Shure M64A Datasheet

The Shure Model M64A Stereo Preamplifier provides
the proper input and output impedances, voltage gain
and equalization necessary to operate magnetic phono
cartridges and tape playback heads with audio ampli-
fiers having no equalization. A low-noise and low-
distortion device, the M64A permits further signal pro-
cessing without appreciable degradation in signal-to-
noise ratio. In addition, the preamp can be used without
equalization for a microphone input or as a buffer
amplifier.
222
HARTREY AVENUE
S I I U m B
E v A N s T o N . ILLINOIS 60202-3696 U.S.A.
M E SOUND OF M E R)(XEYIONALl@ U K ) R L W I M
M I C R O P H O N E S
AND ELECTRONIC COMPONENTS
A
Typical Applications
Permits turntable to be used with PA mixers and
amplifiers without phono inputs
DATA SHEET
MODEL M64A
STEREO PREAMPLIFIER
L
Converting stereo record pickup systems from
ceramic to magnetic cartridges
Microphone preamplifier
Low-gain buffer amplifier (where long cable lengths
are extended to a preamp input)
The M64A has a single three-position slide switch for
selecting Phono, Tape or Flat frequency compensation.
The Phono position provides the standard RIAA
equalization for phonograph records. In this mode,
magnetic phono cartridges can operate into auxiliary
level inputs, inputs without RIAA equalization, or
ceramic phono cartridge inputs. The Tape position pro-
vides playback heads on tape recorders with standard
7-112 ips NARTB equalization. In the Flat position, the
M64A can be used as a flat-response microphone
preamplifier, or as a buffer (isolation) amplifier for
magnetic phono cartridges when long cable lengths or
switching systems are necessary between the turntable
and main equalized amplifier (note that the low-level
outputs should be used when operating the M64A as a
buffer amplifier).
The M64A's inputs and outputs are standard phono
pin jacks. Both high- and low-level outputs are provided,
so that the M64A can be connected to either high-level
auxiliary inputs or low-level microphone inputs (or
equalized phono or tape head inputs in buffering appli-
cations). A grounding screw is provided for hum pickup
reduction.
The M64A as supplied operates on 120 Vac, 50160 Hz.
An internal selector switch (qualified service personnel
only) permits operation from 240 Vac, 50160 Hz sources.
The unit can also be modified for balanced line output.
The M64A is listed by Underwriters Laboratories, Inc.
SPECIFICATIONS
Gain
(Measured at 1 kHz; input through 680 ohms; output
terminated in 47 kilohms)
Switch
High-Level Low-Level
Position Output
Output
Phono
+
34.5 dB +11 dB
Flat
+
27.5 dB
+
4 dB
Tape +37 dB
+
13.5 dB
Frequency Response
Phono:
+
2 dB of Standard RIAA curve from 40 Hz to
15 kHz
Flat: 20 Hz to 20 kHz, + 2 dB
Tape:
*
2 dB of 7-1/2 ips NARTB curve from 50 Hz to
15 kHz
60
$
Y2
0
40
-
30
20
20 100 1000
FREQUENCY IN HERTZ
10,000 20.000
TYPICAL FREQUENCY RESPONSE
FIGURE
1
Total Harmonic Distortion
Less than 1% with 2V output at 1 kHz in all switch
positions. Phono position only: less than l0/o at 30
Hz with 2V output.
Clipping Level (at 1 kHz)
Phono: 100 mV minimum
Flat: 250 mV minimum
Tape: 80 mV minimum
Channel Separation (at 1 kHz)
50 dB or more
Channel Balance (at 1 kHz)
Within 2 dB
Hum and Noise (20 Hz to 20 kHz)
Phono:
Better than 71 dB below 10 mV input
Flat: Better than 64 dB below 10 mV input
Copyright 1989. Shure Brothers Inc.
27A8086 (IF)