Hafler DH-200 Assembly And Operating Instructions Manual page 2

The Hafler DH-200 is a two channel audio power amplifier
designed to the very highest performance standards. It is
available either as a kit, or fully assembled. Its 100 watt per
channel power rating is sufficient for driving all
loudspeakers in home applications, and its design provides
extremely low distortion of all types. A combination of high
performance, dependability and reliability, and moderate
price is in the Hafler tradition of using the latest technology
to provide outstanding value.
Combining the latest power MOSFET technology with
uniquely simple and effective circuit topology reduces distor­
tion of all types, and at all power levels, over the full audio
frequency spectrum, to the vanishing point. In addition to its
pace-setting performance achievements, the conservative
mode of operation accomplishes a new high in long term
reliability and exceptional resistance to abusive operating
conditions. This is one of the direct benefits of MOSFET
utilization in overcoming a serious limitation of conven­
tional transistors — their tendency to self-destruct under
other than normal operating conditions. So rugged is the
DH-200 that it can deliver as much as ten amperes into a
short circuit!
The speed — measured as the slew rate — of this design
delivers unmatched transient linearity, revealing the most
delicate shadings, textures and nuances of the music, surpass­
ing the capabilities of the most revealing loudspeakers and
cartridges by a wide margin. Coupled with its unconditional
stability, and ability to deliver adequate power into any
loudspeaker load, the result is absolute freedom from listen­
ing fatigue. The longer you listen to this phenomenal
amplifier, the more certain you will be that you could not
have made a better choice.
Though modest in cost, the DH-200 evidences the very
finest electrical and mechanical design. It avoids costly frills
and unnecessary gadgetry while providing quality sound and
reliability based on top grade components conservatively
operated.
Operation
Assembly Instructions
Wiring the Kit
If Problems Arise
Service and Warranty
© Copyright 1980. All rights reserved.
INTRODUCTION
The oversized power transformer and bridge rectifier; the
massive heat sinks; the conservative operating levels of the
MOSFET output devices — all are evidence of the design
efforts to achieve exceptional reliability simultaneously with
state of the art sonics and specifications. And this circuit is
convertible (with an internal accessory bridging circuit
board) to a high power monophonic amplifier with
equivalent stability and specifications.
The fully complementary, symmetrical push-pull circuit,
which is direct coupled throughout (except at the input), in­
corporates all silicon devices in a format which is directly
related to the highly acclaimed DH-101 preamplifier. Its
unique self-protecting output stage prevents the thermal
runaway which is a common threat to solid state amplifiers.
The ruggedness and conservative operation of the output
stage allows the DH-200 to avoid the need for special protec­
tive circuits which could compromise audio performance.
Basic protective systems provide maximum security against
malfunction damage to the amplifier or the speaker: the A C
line fuse, B+ fuses, thermal breakers, and loudspeaker fuses.
Nothing hinders the essential purity of the audio signal.
Those who use these instructions to assemble the
DH-200 kit will find that the left and right audio modules
(printed circuit and heat sink assemblies) are preassembled
and pretested. This greatly simplifies the kit assembly so that
it can be done in only a few hours without special skills or
know-how. Because of the modular arrangement, it is possi­
ble to operate on one channel if the other requires service,
and obviates the need to return the entire amplifier in cases
where one channel is inoperative.
Accessories for special applications include the input
bridging circuit board for monophonic use; a panel for stan­
dard 19" rack mounting; and an alternative power
transformer for international A C line voltages.
Through advanced engineering geared to the audio per­
fectionist, and an efficient no-frills approach, Hafler is mak­
ing high technology high fidelity affordable.
C O N T E N T S
Page 3 AC Line Connections for Overseas Use
4 Kit Parts List
6 Schematic Diagram
10 Component Value Listing
11 Pictorial Diagram
2
12
13
14
15
Insert