Yamaha PM-1000 Manual page 13

can be connected directly to the Sub In jacks, despite
the apparent impedance and level mismatch. The
explanation for this capability lies in the fact that most
hi-fi equipment, while rated at 10K-ohms output
impedance, has an actual output source impedance
of about 2K-ohms. Sub In, while rated at a nominal
input impedance of 600-ohms, has an actual termina-
tion of about 2.5K-ohms. Thus, the hi-fi equipment
will be loaded by Sub In, not severely, but enough
to drop the level by about 6dB. Considering that the
average hi-fi nominal output level is -16dB, a drop of
6dB brings the input to -22dB...very close to the
nominal -20dB sensitivity of Sub In.
For that hi-fi type equipment which will not function
satisfactorily when connected directly to Sub In, an
external line amplifier must be installed. Matching
transformers will not cure the problem because, to
match a high impedance source to a low impedance
input, somethinglike 10 to 14dB of voltage loss occurs,
and this would bring the hi-fi output level well below
the nominal sensitivity of Sub In.
PLAYBACK INPUTS
The four Playback Inputs (PB In) are designed to
accommodate the play output of a 4-channel profes-
sional tape machine. Alternately, two stereo machines,
two monaural and one stereo machine, or any com-
bination of sources that add up to no more than four
channels may be connected to PB In. Due to the same
factors explained under ""Submixer Inputs", hi-fi tape
machines cannot be connected directly to the PB In
jacks; external line amplifiers to match impedance and
level are required. PB In is available in each of the Master/
Monitor modules by latching the Direct/PB switch.
Tape playback may be used to feed recorded pro-
grams through the console outputs. In sound reinforce-
ment applications, this feature is handy for filling inter-
missions and breaks in the show. For studio applications,
PB In allows the operator to listen to a recording that
has just been made without having to alter the input
channels' controls.
PB In provides no equalization, filtering, or mixing
capability, so it is not suitable for playback of unmixed
recordings (except for reference). Raw, unmixed tapes
are better accommodated by the standard input chan-
nels. As explained under ''Submixer Inputs", the-20dBm
sensitivity of this input requires a 20dB or 24dB T-pad
(or H-pad) to be connected between the professional
machine's output and the PB In jacks. Locating the pad
at the console permits the higher signal level to flow
through the length of the transmission cable, reducing
the likelihood of hum and noise pick-up.
TALKBACK INPUT
The talkback jack on the front panel of the console
is provided for connection of a low impedance micro-
phone. This mic, usually mounted on a flexible goose-
neck, (available from your Yamaha dealer) is used by
the console operator to identify tape recordings, make
announcements, or for intercom with performers, light-
ing personnel, or other remote areas. When the console
is not located in the middle of the audience, the talk-
back input can be fitted with a Y-adapter. It will then
accept two mics, one for the console operator and one
TAREE 3
for his on-floor assistant. Both people can wear head- .
phones connected to the console's talkback output via
another Y-adapter. In this way, both can talk and listen
when the talkback button is pressed.
The talkback input is preamplified in the Talkback/
Oscillator module, which also has a level control and a
push-to-talk switch. The talkback preamp output can be
pushbutton-assigned to any combination of the four
program mixing buses, and it is simultaneously available
as a nominal +4dBm direct console output. The output
will drive 600-ohm or higher impedance headphones, or
a power amplifier. 8 ohm headphones will work, but
with some loss of fidelity. For best results with 8-ohm
headphones, and for additional listening volume, an
external headphone amplifier should be used.
MASTER IN & MASTER OUT
The Master In and Master Out jacks are unbalanced,
high impedance circuits designed for -20dB nominal
levels. As such, they are ideal for most hi-fi type equip-
.ment. For example, Master In and Master Out facilitate
the use of graphic equalizers and compressor/limiters.
Master Out also may be used to make tape recordings,
and/or to drive tape delay effects.
When no plugs are connected to the Master jacks,
the program mix flows between the jacks via an
internal jumper, then through the Direct side of the
Direct/Pb switch, and on through the Master Fader to
the console's Line and Monitor outputs. Inserting a
plug in a Master In jack interrupts the internal jumper.
Thus, when an equalizer or compressor/limiter is fed
by Master Out, processess the program mix, and
returns the processed audio to Master In, all audio
reaching the Master Fader flows through the remote
device.
Master Out is wired in a way that allows it to feed a
remote device without interrupting the flow of the
program mix to the console output; thus, a tape
recorder (such as the TEAC 3340 or Pioneer RT-1040)
can be fed from Master Out. Since the recorder feed
comes before the Master Faders, program fades will not
affect the level applied to the tape. The signal flow of
the program to the Master Faders is not affected
because, unlike Master In, inserting a plug in Master
Out does not break the internal jumper between
the jacks. If the recording is done in a studio situation,
as opposed to sound reinforcement, then the play
output of the recorder can be connected to Master In.
While recording, leave the Source/Tape switch on the
recorder in Source position; this allows the program
mix to be monitored in real time via the console's
Line or Monitor outputs. When the recording is
completed, simply switch the Source/Tape switch to
Tape mode; the tape playback can then be heard with-
out any adjustment of console controls.
To obtain a tape delay effect, feed a 3-head tape
recorder's input from Master Out, and return the
Play output (the Off Tape output) to the PM-1000
channel input(s); then the delayed audio can be
equalized with the channel equalizer and mixed back
into the program using the Channel Fader and the
Output Assign switches. Using Master Out, rather than
Echo Out to drive the tape delay has twin advantages: