Electrocompaniet EC4 User Manual
EC4R BALANCED LINE PREAMPLIFIER
Owner’s Manual
WARNING: To reduce risk of fire or electric shock, do not expose
this appliance to rain or moisture. Verify line voltage before use.
Do not remove cover. No user serviceable parts inside. Refer servicing to
qualified service personnel. The warranty in void if the product is tampered with by non authorised personnel. Use only authorised
Electrocompaniet service station.
Welcome to the world of Electrocompaniet
We sincerely thank you for selecting an amplifier from Electrocompaniet. We hope you
will enjoy years of listening pleasure and true high end musical performance from your
audio system. Kindly read this owners manual to familiarise yourself with the set before
operation.
The Electrocompaniet Story
Electrocompaniet was founded in 1973 in Oslo, Norway, to manufacture an amplifier
designed by Per Abrahamsen. The design were based upon a new approach to transistor amplifier design developed by Dr. Matti Otala and Jan Lohstro.
It had long been recognised that transistor amplifiers had a characteristic sound that
many audiophiles and music lovers found unnatural.
Dr. Otala and Mr. Lohstro analysed transistor amplifiers to determine what actually
created the “transistor sound” in general transistorised designs. The results of their
innovative design work were incorporated in the first Electrocompaniet design, the
legendary 25 watt amplifier.
This product were the first commercial transistor amplifier to use this new design
approach, and the amplifier was immediately recognised as dramatically more musical
sounding than any other transistor amplifier. The same design philosophy, has been
constantly updated by additional research and development. This philosophy for m the
basis of all the current Electrocompaniet Ampliwire and Preampliwire Dual Mono
Balanced designs.
Electrocompaniet have always given extensive listening test of all it’s designs the
highest priority. Every product designed by our engineers must meet the varied and
exacting standards of the listening panel, carefully selected to represent a cross section
of musical taste and experience. Electrocompaniet designs go back and for th between
the design laboratory and the listening panel until both engineers and listeners are
completely satisfied, and ensured the that the design has met it’s technical and sonic
objectives.
All Electrocompaniet products are handmade by highly skilled technicians, and
extensively tested for maximum performance and reliability.
Final adjustments are made only after an extended period of operation to insure the
best possible performance under conditions similar to those of actual use.
Electrocompaniet Ampliwire and Preampliwire are sold in more than 25 countries ,
providing the ultimate listening pleasure to dedicated music lovers wor ld-wide.
The design features of Preampliwire EC4R
After the Electrocompaniet 25 watt amplifier had established a new standard for transistor amplifiers, research was undertaken to find ways to make the amplifier even better,
and to extend its highly musical sound quality to more powerful amplifier designs. The
engineers at Electrocompaniet were not satisfied by only reducing the commonly
recognised types of distortion to low levels. They recognised that distortion appears in
many forms, and that distortion was still audible in listening tests even when
conventional categories of distortion were at astonishingly low levels.
Traditionally, designers increased feedback to make a larger por tion of the output signal
control the amplifiers response. Our listening tests showed us that simply applying
more feedback was not the answer. In fact, as one kind of distortion went down, other
parameters would be adversely affected, leading to an overall degradation of sound
quality. We knew that the other conventional design approach of eliminating feedback
completely was not the answer either, because this would cause high distortion levels,
and as a result would produce a “woolly” sound.
The answer to the dilemma was found in a novel approach to feedback theory. We
developed a feedback concept that allowed local feedback to be applied around individual stages of the amplifier circuit. This approach allowed us to avoid the sonic
disadvantages of overall feedback from output to input. The concept was further
developed to reduce phase- and interphase distortion between stages of the amplifier
as well. We were able to concentrate the loop feedback on the stages of the amplifier
where it resulted in audible improvement.
Stability margins were also expanded because feedback no longer affected the frequency response. The use of this concept of individual gain blocks - complex in design
but simple in function - allowed us to reduce distortion to minute values in all the
products.
The various amplifier stages are divided into two separate sections or gain blocks. The
input block is a transconductance amplifier without overall feedback. This avoids large
output voltage being fed back to the input, and mixed with the minute input signal. The
output block is a transresistance amplifier with parallel feedback. This is done to prevent
higher frequencies than the feedback loop can handle, from entering the loop. An
approach like this will prevent Transient Inter modulation Distortion (TIM ) and Slewing
Induced Distortion (SID ), eliminating the need for an extremely wide bandwidth.
All stages work in Class A with an efficiency of less than 0,1%. The power supply of the
EC-4 R consists of a 50 VA toroidal transformers , and 8.000 micro farad reservoir
divided into eight 1000 micro farad capacitors, with separate regulator for each stage
and channel.
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