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KRAMER ELECTRONICS LTD.
1.
INTRODUCTION
Congratulations on your purchase of this Kramer Electronics amplifier. Since 1981 Kramer has been dedicated
to the development and manufacture of high quality video/audio equipment. The Kramer line has become an
integral part of many of the best production and presentation facilities around the world. In recent years, Kramer
has redesigned and upgraded most of the line, making the best even better. Kramer’s line of professional
video/audio electronics is one of the most versatile and complete available, and is a true leader in terms of
quality, workmanship, price/performance ratio and innovation. In addition to the Kramer line of high quality
amplifiers, such as the one you have just purchased, Kramer also offers a full line of high quality switchers,
processors, interfaces, controllers and computer-related products. This manual includes configuration, operation
and option information for the following products from the Kramer VM-3 line of distribution amplifiers. All
these amplifiers are similar in operation and features:
VM-3S
/
VM-3Sxl
- 1:3 Audio/Video Distributor
VM-3V / VM-3Vxl
- 1:3 Video Distributor
The
xl
versions have a larger video bandwidth and include an external termination switch, so when you use a
“T” connector on the input, the incoming signal may be routed to another video user (looping).
1.1 A Word On Distribution Amplifiers
Distribution amplifiers are used to distribute one source to several acceptors for simultaneous recording or
monitoring of one source, with no discernible signal degradation. They vary in the number of inputs, looping
capability, programming capability, number of outputs, operating format, bandwidth and input/output coupling.
A good quality distribution amplifier amplifies the incoming signal, pre-compensates the signal for potential
losses (resulting from the use of long cables, noisy source, etc.) and generates several identical buffered and
amplified outputs. Often, a signal processor is inserted between the source and the distribution amplifier for
correction and fine-tuning of the source signal before multiplication, so that all copies are corrected in the same
way. The front panels of these Kramer amplifiers are designed to be simple to operate.
1.2 Factors Affecting Quality of Results
There are many factors affecting the quality of results when signals are transmitted from a source to an acceptor:
Connection cables
- Low quality cables are susceptible to interference; they degrade signal quality due to poor
matching and cause elevated noise levels. They should therefore be of the best quality.
Sockets and connectors of the sources and acceptors
- So often ignored, they should be of highest quality,
since "Zero Ohm" connection resistance is the objective. Sockets and connectors also must match the required
impedance (75 ohms in video). Cheap, low quality connectors tend to rust, thus causing breaks in the signal
path.
Amplifying circuitry
- Must have quality performance when the desired end result is high linearity, low
distortion and low noise operation.
Distance between sources and acceptors
- Plays a major role in the final result. For long distances (over 15
meters) between sources and acceptors, special measures should be taken in order to avoid cable losses. These
include using higher quality cables or adding line amplifiers.
Interference from neighboring electrical appliances
- These can have an adverse effect on signal quality.
Balanced audio lines are less prone to interference, but unbalanced audio should be installed far from any mains
power cables, electric motors, transmitters, etc. even when the cables are shielded.
