Hitachi SR 2004

 Hitachi SR 2004 with its exclusive Class G amplifier delivers 200 watts per channel RMS into 8 ohms with only 0,08% THD. But during demanding musical peaks, that unique amplifier does an amazing thing. It actually doubles its power to 400 watts per channel RMS to prevent any possibility of clipping or distortion. There is no known speaker system or musical recording that the SR 2004 cannot handle effortlessly and magnificently.

 Its host of advanced features include FM auto-lock, FM muting, phase lock loop circuitry, power protection circuit,mic mixing, hi/low filters, dual power meters, detent control, 3 pairs of speaker connections, switches and indicator lights.

For those who want the power and performance of the finest separate components in a compact receiver there is one incomparable answer.  The Hitachi SR 2004

 Features Tuner Section

Dual Gate MOS FET for High Quality FM Tuner

Auto-Lock Circuit

IF BAN D Selector Switch for Flexible Selectivity and SAW FI LTER for Low Distortion

High-Selectivity and Low-Distortion IF Amplifier using IC's and 3 Ceramic Filters

Quadrature Detection

Phase-Locked Loop IC for FM/MPX Circuit

Reed Relays for Cutting out Detuning Noise

MPX NOISE FILTER

FM MULTIPATH Switch with Meter for Best FM Reception

3-gang Variable Capacitor for High Selectivity AM Reception

Ceramic Filter, ICs in AM Tuner

Two Large Easy-to-Read Meters and a Large-sized Flywheel Tuning Knob

 Audio Section Features

Newly Developed High-Efficiency High-Power Audio Amplifier (Series E ..... Class G or Dynaharmony Amplifier)

Twin Power Meters (L and R channels)

Midrange Tone Control

Turnover and Tone Defeat Switches

Calibrated Attenuator (Volume Control)

Audio Muting Switch

Mic Mixing

Tape Dubbing

Low Filter and High Filter

Three Speaker Systems Connection

Electronic Protection Circuit

Adaptor Switch

 DESCRIPTION OF THE NEW CIRCUIT

SAW filter

FM-IF section of this model is so designed that 2 types of the frequency band characteristics (WIDE, NARROW) can be selected.

Namely, when the IF band switch is set to WIDE, the SAW fIlter and 4-pole linear phase filter are used to suppress distortion to a minimum to improve the group delay characteristics. When the IF band switch is set to NARROW, 2 ceramic filters are used in addition to the above SAW filter and the 4-pole linear phase filter to improve selectivity characteristics. In addition, amplification is performed by IF Amp to compensate for losses caused by insertion of the two ceramic fIlters.  Accordingly, positioning at NARROW is convenient when there is interference from a station close by when receiving a long distant station.

Dynaharmony (Class G Amplifier) output circuit

The level of the music source changes momentarily, the percentage of high level (over 1/2 of peak value) is very small, it is only less than 2% of the total music signals.

Large output amplifiers have been used conventionally to playback at high levels without distortion; however, in this case, high voltage is impressed to the output transistor, so the power consumption is large.

Studies have been made, how to obtain high output powers without the increase of the output transistors' consumption in order to improve the efficiency. Thus, the new dynaharmony output circuit (Class G Amplifier) was developed.

Current mirror circuit

This set contains a current mirror circuit which drives the output stage in push-pull operation to keep distortion low.

Constant current circuit

This constant current circuit stabilizes the bias of the main amplifier circuit.

Idle current compensation circuit against power supply voltage fluctuations

Protection circuits

(1) Muting circuit

(2) ASO (Area of Safety Operation) detection circuit (output transistor protection)

(3) DC voltage detection circuit (speaker protection)

Specifications

FM Section

Frequency Range:  88 - 108 MHZ

Usable Sensitivity [Mono/Stereo]:  8,7 dBf (1,5µV) / 24 dBf (8,9µV)

50 dB Quieting Sensitivity [Mono/Stereo]:  12,5 dBf (2,3 µV) / 36 dBf (34,5 µV)

Signal-to-Noise Ratio (at 65 dBf)[Mono/Stereo]:  75 dB / 70 dB

Harmonic Distortion (at 65 dBf)

Narrow [Mono/Stereo]:

100 Hz :  0,15% / 0,25%

1 kHz :  0,1% / 0,2%

6 kHz :  0,25% / 0,3%

Wide [Mono/Stereo]:

