Audio Database
Stereo-70
Commentary

A stereo power amplifier incorporating the basic design of the famous monaural power amplifier Mark-III as it is for stereo.

The output transformer is a custom-made output transformer made by Acrosound Inc., which was established by David Hafler, the founder of DYNACO.

By using spare parts throughout the entire circuit, aging due to long-term use is reduced.
In particular, the output tube is limited to 65% of the rated output, and the filter condenser is operated at less than 85% of the rated voltage.

Model Rating
Type Bulb type stereo power amplifier
Rated output 35W + 35W (20 Hz to 20 kHz)
IHF output 45W+45W
Maximum power output 80W+80W
Frequency characteristic 10 Hz to 40 kHz ± 0.5 dB
Total harmonic distortion factor 1% or Less (Rated Output)
0.05% or Less (at 1W Output)
Cross modulation distortion factor 1% or Less (Rated Output)
0.05% or Less (at 1W)
Signal-to-noise ratio 90 dB or more (at rated output)
Damping factor 20
Separation 55 dB or More (20 Hz to 20 kHz)
Input Sensitivity / Impedance 1.3 V (at rated output)
Output impedance 4 Ω, 8 Ω, 16 Ω
Accessory circuit Preamp Power Sockets (2 Pairs)
Dyna-bias set adjuster
Monaural / stereo selector switch
Vacuum tube used EL-34 (6CA7) : 4 pieces
7199 : 2 pieces
GZ-34 (5AR4) : 1 piece
Power consumption 190W
External dimensions Width 330x Height 165x Depth 240 mm
Weight 12.5kg