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K O S T A S
M E T A X A S D E S I G N
S p e c i f i c a t i o n s
14
OPTIONAL RIAA PHONO STAGE:
Input micro switches allow over 69 different combinations of input impedance, whilst
the phono input stage can be configured for operation with either Moving Magnet or
Moving Coil cartridges.The RIAA equalisation is generated via selected polystyrene
capacitors and 1% metal film resisters in the inverse feedback loop.
The overall open-loop gain of this stage has been optimised using local feedback in
the voltage gain stages to approximate the RIAA time constants before the applica-
tion of a minimal amount of overall feedback. This allows us to minimise the stability
compensation to ensure the high speed (greater than 10MHz) operation of this circuit.
The DC operating point is stabilised with the use of a low drift F.E.T. input servo Op
Amp which feeds micro-volts to the inverting arm of the differential input to entirely
eliminate the need for any input or output capacitors in the signal path.
S p e c i f i c a t i o n s
FREQUENCY RESPONSE : DC - 5.0MHz (-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 0.05% 20Hz-20KHz
I.M.D.(S.M.P.T.E.) : Less than 0.05%
SIGNAL/NOISE : -117DBV unweighed input shorted
SENSITIVITY : 26dB
INPUT IMPEDANCE : 100kOhms in parallel with 11pF
1. LINE STAGE: The MARQUIS Line stage is optimised for operation with any
incoming source including the modern Compact Disc playing machines. By
virtue of its dual-mono power supply with generous high voltage rails, it is
virtually impossible to overload. The preceeding VOLUME potentiometer
establishes the input impedance at a steady 10K Ohms.
By virtue of its high current transistor output stage with impedance of 50
Ohms, the MARQUIS is able to develop sufficient current to overcome the
increased capacitance of long (greater than 2 metres) interconnection
cables.
2. POWER SUPPLY: An external supply houses the completely dual-mono, high
current 46,000uF of primary filtering and stacked 100 Watt toroidal trans-
formers. The DC supply is connected via a 5 pin umbilical cord/socket
arrangement to the mainframe where the D.C. encounters another 10,000uF
of filtering before it reaches the regulation circuits. The regulation circuits
of the MARQUIS are generated by a proprietary circuit built around matched
and selected transistors. Absolutely no I.C's are used.
The positive Master is composed of a differential sensing circuit which on its
positive input is fed by a low noise zener which is amplified by a two-
transistor gain stage. The negative input monitors the output voltage to
ensure that the DC is stable and that the impedance of the regulator is
consistent at eliminating any AC component on the DC line (which is fed back
by the amplifier circuits) from effectively DC to at least 5MHz. Both
amplifier and regulator are tuned in conjunction with each other to maintain
an absolute stability and the highest possible speed of operation (the
regulators themselves have a linear frequency response from DC to beyond 5
MegaHertz).
The negative regulator consists of the same differential arrangement (with
current mirror) where the positive arm is tied to ground and the negative
input is a 'slave' to the positive Master. This ensures that the positive and
negative supplies are maintained at a constant voltage within millivolts of
each other, and eliminates the possibility of any untoward D.C. surges which
could adversely affect the DC servo circuits from maintaining absolute zero
level D.C. voltage components at the amplifier outputs.
3. D.C. PROTECTION: In the event of a D.C. voltage being generated on the
output of any of the amplifier stages greater than 0.6V, a dual F.E.T. inte-
grated circuit trips the relay in series with the output and short circuits the
input of the following amplifier to eliminate the possible damage of the
loudspeakers.
Summary of Contents for Marquis
Page 1: ...K O S T A S M E T A X A S D E S I G N Marquis K O S T A S M E T A X A S D E S I G N ...
Page 17: ...K O S T A S M E T A X A S D E S I G N Contr ols Featur es 15 ...
Page 19: ...K O S T A S M E T A X A S D E S I G N Maintenance 17 ...
Page 22: ...K O S T A S M E T A X A S D E S I G N Design Philosophy 20 ...