Quasi-complementary
circuitry tends to generage high order harmonic distortion and is particularly
susceptible to crossover distortion. To reduce theses types of distortion,
manufactures increase the amount of feedback within the amplifier. Under actual
dynamic conditions, however, the amplifier with exessive feedback is prone to
higher transient distortion and also lower stability.
In contrast, full
complementary symmetry output circuitry requires less feedback by incorporating
positive and negative amplifiers which are balanced to mirror-image each
other's characteristics. This design produces exceptional linearity, lower
total harmonic distortion and intermodulation distortion.
Early transistorized power amplifiers featured one of two types of output design. A transformer or a capacitor was incorporated between the power output stage and the speaker system. However necessary this was for proper output-to-speaker coupling, it tended to limit low frequency power response or to cause degrading phase shift, and thus impair sound accuracy.
Today's more advanced technology has eliminated the need for coupling transformers and capacitors and the sound inaccuracies they can cause.
A massive power transformer forms the heart of a dual-balanced positive and negative power supply that symmetrically powers the amplifier stages. large capacity electrolitic capacitors assure high energy power reserves, while massive heat sink promote highly reliable, long-term operation even under full power output conditions.
The more flexible
the tone controls, the more accurately you can adjust for non-linearities in
frequency response caused by speakers, speaker placement, room acoustics of the
program source itself.
the tone control
system in Marantz Models 2250B features a sophisticated
five-position tone turner/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 effect of the bass and treble controls to just the
desired range.
The three-stage, 40
dB gain amplifier built into Marantz receivers utilizes feedback-equalized
circuitry to maintain extremely low distortion the use of close
tolerance, stable components, such as tantalum input coupling capacitors, low
noise carbon film resistors, Mylar output coupling and polystyrene-type
equalization capacitors assures superior performance.
RIAA equalization is
precise - within +/-0,5 dB, from 20 Hz to 20 kHz - and under test in the 2325, the equivalent
noise input to the phono section measures a low 0,8 microvolts. The phono
overload point occurs at over 100 millivolts in the 2250B. These figures result in a dynamic range
capability of greater than 96 dB.
Superior selectivity
is assured by a four-gang tuning capacitor in the Marantz 2250B, and a dual-tuned RF interstage on Model 2250B provide excellent image and
spurious response rejection.
Marantz FET RF
amplifiers and mixer stages provide excellent spurious signal rejection and
extremely low noise operation that results in excellent quieting sensitivity.
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 performance quality than the IHF (Institute of High Fidelity)
sensitivity figure often quoted as the prime specification to consider when
evaluating an FM tuner.
The Phase Locked
Loop (PLL) design was developed originally to provide a state-of-the-art communication system for
the space industry. Today the same
technology is used in all Marantz tuners and receivers to assure you of low
distortion,excellent stereo separation and superior noise rejection.
PLL circuitry
positively locks to the stereo pilot signal broadcast by a FM station. This
precise "phase lock" is absolutely necessary for high performance in
the stereo demodulation process. It enables the multiplex demodulator to
separate the stereo channel information from the FM multiplex signal with more
accuracy and less distortion than multiplex demodulators using other designs.
SPECIFICATIONS 2250B
Rated Power
Output: 50 Watts (Minimum Continuous
Watts per Channel, Both Channels Driven)
Power Band: 20 Hz to 20 kHz
Total Harmonic
Distortion: 0,25%
Load Impedance: 8 ohms
I M Distortion (IHF
Method, 60 Hz and 7 kHz mixed 4:1 at Rated Power Output): 0,25%
Damping Factor (at 1
kHz): 55
Main
Inputs Sensitivity/Impedance: 1,5 V/33 kΩ
Frequency Response
(at 1W Output, 20 Hz to 20 kHz): ±20 dB
Pre-Amplifier
Section
Phono
Dynamic Range (Ratio
of Input Overload to Equivalent Input Noise):
96 dB
Equivalent
Input Noise (RMS, 20 Hz to 20 kHz): 1,5 μV
Input
Sensitivity and Impedance: 1,8 mV/47 kΩ
Frequency Response
(re. RIAA, 20 Hz to 20 kHz): ±1.0 dB
High Level Inputs
(Aux and Tape)
Input
Sensitivity and Impedance: 180 mV/100 kΩ
Output Impedance
Tape record: 200
Pre-Out: 900
Tone Controls
Bass: ±12 dB (50 Hz)
Mid: ±6 dB (700 Hz)
Treble: ±12 dB (15 kHz)
AM/FM SPECIFICATIONS
Quieting
Slope (Mono) 30 dB Quieting: 1,9 μV (10,8 dBf)
5 μV (19,2 dBf) : 55 dB
10 μV (25,2 dBf) : 60 dB
50 μV (39,2 dBf) : 70 dB
1000 μV (65,2 dBf) : 72 dB
Distortion
at 1000 μV (65 ,2 dBf, Mono)
100 Hz : 0,3%
1000 Hz : 0,3%
6000 Hz : 0,35%
Distortion
at 1000 μV 965,2 dBF, Stereo)
100 Hz : 0,45%
1000 Hz : 0,4%
6000 Hz : 0,55%
Distortion at 50 dB
Quieting (Mono and Stereo)
1000 hz : 0,6%
Hum
and Ni=oise at 1000 μV (65,2 dBf)
Mono : 70 dB
Stereo : 60 dB
Frequency Response
30 Hz to 15 kHz
Mono : ±1,0 dB
Stereo : ±1,5 dB
Capture Ratio
at 100
μV (45,2 dBf) : 2,0 dB
at
1000 μV (65,2 dBf) : 1,5 dB
Alternate
Channel Selectivity: 65 dB
Spurious Response
Rejection: 95 dB
Image Response
Rejection: 70 dB
IF Rejection
(Balanced): 100 dB
AM
Suppression at 100 μV (45,2
dBf): 60 dB
Stereo Separation
100 Hz : 38 dB
1000 hz : 40 dB
10 kHz : 30 dB
Pilot (19 kHz)
Rejection: 60 dB
AM
usable Sensitivity: 20 μV