Stax da 50 m owners manual

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DA-50M

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ALL-STAGE GROUND REFERENCE AMPLIFICATION PURE CLASS-A MONAURAL DC POWER AMPLIFIER

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Instruction Manual

STAX

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©lntroduction

The DA-SOM is a SQ watt monaural DC power
amplifier featuring an "AllStage Ground
Reference DC Amplifier Circuit".

This circuit was totally designed by STAX,
and is a world's first. STAX has been engaged
in research aimed at improving the quality of
pure class-A amplifiers in an effort to comple-
ment the excellent quality of our speaker
systems, earspeakers, and phono cartridges, all
employing electrostatic drive mechanisms,
The Super Shunt power supply used in the
CA-X and CA-Y is a result of that research.
This circuit was developed by us from the
ground up, based on our recognition of the
importance of power supplies in class-A
amplifiers. This "All-Stage Ground Reference
Circuit" clarifies the relationship between the
signal circuits and power supply, and confirms
the widely held belief that changes made to
power supply circuits produce changes in the
quality of the sound signal. With our success-
ful development of this new circuit, the signal
can be amplified without any coloration due
to noise from the power supply leaking into
the signal circuits. The audible difference is
clear- no muddv sounds. The DA-SOM is
also a fixed bias amp - completely different
from today's fashionable imitation class-A
power amps. It does not modify the sound
signal at all, merely amplifies its input.
Parts selection for the DA-SOM is also strict.
Each component is selected for the ultimate
in sound quality and reliability.

In order to derive maximum benefit and
enjoyment from your new amplifier, please
read this instruction manual carefully, then
store it in a safe place for future reference

Operation switch

0 As is noted in the front panel nomen-
clature section of this manual, the DA-
50M can also be operated as an AB class
amplifier with a maximum output of
saw, and the lowest 12.5 watts of this
range pure class-A operation. This feature
is particularly advantageous when using
high-efficiency speakers, or for night-time
listening when output rarely exceeds
12.5w. If the 12.5w display of the peak
level indicators only blinks occasionally,
the 12.5w range can be used with very
little affect on tone quality, and consider-
able power savings.

Protaction circuits

1. Short circuit protection: Short circuit-
ing the output terminals will overdrive the
output power transistors and destroy
them. This circuit controls current within
a safe operating range.

2. Thermal protection: This circuit serves
to protect the amplifier by sensing abnor-
mal rises in the temperature inside the
cabinet and cutting off the power supply.
3. Speaker protection: This circuit func-
tions to automatically cut off the power
supply, should an abnormal DC or transi-
ent surge (eg; dropping the tonearm on
record) appear at input, or in case the amp
itself should malfunction and pass t5VDC
to the output terminals. The speaker sys-
tem is thus protected.