Technics EAA-2007/SU-2007/Technics 20A
¥ 135,000 (around 1966)
Commentary
High power stereo power amplifier with OTL circuit.
An OTL circuit is used for the circuit configuration. By wiring five new type 50HB26 beam tubes in parallel to the output tube, ordinary speakers can be directly connected.
We have also succeeded in reducing the distortion by minimizing the pre-NF distortion and limiting the amount of NF in the main loop to 30 dB or less. Moreover, by making the load resistance of each stage extremely small, the high-frequency characteristics are stable up to 200 kHz or more even without NF.
A 5-pole tube with excellent high-frequency characteristics is adopted in each stage, and large output can be taken out without strain up to high frequency.
The plates and screen power supply for the upper and lower stages of the SEPP are independent from each other, and the bridge method with small ripple voltage is adopted for the rectification of each plate stage, thereby suppressing hum during small output.
Equipped with a 2-stage switching mechanism that can switch between high output and low output.
Model Rating
Type |
Tube type main amplifier |
Music Power (1 kHz) |
High Power: |
100Wx2 (32 Ω, Distortion Factor 0.04% or Less) 80Wx2 (16 Ω, Distortion Factor 0.06% or Less) 40Wx2 (8 Ω, Distortion Factor 0.15% or Less) |
Low Power: |
35Wx2 (32 Ω, Distortion Factor 0.06% or Less) 18Wx2 (16 Ω, Distortion Factor 0.1% or Less) 12Wx2 (8 Ω, Distortion Factor 0.5% or Less) |
|
Rated Output (1 kHz) |
High Power: |
80Wx2 (32 Ω, Distortion Factor 0.04% or Less) 60Wx2 (16 Ω, Distortion Factor 0.1% or Less) 30Wx2 (8 Ω, Distortion Factor 0.2% or Less) |
Low Power: |
30Wx2 (32 Ω, Distortion Factor 0.06% or Less) 14Wx2 (16 Ω, Distortion Factor 0.2% or Less) 10Wx2 (8 Ω, Distortion Factor 1.0% or Less) |
|
Frequency Response (16 Ω Load) |
5 Hz ~ 100 kHz + 0 -0.5 dB |
S/N ratio (IHEM standard, ASA standard, A-curve) |
Input Short (1 hfm) High Power :
Low Power: |
100 dB (16 Ω) 105 dB (32 Ω) 97 db (16 Ω) 103 dB (32 Ω) |
Input Open High Power :
Low Power: |
92 dB (16 Ω) 97 db (32 Ω) 90 dB (16 Ω) 96 dB (32 Ω) |
|
Input sensitivity (at rated output) |
High Power: |
0.4 v (8 Ω) 1.0 V (16 Ω) 1.6 V (32 Ω) |
Low Power: |
0.3 V (8 Ω) 0.6 v (16 Ω) 1.2 V (32 Ω) |
|
Input attenuator |
3 dB step, -21dB decay |
Input impedance |
100k Ω |
Damping factor |
High Power : 50 (16 Ω) Low Power : 30 (16 Ω) |
Semiconductor used |
Vacuum Tubes (28 pcs) : |
6267 : 2 pieces 12AU7 : 2 Pieces 6BQ5 : 4 50HB26 : 20 pieces |
Diode (30 pcs) : |
SM-150A : 2 SM-150C : 4 SW-05B : 24 |
|
Pwer |
100 VAC, 50/60Hz |
Power consumption |
No signal : 500 VA Maximum power : 900 VA |
External dimensions |
Width 380x Height 185x Depth 370 mm |
Weight |
23.5kg |