Eela Audio EA815/2 Telephone hybrid
SYSTEM DESCRIPTION
The design goal for
EA815/2
was to produce a telephone hybrid with the best results and the
easiest operation. There is only ONE operator control; the
ON
switch to connect the PTT-line to
the hybrid instead of a telephone. The function can be remote controlled.
The power supply is a wide range “universal” adapter suitable for 100 to 240 Volts, 50/60 Hz and
comes with Euro, UK and US/Japan style wall plugs. Please note that these power supplies will
not work with older hybrids nor will the previous transformer adapters work with the new units.
The hybrid itself is composed around two transformers with a
PRESET BALANCE NETWORK
.
This preset network needs to be trimmed only at installation for best balance on an average line.
Practice has shown, that the connection to the first exchange is determining for the setting and in
most cases this is always the same line.
The best results can be obtained when a
DIRECT
telephone line is used, not routed via a house
telephone system.
To achieve the best damping of the send signal in the receive signal, this hybrid employs
VOICE
CONTROL
in combination with the preset balance.
The following processing is done:
The
SEND
signal is bandfiltered and limited, so not to spoil the damping by too much level and out
of band signals.
The
RECEIVE
signal has:
*
VOICE CONTROL
of the gain by the
SEND
signal. As soon as the studio starts talking,
the gain of the receive chain is reduced to lower the crosstalk over the hybrid. By this
action, the direct signal of the microphone is not spoiled by the crosstalk from the hybrid
and so gives a cleaner result.
*
Also some filtering is employed to reduce out of band signals like hum, dailing pulses etc.
GAINS
for
SEND
and
RECEIVE
are adjustable through the frontpanel.