100 Hz :  0,15% / 0,25%

1 kHz :  0,07% / 0,1%

6 kHz :  0,2% / 0,3%

Frequency Response:  30 Hz - 15 kHz  +0,5 -1,0 dB

Image Response Ratio:  115 dB

Spurious Response Ratio:  120 dB

IF Response ratio:  115 dB

Alternate Channel Selectivity [Narrow/Wide]:  85 dB / 45 dB

Capture ratio:  1 dB

AM Suppression:  60 dB

Stereo Separation:  50 dB (1 kHz)

Sub Carrier Suppression:  70 dB

SCA Rejection:  70 dB

Muting Threshold:  28 dBf (14 µV)

Antenna Input:  300 Ω balanced, 75 Ω unbalanced

AM Section

Frequency Range:  530 - 1605 kHz

Sensitivity:  370 µV/m (S/N 20 dB), 20 µV (IHF, ext. Antenna)

Image rejection:  70 dB

IF Rejection:  90 dB

Selectivity (IHF):  40 dB

Signal-to-Noise Ratio:  50 dB

Antenna:  Ferrite and Separate terminal

Audio Section

Output RMS Power (both channel driven):  200 watts per channel, min. RMS at 8 Ω from 20 -20,000 Hz, with no more than 0,08% THD

Music Power (IHF):

230 W + 230 W per channel at 8 Ω, 1 kHz, THD 0,08%

230 W +230 W per channel at 4 Ω, 1 kHz, THD 0,1%

400 W + 400 W per channel at 8 ohms

Power Bandwidth:  10 Hz - 40,000 Hz

Frequency Characteristics:

Phono : 30 Hz - 15 kHz  ±0,2 dB

AUX :  10 Hz - 40 kHz  ±1,5 dB

Harmonic Distortion

Less than 0,08% at rated output

Less than 0,03% at ½ rated output

Intermodulation Distortion

0,08% at rated output

0,03% at ½ rated output

Input Sensitivity/Impedance (at 200 W output, 1 kHz):

Phono 1, 2 :  2,5 mV /47 k Ω

Aux :  150 mV / 50 k Ω

Tape 1, 2 :  150 mV / 35 k Ω

Adaptor :  150 mV / 35 k Ω

DIN :  450 mV/ 95 k Ω

MIC :  3 mV / 50 k Ω

Max. Input Level (Phono):  500 mV

Output Level (Tape Out) :

150 mV (Phono, Aux at rated input)

200 mV (FM 400 Hz, 30% dev. Input: 1 mV)

150 mV (AM 400 Hz, 30% mod.input: 5 mV/m)

Output level DIN Out:  40 mV (Phono at rated  input)

Signal-to-Noise Ratio (IHF, Input shorted, A-network, rated power):

Phono 1, 2 :  75 dB

Aux : 90 dB

Tape 1, 2 :  90 dB

Damping Factor:  75 (1 kHz, 8 Ω)

Equalizer:  RIAA ±0,2 dB

Bass Control

±10 dB at 50 Hz turnover frequency 150 Hz

±10 dB at 100 Hz turnover frequency 300 Hz

Midrange Control

±6 dB at 1 kHz

Treble Control

±10 dB at 10 kHz turnover frequency 3 kHz

±10 dB at 20 kHz turnover frequency 6 kHz

Loudness Control (Volume control set at -33 dB position):  +9 dB (100 Hz);  =4 dB (10 kHz)

High Filter:  -10 dB at 10 kHz  (12 dB/oct)

Low Filter:  -10 dB at 50 Hz  (12 dB/oct)

Audio Muting Effect:  -20 dB;  0 dB;  -40 dB

Tape Monitor:  1,2

Speaker Switch:  A, B, C, A+B, B+C, C+A, OFF

Tuning Meter:  2

Power Meter:  2

AC Outlet:  3 (one switched 50 W &2 unswitched total 150 W)

Speaker Terminal:  One touch terminal

FM Muting / Auto Lock:  provided

MPX Noise Filter:  provided

IF Band Filter:  Narroe and Wide

Multipath Filter:  provided

Pre/Main Amplifier:  separable

Adaptor Switch:  provided

Power Supply:  AC 120 - 220 V 50/60 Hz

Power Consumption:  850 W

Dimensions (W x H x D):  580 x 186 x 447 mm (22 ¾" x 7 ½" x 17 ½")

Weight:  25,5 kg (56,2 lbs)