Metaxas Solitaire Power Amplifier update

Official info and photos about the avantgarde Metaxas Solitaire Power Amplifier…

"The Solitaire is a straight 150 WRMS Stereo Power Amplifier or can be offered like the IKARUS as a higher powered [150WRMS] Stereo Integrated Amplifier. It embodies the sculptural design and “lack-of-sound” philosophy of Metaxas & Sins….


A prominent audio designer once described an amplifier as “A straight piece of wire with gain”. We take this further by featuring the shortest possible signal path in a commercial amplifier. We minimize wire in any of our signal path and every component is directly soldered to one large printed circuitboard. From input to output, the signal passes through no more than 150mm of P.C.track.

The transformer is connected with only 40mm of wiring to the PC board. This is only possible with our unique construction which features the complete amplifier (including filtering capacitors) is assembled onto one single rectangular Printed Circuit Board where the four sides connect directly to the inputs and outputs, power transistors on their heat sinks and power transformer.

The audio signal passes through ONLY ONE TYPE OF WIRE which is the high speed, wave controlled oxygen free copper of our PC board.


Conventional power amplifier use a large, high-current power transformer which feeds a ‘high-current’ bridge rectifier to convert the AC from the transformer into DC voltages which are then mains ripple filtered using massive, computer grade capacitors.The rectifier bridge that is normally used is relatively large, handles high- current and low voltage with very slow switching speeds because of its inherent high internal capacitance. It has a response time measured in milliseconds which if converted to fre-quency would mean that it would have a frequency response from DC to around 200Hz.

Frequencies above 1 kHz would be unable to draw current instantaneously from the power transformer and would need to rely on the charge stored in the power supply filtering capacitors. We replace this slow DC rectifier with ultra high speed diodes wired inparallel with switching times in ‘nanoseconds’ which when converted to audio frequencies have a frequency response from DC-10 MegaHertz. High and low frequency currents can be drawn from the power supply more effortlessly.


The most significant difference between VALVE and TRANSISTOR circuits is the amplifier/power supply interaction.

In VALVE amplifier, the high voltages (from 200-400 Volts DC) result in a 50,000 to 100,000 Ohms value for resistor R. The equivalent transistor amplifier using much lower voltages (from 12-30 Volts) would have a substantially lower value of R between 200 Ohms-100 Ohms.

A normal power supply in a transistor amplifier is more likely to affect the transistor amplifier circuit compared to a Valve amplifier circuit. If we assume that the regulator impedance at V+ is around 2 Ohms just for the purpose of this illustration, then let us study the amplitude of the 10VOLT sine wave as it goes through R and returns back to the OUTPUT of the TRANSISTOR circuit and VALVE circuit. In the VALVE circuit, when 10 VOLTS travels across the 50,000 Ohms R towards the power supply impedance of 2 Ohms , the 10V signal is attenuated 50,000/2 = 25,000 times.

Therefore 10V/25,000 = 0.0004 Volts of 1,0kHz sinewave. On its way back to the OUTPUT of the circuit it is attenuated by the impedance of the amplifier (say 100 Ohms): 0.0004 Volts/50,000/1,000 =0.000008 Volts. 0.000008 VOLTS of out of phase sine wave accompanies the 10 Volts sine wave as out-of-phase distortion in the VALVE CIRCUIT.

In a normal TRANSISTOR circuit, the 10 VOLTS going across the 200 Ohmsresistor R would be attenuated only 10/200/2 = 0.1 VOLTS. On the way back to the output, the voltage is attenuated by: 0.1V/200/1000 = 0.05 VOLTS ofout-of-phase sine wave added to the 10 VOLT output sine wave In a normal Transistor circuit, the ‘phase distortion’ is 0.5% as compared to 0.000008% for a normal VALVE circuit .

Our amplifiers have been designed using a variety of state-of-the- art phono playback equipment over the years but our ABSOLUTE REFERENCE is our library of over 300 in-house Master Tapes of acoustic Jazz and Classical concerts recorded using our Metaxas-modified battery-powered Stellavox SM-8 [and TD9]Tape Recorders with AGFA 468 1/4” tape recording using Bruel & Kjaer 4135 1/4” instrumentation and modified NEUMANN TLM-50 and M150 condensor microphones.

Digital copies of these recording “Masters” are freely available to our customers."

POWER OUTPUT: 150WRMS per channel into 8 Ohms
with no more than 0.05% T.H.D.
DAMPING FACTOR : Greater than 500 wide band
SLEW RATE : Greater than 1000V/us small and large signal T.H.D. : Less than 0.05% 20Hz-20KHz
I.M.D.(S.M.P.T.E.) : Less than 0.05%
SIGNAL/NOISE : -117DBV unweighed input shorted SENSITIVITY: 0.5VRMS in for 150WRMS out (28dB)
INPUT IMPEDANCE : 100kOhms in parallel with 11pF