Eroica EW-50S
Price unknown (around the mid 1960 s?)
Commentary
This is a stereo power amplifier developed with the ultimate aim of amplifier.
The transformer developed jointly with tamura Manufacturing Co., Ltd. is used as the output transformer.
This transformer employs a new method for coupling a tertiary winding (tamura Patent) exclusively for NFB with a circuit unique to ELOICA.
KT-66 is used for the output tube.
The circuit design employs a two stage low-frequency time constant, a high gain in the loop using a cathode-coupled phase inversion circuit with a good balance, and a stable method of returning NFB from the secondary side of the output transformer to the cathode of the first stage tube.
The NFB is 24 dB.
Model Rating
| Type | Power amplifier |
| Output | 27W + 27W (continuous output) 40W + 47W (peak output) |
| Output impedance | 4 Ω, 8 Ω, 16 Ω |
| Harmonic distortion factor | 0.1W output 0.25% or Less (50 Hz) 0.07% or Less (1 kHz) 0.05% or Less (10 kHz) At 1W output 0.2% or Less (50 Hz) 0.1% or Less (1 kHz) 0.2% or Less (10 kHz) At 10W output 0.3% or Less (50 Hz) 0.4% or Less (1 kHz) 0.3% or Less (10 kHz) At 28W output 0.9% or Less (50 Hz) 0.5% or Less (1 kHz) 0.5% or Less (10 kHz) |
| Signal-to-noise ratio | -94dB or less |
| Residual noise | 1 mV or less |
| Output characteristic | Maximum power 27W 15 Hz to 30 kHz ± 1 dB At 10W output 14 Hz to 40 kHz ± 1 dB At 1W output 12 Hz to 50 kHz ± 1 dB 0.1W output 10 Hz to 80 kHz ± 1 dB |
| Frequency characteristic | 13 Hz ~ 45 kHz ± 1 dB (at 5W Output) |
| Input sensitivity | 0.6 V (input voltage required for 27W output) |
| Used vacuum tubes, etc. | Vacuum tube KT-66x4 12AT7x1 12AU7x2 Silicon diode DS1Mx2 |
| Power consumption | 170 VA (No Signal) 210 VA (at maximum signal) |
| External dimensions | Width 235x Height 175x Depth 345 mm |
| Weight | 16kG |