Dynaco Dynakit ST-70 Tube Power Amplifier - SOLD
Dynaco is best remembered for its highly regarded vacuum tube stereo amplifier, the Stereo 70 (ST-70). Introduced in 1959, the ST-70 was available as a kit (Dynakit) intended for assembly by the purchaser or as a complete factory-wired unit (Dynaco). The ST-70 used four EL34 output tubes, one GZ34/5AR4 rectifier tube, two 7199 input (driver) tubes, two output transformers, one power transformer, and a pre-assembled printed circuit board (PCB) containing the driver circuit. It produced 35 watts per channel. The driver circuit had a single 7199 pentode/triode tube per channel, and used the driver tube to handle both voltage amplification and phase splitting. The output transformers are an ultralinear design, whereby part of the primary winding is fed back to the output tube’s screen grid. This design reduced distortion and improved audio quality.
A masterpiece of efficient circuit design, the ST-70 provided reliable, high-quality audio amplification at an affordable price. The popularity of the ST-70 contributed more than any other single product to continuing consumer interest in tube-based stereo amplifiers at a time of increasing market dominance by solid state audio products. Because of its excellent value, Dynaco tube amplifiers were often referred to as “the poor man’s McIntosh.” More than 350,000 ST-70s were sold when production finally ceased, making the ST-70 the most popular tube power amplifier ever made.
This Stereo 70 has been completely serviced and is in exceptional condition. The original driver board has been recapped, sports a pair of Sylvania "Old Stock" tubes, and a set of matching, measured & tested, "Old Stock" Svetlana EL34 tubes have been biased for proper output. This amp shows full output on our scope from 20-20,000 HZ, remarkable for a 60-year old piece of equipment!
Demos are available, but unfortunately shipping is not.
$799 (plus applicable sales tax)
* Does not include amp stand shown.