Power
Amplifier Section
High-Power
Full Complementary Symmetry Output
The mammoth
power of these Marantz receiver is generated by the most sophisticated full
complementary output stages in use. Transistor array is triple-paralleled in this 2385 - designs occasionally used
separate components, but never before in receivers. They help provide long
life, high power operation and exceptionally low Total Harmonic Distortion. As
low, in fact, as that of the Marantz 510M professional power amplifier.
Also like
the 510M, the Marantz 2385 are engineered to produce an extremely wide
safe operating area - that range where voltage, current and temperature
conditions permit reliable output stage operation. The amplifier sections are
so stable, they will drive a load at virtually any frequency or level without
breaking down.
In addition,
the output stages of both receivers are biased for Class AB operation, a
measure that prevents crossover distortion and ensures uncompromised
performance to well below 1/1000 of full rated power.
Output
device and speakers are guarded by a professional-calibre enrgy-sensing circuit
that doesn't limit the low energy, high amplitude short term transients
essential to accurate music reproduction. As a result, output signals are free
of the distortions and instabilities caused by conventional volt/amp limiting
circuitry used in most receivers.
Direct
Coupled Power Output
Provides
wide power bandwidth, excellent low frequency transient response and improved
damping factors. A number of high-power transistorized amplifiers still use
capacitor - or transformer-coupled output stages to ensure reliability. However
essential this design was in the past, it tended to limit low frequency power
response or cause degrading phase shift.
The Marant 2385 achieve their high degree of stability without the need for
coupling transformers and capacitors and the sound inaccuracies they can cause.
The benefits are extremely high damping factors at low frequencies and
excellent low frequency response.
Toroidal
Dual Power Supply
A specially
designed toroidal-core power transformer wwith dual secondaries gives you two
independent power supply sections. Each channel can perform at its best, at all
frequencies and levels, without affecting the other channel. In fact, even when
one channel is driven by a high level dynamic signal demanding considerable
power output, the other can still maintain exceptionally low distortion.
Complementing
the transformer are high-capacity dual section electrolytic capacitors. This
combination provides high power reserves, reliability and low distortion while
keeping heat and weight to a minimum.
.
Peak
Indicators
Both
receivers use the same type of sophisticated peak LED display featured in the
Marantz Model 510M power amplifier. Rather than simply sense the amp's output
voltage as in most LED displays, the unique Marantz circuit tracks variations
in the power supply. You get an accurate indication of maximum amplifier output
regardless of low or high AC line conditions. Peak indicators, unlike VU
meters, react instantaneously to audio transients or excessively high input
signals that cause clipping.
Tuner
Section
Steep
Quieting Slope
The quieting
slope specification measures a tuner's ability to provide good Signal-to-Noise
performance
Under actual
operating conditions. It's a far more reliable indication of quality than the
IHF sensitivity figure often quoted as the prime specification to consider when
evaluating an FM tuner.
Highly
Sensitive Dual-Gate MOSFET FM Front End
The superior
quieting sensitivity of Models 2385 is largely due to the use of a
dual-gate MOSFET RF amplifier and mixer stage. Moreover, MOSFET devices deliver
extremely linear operation, providing low RF intermodulation distortion and
excellent rejection of spurious signals.
An
outstanding selectivity specification is ensured by a five-gang tuning
capacitor, while a dual-tuned RF interstage provides improved image and
spurious signal rejection.
Phase Locked
Loop FM Stereo Demodulator
The phase
locked loop (PLL) design was developed by the space industry to provide a
state-of-the-art. Communication system. Today the same technology is used in
all Marantz receivers and tuners to assure low distortion, supoerior noise
rejection and excellent stereo separation.
PLL
circuitry locks to the stereo pilot signal broadcast by an FM station. This
positive "phase lock" enables the multiplex demodulator to separate
the stereo channel information from the FM multiplex signal with more accuracy
and less distortion than demodulators using other designs.
PLL is
dependent on pilot phase and not on pilot aamplitude, making it less
susceptible to false triggering from various types of noise interference.
Multi-Stage
IF Section
Built into
both receivers is a comprehensive six-stage IF amplifier section incorporating
five dual-element ceramic filters. The characteristics of these filters produce
a 200 kHz passband which is linear in phase, consequently eliminating a major
source of high frequency distortion and loss of stereo separation. Sharp
cut-off slopes improve tuner selectivity, assuring superior reception even when
stations are closely spaced. A
multi-stage limiter comprised of two integrated circuits provides superb AM
rejection and an excellent capture ratio - specified at 1 dB. Distortion (at 1
kHz) is kept at a minimal 0,1% in mono, and 0,2% in stereo.
Plug-in
Dolby FM Capability
On the back
panel of Model 2385 is a convenient receptacle that accepts the optional
plug-in Marantz DLB-1 Dolby FM Decoder. Inside the receivers is a
25-microsecond Dolby FM equalization circuit. In tandem, they can cut the noise
from a Dolbyized FM broadcast by as much as 12 dB.. That's the equivalent of
reducing the noise power of a received FM signal sixteen times below normal.
Additional Features
The Model 2385 receiver have a multiplex noise filter that reduces the background
noise of weak FM stereo signals, while maintaining full frequency response. And
they feature adjustable FM muting, a pivoting
AM antenna and an "F" connector for simple connection of
coaxial FM antenna cable.
Preamplifier
Section
Flexible
Tone Controls
The more
flexible the the tone controls, the more accurately yoy can adjust for
non-linearities caused by speakers, speaker placement, room acoustics or the
program material itself.
The tone
control system in Marantz Model 2500; 2385 features a sophisticated
five-position tone turnover/mode switch for versatile bass, midrange and treble
control. This eliminates a major shortcoming of conventional tone controls -
their tendency to affect too wide a band of frequencies. Optional frequency
turnover points limit the bass and treble controls to just the desired range.
