solid block of Aircraft Aluminium [or Copper or Titanium] to shield and mechanically ground the low-level signals.

All switches, attenuators and sockets/plugs [hardware] are of the highest possible quality, many meeting or exceeding military specifications.

This future-proof preamplifier offers the simplest, purest signal path. Additional “Plug-in modules’ allow almost infinite possibilities for the addition of LP phono RIAA equalized playback, microphone preamplification or Digital recording [ADC] and Playback [DAC].
In its basic format it comes with a “Mainframe” and separate AC Mains Isolated Power Supply connected by two aerospace-grade umbilical cords.

Specifications

FREQUENCY RESPONSE: DC - 10MHz (-3dB)
VOLTAGE OUTPUT: 15VRMS per channel into 50 Ohms with no more than 0.05% T.H.D.
SLEW RATE: Greater than 1000V/us small and large signal
T.H.D.: Less than 0.005% 20Hz-20KHz
I.M.D.(S.M.P.T.E.): Less than 0.005%
SIGNAL/NOISE: -117DBV unweighed input shorted
SENSITIVITY [Line Stage]: 26dB
INPUT IMPEDANCE: 100kOhms in parallel with 11pF

Mainframe

The “Mainframe” features all the switching and attenuator pots with internal sockets to accept the following modules:

Standard modules:

  • Master Out Line Stage Module [comes standard] Single-ended output.
  • Professional VU meter drive circuits.

Optional Modules:

  • Phono RIAA Stage Module Plug-ins
  • Balanced [transformer input] Microphone Preamplifier Module Plug-ins
  • 384kHz/24bit Digital to Analogue or Analogue to Digital converters.

All modules feature their own discrete voltage regulators.

Mains isolated power supply

The MIPS is essentially one channel of an IKARUS power amplifier driven by an ultra-low-noise discrete sine wave oscillator at ~ 200Hz driving the primary of an output transformer. The secondary of this transformer generates the filtered +/-35V dual mono supply rail voltages for the discrete voltage regulators. This scheme totally isolates the AC mains from the amplifier circuits.
 

 
 
 
 
 
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What the critics say...

The METAXAS OPUS stretches our acoustic expectations. At present, it defines the standard as to how far we can travel into the music... and it does so with style ...
— Martin de Wulf, BOUND FOR SOUND, USA
It would make a perfect tool to assess equipment by. If any component is not in the top league, the amps will betray the culprit with surprising honesty. Its other great strength is the speed of delivery. It can keep up with the fastest of guitar runs and tabla rolls with a speed normally associated with single-ended valve amplifiers
— Alan Sircom, HI FI CHOICE, England.
So neutral though, is the Metaxas Opus/Soliloquy set up that I could have used just about any sources I liked once the interconnecting cables were sorted. All I’d be hearing were the individual characteristics of the source components. However neutral or ‘naked’ the sound, the MAS doesn’t come off as ‘transistory’ or clinical... it had a feather-light touch and a way with tiny details that suggest either a pedigreed 60W or 70W per channel tube amp of recent vintage...
— Ken Kessler, HI FI NEWS& RECORD REVIEW, England.
From this moment on, “the miracle” from Metaxas brought out high frequency information with such clarity which was never before heard
— Rating: Absolute Spitzenclasse, REFERENCE. STEREO PLAY MAGAZINE, Germany.