Dynaco ST 150 power amplifier

Dynaco ST 150 power amplifier
The Dynaco Stereo 150 is a basic two channel power amplifier employing all silicon semiconductors.

They include 24 transistors, 2 zener diodes, 16 diodes, and 2 thermal sensors. The output circuitry is of the full complementary symmetry design. The entire amplifier, except for an input network, is direct coupled.

It's measured distortion levels approach the threshold of much laboratory test equipment, not only at the commonly specified full power ratings, but more importantly at very low power outputs as well.

This is the result of circuit techniques which eliminate any discernible crossover notch at low levels, and contributes to the Stereo 150's freedom from listening fatigue.

It's accurate, uncoloured sonics have been achieved on a wide variety of loudspeaker loads, including electrostatics and multiple drivers with complex crossovers.

The design of a very fine power amplifier implies the necessity of several protection techniques for the amplifier, and for the speaker load. In addition to the AC line fuse, four separate B+ fuses are supplied.

Electronic volt-amp limiting ensures safe operation of the output transistors, and a thermal sensor mounted directly on each output stage reduces the input if high temperature occurs.

An unusually large radiating area for the heat fins, which are coupled to an aluminium back panel, form a highly efficient heat sink. Speaker fuses protect the load.

The Stereo 150 has been designed as two independent 75 watts (at 8 ohms) amplifying channels with a common power supply having a high degree of inherent regulation.

In addition, where higher powers or higher volt-amp capabilities are required for lower load impedances, easy internal restrapping permits monophonic operation for 150 watts output (at 8 ohms).

An accessory kit is planned at additional cost for two output meters and meter switching, which includes alternative inserts for the front panel.

Specifications
Power output: 75 watts per channel into 8Ω (stereo)

Frequency response: 20Hz to 20kHz

Total harmonic distortion: 0.25%

Damping factor: 50

Input sensitivity: 1V

Signal to noise ratio: 95dB

Speaker load impedance: 4Ω to 16Ω

Semiconductors: 24 x transistors, 2 x zener diodes, 16 x diodes, 2 x thermal sensors

Dimensions: 14.5 x 13.75 x 7 inches

Weight: 29lbs