The
advantages can be illustrated by a practical example: boosting the low bass
(under 100 Hz) to compensate for a deficiency in room acoustics. Most
conventional tone controls, even if capable of supplying the boost, will also
increase the output in the 300 Hz to 1,000 Hz region.
With the
turnover point set at 100 Hz on a Marantz receiver, the bass control can
provide the desired bass boost up to the frequency point of 100 Hz and leave
the frequency range above the point essentially flat and unaffected.
This
flexible, easy-to-set system permits a virtually unlimited number of repeatable
settings, enabling you to adjust for the desired tonal balance in any listening
environment.
Precision
Four-Gang Volume Control
Model 2385 feature a precision-calibrated, stepped volume control. Its superb
tracking accuracy of ±0,5 dB between left and right channels enables you to
repeat volume settings with total accuracy.
The
four-gang design helps produce exceptional Signal-to-Noise performance -
typically greater than 10 dB over conventional volume control designs.
Superior
Filter Design
The Model 2385 feature an 18 dB per octave Bessel-derived high filter - the most
advanced filter design in audio. It reduces high frequency noise - and produces
a more natural less colored sound because it eliminates the overshoot and
"ringing" common to other filters. Results are linear phase response
and greatly reduced phase and transient distortion. An 18 dB/octave 15 Hz
subsonic Butterworth low filter cuts turntable rumble and subsonic transients
that prevent accurate reproduction of low frequency signals.
Never before
has such advanced filter technology been applied to any audio components,
separates or receivers. 18 dB/octave filters provide positive filtering action
with little coloration of sound by concentrating their effect only at the
specified frequencies. Filters with slower roll-off characteristics, on the
other hand, must start acting toward the midpoint of the frequency range in
order to perform adquately at the extreme high or low end of the audio
spectrum.
Flexible
Tape Copy Functions
In addition
to the standard phono and auxiliary inputs, two sets of tape inputs and outputs
are provided to facilitate dubbing between a pair of tape decks. A built-in
tape copy facility can function independently of program selector and tape
monitor circuitry, enabling you to dub from one deck to another while listening
to a different program sourece.
Also
featured are front-panel dubbing jacks that allow you to add a third tape deck
without disturbing any rear panel connections.
Reat panel
facilities include conections for two sets of speaker systems, main in/pre out
jack's a Quadradial output jack and two convenience AC outlets.
Specifications
Amplifier
Section
Minimum
Continuous Power per Channel (from 20 Hz to 20 kHz, both channels driven):
Into 8 ohms
: 185 W
Into 4 ohms
: 240 W
Total
Harmonic Distortion
At 8 Ω
: 0,05%
At 4 Ω
: 0,1%
IM
Distortion (IHF method, 60 Hz : 7 kHz = 4:1 at rated power output):
at 8 Ω :
0,05%
At 4 Ω
: 0,1%
Damping
Factor (at 20 Hz): 60
Preamplifier
Section
Phono
Input
Overload at 1 kHz : 200 mV
Equivalent
Input Noise "A" weighted: 0,48
µV
Dynamic
Range: 113 dB
Input
Sensitivity at 1 kHz : 1,8 mV / 47 k Ω
Signal-to-Noise
Ratio "A" weighted (at rated output & 7,75 mV Input): 83 dB
Frequency
response (RIAA, 20 Hz to 20 kHz): ±0,25 dB
Input
Capacitance: 100 pF
High Level
Inputs (Aux & Tape):
Input
Sensitivity/Impedance : 180 mV /47 k Ω
Signal-to-Noise (A weighted):
98 dB
Output
Impedance
Tape Out
: 500 Ω
Pre
out: 50 Ω
AM/FM Tuner
Section
Sensitivity
IHF Usable
[mono]: 8,75 dBf (1,5 µV)
IHF -50 dB
Quieting
Mono : 12,1 dBf (2,2 µV)
Stereo
: 33,2 dBf (25 µV)
Quieting
Slope (mono)
RF input for
30 dB Quieting: 6,8 dBf (1,2 v)
Quieting at:
20 dBf (5,5
µV) : 58 dB
25 dBf (10
µV) : 66 dB
40 dBf (55
µV): 78 db
65 dBf
(1,000 µV): 80 dB
Quieting
Slope (stereo)
Quieting at:
30 dBf (17
µV) : 49 dB
45 dBf (55
µV) : 62 dB
50 dBf (173
µV): 70 db
65 dBf
(1,000 µV): 75 dB
Distortion,
Mono and [stereo] at 65 dBf:
At 100 Hz
: 0,15% [0,35%]
At 1,000 Hz
: 0,1% [0,2%]
At 6,000 Hz
: 0,15% [0,3%]
Hum and
Noises (at 65 dBf) Mono : -80 dB
Frequency
Response (30 Hz to 15 kHz)
Mono and
Stereo : +0,2 dB -1,0 dB
Capture
Raatio: 1 dB
Alternate
Channel Selectivity: 85 dB
Spurious
Response Rejection: 120 dB
Image
response Rejection: 120 dB
IF
Rejection(balanced): 120 dB
AM
Suppression: 60 dB
Stereo
Separation
At 100 Hz
: 45 dB
At 1,000 Hz
: 50 dB
At 10,000 Hz
: 42 dB
Subcarrier
rejection: 75 dB
AM Usable
Sensitivity (IHF): 10 µV
AM
Distortion at 30% Modulation: 0,4%
AM
Signal-to-Noise Ratio: 55 dB
Dimensions
(W x H x D): 491 x 178 x 435 mm
(19-1/4" x 7" x 17-1/8")
Weight: 27 kg (59,4 lbs)
