Technics SA-5770

1 9 7 7 1977
1 9 7 8 1978

Prefiguration of the not-so-well remembered SA-1000 mammoth and probably quite a "sleeper" as such.

Still a bit hectic inside... and with only two (big) smoothing caps instead of four, but the heatsinks are the same, so is the RF varicap and so are most of the (many) functions.

Power amp
DC full complementary OCL circuit
Each differential amp uses a single-package dual-transistor (A798 56F) with a 100% DC feedback circuit.
Emitters/followers follow the differential first stage.
Pre-driver stages are constant-current loaded Class A amplifiers.
Parallel push-pull output.
Multiple protection circuits with overload alarm

Low-noise, overload-resistant phono EQ section.
First stage is a differential amp with current mirror load.
Second stage is low-distortion Class A amp which drives the SEPP output circuit with low impedance.
Detented volume control with 26 2dB steps
Low distortion tone controls with three-stage DC circuit and tabilized differential amplifiers (1st stage) and SEPP output (final stage)

4-gang dual-gate MOS-FET Mixer with point-to-point wiring in the FET buffer-equipped local oscillator
Flat group-delay ceramic filters with 6 stages of differential amplification by way of constant-current supply and three ICs and discrete stages
Independent IF control circuit, high-linearity detector with select detector diodes
FM MPX PLL IC with double-differential switching
300% overmodulation tolerance
Stabilized and regulated tuner power supply
Quality AM section with IC and double-tuned LC filter in the IF circuit
Phase delay switch

Technics SA-5770, image 1 Technics SA-5770, image 2 Technics SA-5770, image 3
Technics SA-5770 specifications
Title Value
PRE / MAIN section PRE / MAIN section
RMS power output : 2x 165W (20Hz...20Khz, 8 Ohm, 0,08% THD)
20Hz...20Khz continuous power output : 2x 205W (20Hz...20Khz, 4 Ohm, 0,08% THD)
1Khz power output : 2x 175W (8 Ohm, 0,08% THD)
2x 230W (4 Ohm, 0,08% THD)
THD : 0,08% at rated power (20Hz...20Khz)
0,05% at half rated power (20Hz...20Khz)
0,015% at helf rated power (1Khz)
IMD : 0,01%
Damping factor : 60 (8 Ohm)
30 (4 Ohm)
Inputs : 2,5mV / 25 - 50 - 100kOhm (phono 1 & 2)
2,5mV / 50kOhm (lines)
Outputs : 200mV (tape REC)
Maximum input level : 20mV (1Khz, RMS)
S/N ratio : 78dB (phono, IHF A)
95dB (lines, IHF A)
Frequency response : ±0,2dB (RIAA, phono)
20Hz...20Khz (+0 / -0,3dB)
Bass control : ± 12dB @ 50Hz
Bass turnovers : 250Hz / 500Hz
Treble control : ± 10dB @ 10Khz
Treble turnovers : 2,5Khz / 5Khz
Loudness control : +10dB @ 50Hz
Low filter : 12dB/octave below 30Hz
High filter : 12dB/octave above 7Khz
FM section FM section
Sensitivity : 10,3dBf
1,8µV (IHF'58)
50dB quieting : 12,8dBf (2,4µV IHF'58, mono)
35,7dBf (33,4µV IHF'58, stereo)
THD : 0,1% / 0,15% (100Hz, mono / stereo)
0,1% / 0,15% (1Khz, mono / stereo)
0,2% / 0,4% (6Khz, mono / stereo)
S/N ratio : 85dB (hi-lag, mono)
75dB (hi-lag, stereo)
Hi-Lag frequency response : 20Hz...15Khz (+0,2 / -0,8dB)
Const frequency response : 20Hz...18Khz (+0,2 / -0,8dB)
Alt channel selectivity : 80dB
Capture ratio : 1,0dB
Image rejection : 85dB (98MHz)
Spurious response rejection : 100dB (98MHz)
AM suppression : 100dB (98MHz)
Stereo separation : 60dB
45dB (1Khz)
Carrier leak : 38dB (10Khz)
Terminals : -65dB (19Khz, 38Khz)
75 Ohm
300 Ohm
AM section
Sensitivity : AM section
Selectivity : 30µV, 250µV/m
Image rejection at 1Khz : 22dB
IF rejection at 1Khz : 47dB
PC : General
Dimensions : 430W max.
Weight : 59 x 18 x 49,3cm
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