Ampex 351 - Page 11

Controls
Tape Motion
Record Control
Tape Speed
Equalization
Reel Size
Record Inputs
Input
MICROPHONE
Reproduce Output
Head Housing
2-3
Monitoring
(aural and visual)
BAL BRIDGE
UNBAL BRIDGE
The signal on the tape can be monitored while the equipment is
recording. Two phone jacks are available to allow monitoring the
record input signal, or the output signal from the reproduce head.
A switch provides a means for making direct comparison between
the original program and the recorded program. The same switch
transfers a 4 inch vu meter for level comparison and visual
monitoring. The vu meter also is used to indicate bias and erase
current.
Tape speed can be changed by the TAPE SPEED switch. LOW or
HIGH positions are used to select drive motor windings.
An EQUALIZATION switch on the face of the electronic assembly
provides a means for selecting LOW or HIGH speed equalization
appropriate to the tape speed used.
Input Impedance
150 and 250 ohms nominal
(transformer can be strapped
for 30-50 ohms nominal.)
200K ohms
100K ohms
A REEL SIZE toggle switch on the tape transport makes possible
selection of the proper tape tensioning for the NAB IOV2 inch
diameter reel or the EIA 5 inch and 7 inch reels.
Minimum Input Signal that
will produce Operating Level
(1% tape characteristic
distortion)
200 microvolts
— 10 dbm
— 10 dbm
89-0144
Issue A
All tape motion is controlled by four pushbuttons, PLAY, STOP,
FAST FORWARD and REWIND.
A separate RECORD button on the face of the electronic assembly,
when pressed, energizes the record relay which drops out when
the STOP button is pressed. The stereophonic function (two track)
is controlled by pressing the RECORD buttons on both electronic
assemblies simultaneously. In two track operation, for consistency,
the master electronic assembly is usually connected to the upper
track in the head assembly so that, when the RECORD button
on the master (only) is pressed, recording takes place on the
upper track.
Zero indication on the v-u meter corresponds to +8 dbm (±1 db).
Sufficient gain and power handling capabilities exist to feed a
+14 vu line output into 600 ohms balanced or unbalanced. The
center tap of the output transformer can be strapped to ground
for balanced output. Plus 4 vu also can be obtained by strapping.
(See INSTALLATION).
The erase, record, and reproduce heads are contained in a single
head housing (See SECTION 6 on HEAD ASSEMBLIES).
The INPUT TRANSFER SWITCH provides a means for selecting
three different types of inputs: