Hum and Noise
Phono:
Better than 71 dB below 10 millivolt
input from 20 Hz to 20 kHz
Flat:
Better than 64 dB below 10 millivolt
input from 20 Hz to 20 kHz
Operating Voltage
M64:
120 volts ± 10%, 50/60 Hz or 30 volts
± 20% dc. Listed by Underwriters’
Laboratories, Inc. (Applies to Model
M64).
M64-2E:
240 volts ± 10%, 50/60 Hz or 30 volts
± 20% dc
Battery Operation
The M64 and M64-2E may be powered by three
Eveready 216 Batteries in series or equivalent
power source connected to 30 V.D.C. jacks. Battery
life is over 100 hours. The Shure Model A67B
power supply, or power jacks on Shure’s Models
M63, M67, or M68, may be connected to the 30
V.D.C. jacks to power the M64 or M64-2E. These
jacks, which provide 29 Vdc (26 Vdc at 5 mA max.),
can also be used to power external equipment.
Input Impedance
Resistance is 50,000 ohms at 1 kHz
Capacitance is 350 pF
Output Impedance
High Level:
Less than 1000 ohms at 1 kHz (mini-
mum recommended load is 22,000
ohms)
Low Level:
600 ohms (any load on Low Level
output will not affect input clipping
level)
Dimensions
See Figure 2
Weight
794 grams (1¾ lb)
Power Consumption
5 watts
Temperature Range
Operating:
-7°C to 57°C (20°F to 135°F)
Storage:
-29°C to 71°C (-20°F to 160°F)
INSTALLATION
To reduce the risk of fire or electric shock
do not expose this appliance to rain or
The M64 and M64-2E Preamplifier may be mount-
ed to an amplifier chassis or cabinet by means of
screws passed through mounting slots at base of
M64 and M64-2E Preamplifier chassis. The Pream-
plifiers can be mounted in any position for normal
operation, but for best results, the Preamplifiers
should be located away from motors or other hum
producing power sources and away from intense
heat sources. Should hum be a problem in a given
system or installation, one or more of the power
plugs may be reversed to reduce hum. If the turn-
table has a grounding wire, this wire may be con-
nected to the “ground” screw on the Preamplifier
to reduce hum pickup.
WARNING
The use of the M64 and M64-2E Stereo
Preamplifier with power amplifiers of the
transformerless (ac-dc) type may result in a
shock hazard. A suitable power line isola-
tion transformer should be used with such
equipment.
Connections:
OPERATION
a. Set selector switch to the desired function.
This automatically selects the proper equali-
zation (frequency response) for both channels.
b. For the equalized Phono (RIAA) or Tape (NAB)
position, connect the signal leads from the
phono cartridge or tape head to the jacks
marked “Channel 1 Input” and “Channel 2
I n p u t . ” * F o r t h e F l a t p o s i t i o n u s i n g t w o
separate high-impedance microphones, con-
nect the cable from one high-impedance mi-
crophone to jack marked “Channel 1 Input.”
The cable from the other high-impedance
microphone should be connected to the jack
marked “Channel 2 Input.” For single high-
impedance microphone applications connect
to either Channel 1 or Channel 2. NOTE:
If low-impedance microphones are to be used,
a suitable input transformer such as the Shure
Model A95 Series should be used. Attention
must be given to information contained in the
data sheets of the phono cartridges, tape
heads, or microphones regarding their con-
nections, phasing and grounding.
c. Connect Ch. 1 and Ch. 2 (High Level or Low
Level) output jacks to the corresponding input
jacks of the power amplifier, preamplifier,
tape recorder or mixer.† If it is found neces-
sary to ground the M64 or M64-2E Preamplifier
chassis, ground connection may be made
* The Flat position may be used for high-impedance
microphones, or for phono cartridge or tape head
buffering applications in which the output of the
M64 or M64-2E is connected to an equalized am-
plifier input.
† The High Level outputs may be connected to
high-level auxiliary inputs, and the Low Level
outputs may be connected to low-level micro-
phone inputs (or equalized phono or tape head
inputs in buffering applications).
