Dynaco ST-70 Classic Tube Power Amplifier Pro Servuiced Excellent

  

DYNACO ST-70 Classic Vintage Legendary Stereo Tube Power Amplifier Restored in Excellent Condition. The Dynaco ST-70 Is a popular tube colle. Ctor power amplifier from the 1960's that offers high quality tube sound. This is your chance to get into the classic tube sound still popular with audiophiles. This amplifier was fully restored by the local TC Tubes and had capacitors and all needed electronic parts replaced so it is ready for long term trouble free use.

This was a kit wired amplifier and the wiring was checked and upgraded where necessary. The driver board was redone with new capacitors. The sound quality is excellent, full, and clean.

The tubes include; 4- New issue Electro Harmonix CA7EH output tubes, 2- RCA 7199 vintage tubes, and 1- 5AR4 rectifier Lifetime tube. The amp has the original Dynaco transformers.

The chassis is in very nice near mint condition and looks great with no pitting and the metal surface has moderate soiling which might be able to be cleaned. All lettering is present and excellent. The tube cage is excellent. This was a high cost restore. Included is the original Dynaco Instructions for Assembly and Operation manual in excellent condition.

This amplifier was minimally used since the restore. 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 for cost, Dynaco tube amplifiers were often referred to as the poor man's McIntosh.