Manual

TELEPHONE HYBRID.
D&R's newest Telephone Hybrid is an interface between a standard telephone line and a mixing console. Its
purpose is to enable to record or broadcast a conversation between a caller and a presenter in an easy way.
Superb audio separation between in and outgoing signals are achieved by carefully designed internal
circuitry. It is a problem solver for changing two wire communication into a four wire system with separate in
and outputs.
Specs:
Output: balanced mic level -20db.
Input: Line level 0 dBu balanced.
R/C balance: fully adjustable
Separation: more than 30db.
USER MANUAL
The D&R telephone hybrid is intended to be used to create an easy connection between the telephone line
and studio equipment. Connection has to be made between telephone and the telephone line by way of the
hybrid. Connect the two wires of the telephone line to the tip and ground of the line input and connect the
telephone itself to the phone output on the tip and ground only.
Now the hybrid is interfaced (fully balanced) between your telephone and its connection to the outside world.
The hybrid is now capable of splitting the send and return signals. Connect the hybrid balanced audio input to
a (preferabie) balanced output of around +4dBu. This output has to be the mix of all signals except the signal
coming from the hybrid itself to avoid feedback. An Aux. output will do, or in broadcast mixers a modified
cleanfeed is the best.
SETTING UP PROCEDURE
Push the "to caller" switch and leave the "connect" switch in the up position Now dial the caller to whom you
want to talk. If this connection is made you connect the caller to the mixing console by pushing the connect
switch. Now listen by means of a pfl switch to the caller and adjust while talking the C and R balance so that
the outgoing signal (your talking) is best damped. Practically for a start is to put the C balance on number 7
and the R balance on 5 Carefully adjusting afterwards can be realised by slowly adjusting the R balance for
optimum damping. This can be left in this way for most of your calis, because only the line to you own
telephone station has to be balanced once. The damping will be around 22 to 26 dB.
The function of the "connect" switch is to connect the hybrid to the telephone line instead of the phone itself
(which is now switched off). The led indicates that a connection has been made.
The function "to caller” is there to disconnect the outgoing signal to the caller for private discussions
Manual page 3