ST70

About the ST70

The Dynaco Stereo 70 (ST-70) is a classic vacuum-tube stereo power amplifier introduced in 1959 by Dynaco and also sold in Dynakit form for user assembly. Designed by David Hafler, it uses a push-pull ultralinear Class AB output stage with four EL34/6CA7 power tubes and delivers approximately 35 watts per channel. Its combination of wide bandwidth, low distortion, selectable speaker-load taps, serviceability, and relatively compact size made it one of the most widely used and influential tube amplifiers in HiFi history. The original model is distinct from later Series II and Series 3 products. Original production has ended and the amplifier is now a vintage product; surviving examples may have been modified or restored, so performance can vary substantially with tube condition, capacitors, transformers, and circuit updates.