Shure m 65 owners manual

Page 1

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DATA SHEET

MODEL M65

Stereo Preamplifier

STEREO CONVERSION PREAMPLIFIER

GENERAL: The Shure M55 Stereo Conversion Preamplifier is
designed to furnish the voltage gain and equalixation necessary to
operate magnetic phono cartridges (such as the Shure. Dynatrc
Cartridges). and tape playback heads with standard audio ampli-
tiers. One ot the primary uses of the M65 is in the conversion of
stereo systems converting from ceramic cartridges to magnetic
cartridges. It can also be used without circuit modification as a
preamplifier tor microphones.

The M65 Stereo Preamplifier features a single rotary switch for
selection at either phono. tape. microphone or a special function.
The Phone function provides the Standard Equalization (RIAA) for
phone records. This function is ideally suited as an input for ampli<
tiers with a tlat response. The Special function provides a compen-
sated ceramic Equalization tor phone records. This function is
ideally suited for amplifiers normally used with Ceramic Phono
cartridges. The preamplifier has two stages of amplification in
each channel. providing STANDARD EQUALIZATION tor tape
(NARTB) and flat amplification tor microphones.

A hum control (R3) is provided and is pre-adiusted at the fac-
tory. If necessary. this control can be re-adiusted with a small
screwdriver for minimum hum. For optimum results the system should
use a 4pole motor.

The input impedance is 47.000 ohms for all switch positions. It
a higher impedance input is desired when used as a microphone
preamplifier. the 47.000 ohm input resistor (R. or R1) may be easily
removed automatically raising the input impedance to approximately
250.000 ohms. If any circuit change is made. the power should be
disconnected.

The output impedance is less than 5000 ohms in the "phono".
"tape and "special" functions allowing up to 75 test (22.8m) of
cable (30 ptd per toot [0.3m]) to be used without any high fre-
quency losses.

The preamplifier has dual input and output jacks which will no-
cept standard phone plugs. The preamplifier has its own power
supply and is operated from ll5-l25 volt 60 cycle line power.

CAUTION: The use of the M65 Stereo Preamplifier wlth
- power amplifiers of the transformerless (AC-

DCI type may be a shock hazard. A suitable

power line isolation transformer should be used.

NOMINAL SPECIFICATIONS:

Gain: Phono db
[5 millivolts input produces .76 volts output)
Special 45db
(S millivolts input produces .88 volts output)
Tape 40db
(5 millivolts input produces .50 volts output)
Microphone 63db
l2 millivolts input produces 2.8 volts output)
Frequency Response: i" 1.5:: of each functions nominal
characteristic from 25 c.p.s. to I5.000 c.p.s.

Equalization:

Phono: RIAA equalization [with additional treble boost of
approximately 3db at [0.000 c.p.s. to complement the high
frequency characteristic at most magnetic cartridges.)

Special: A Shure developed magnetic phono Equalization cir-
cuit specially designed for use with high impedance ampli-
tiers normally used with ceramic phone cartridges.

Tape: NARTB equalization.

Microphone: Flat response. i 3db from 20 c.p.s. to .000
c.p.s.

Input Impedance: 47,000 ohms (all functions).

Output Impedance: Low output impedance (less than 5000
ohms at l0.000 c.p.s. for phone. special and tape functions).

Copyright 1960. Shure Brothers, Inc.
2718166 (10-67)

Channel Separatio ~ 40db.

Channel Balance: i ldb at IOOO c.p.s.
Hum-Noise: 50db below rated output.
Tubes: Selected ECCB3/ IZAXI.
Rectifier: Selenium.

Finish: Nickel Plate chassis.

Overall Dimensions: Length 6%" (I74.6mm); Width 3%"
(I00.0mrn): Height 314" (95.2mm).

Power Consumption: 6 watts. IlS-IZS volts. 60 cycles.

INSTALLATION: The M65 Stereo Preamplifier may be
mounted on an amplifier chassis or cabinet by using screws pro-
vided. or using #4 machine screws and #4 nuts through the 4
corner mounting holes provided in the preamplifier base. Ampli-
tier can be mounted in any position for normal operation but should
be located away from motors and other hum radiating power
sources tor best performance.

APPLICATIONS:

a. Set selector switch to the desired function. Note that the
screwdriver slot of the shaft should align with the desired
function stamped on the chassis. This automatically select:
the proper equalization or frequency response for both
channels.

Is. For the Phone and Special positions. connect the signal
leads from the phone cartridge to the iaclrs marked "IN"
at "Channel A" and "Channel 3".

For the Tape position. connect the signal trorn the tape
head to the iacks marked "IN" at "Channel A" and
"Channel 3".

For in; Microphone position using two separate micro-
phones. connoct the cable from one microphone to the iack
marked "IN" at "Channel A". The cable from the other
microphone should connect to the incli marked "INI at
"Channel B. For single microphone application. connect to
either "Channel A or "Channel B".

Attention must be gIVen to the information contained in
the cartridge. tape head, or microphone data sheets regard-
ing their connections. phasing and grounding.

Prlnted In USA.

Page 2

c.

Canned \ha iaclts marked "OUT" of "Channel A" and
"Channel 3" To ihe corresponding inpui iacirs of ihe power
amplifier. lf if is found necessary in II;ri:und" {he M65
preamplifier chassis. a wire can be connected #0 one of fhe
screws holding {ha boflom plate to fhe chassis.

locaied near ihe rransiormer. For hum adiusimeni. insari
ihe screwdriver and rorale ihe control uniil ihe lowesr
audible level oi hum is obiained from {he speakers with no
program maierial in lhe sysfem and all conirol knobs sei in
iho maximum position.

d. Insarl- the M65 power line cord in a ll5-l25 volt 60 cycle
power ouilai. preferably one com-rolled by {he power am-
plifier's ON-OFF swiich. In some applicarions, a lower hum GUARANTEE: This Shure High Fidelify Componenf is guaran-
level may be obiained by reversing +he plug in the power reed lo be free from elecfrical and mechanical defects for a period
sucker. of one year from dare of shipmeni from faciary. provided all in-
sfruciions are complied with fully. In case of damage if is essenfial
e. Furihar reduction in hum may be obtained by a re-adiusi- ihai- you carefully repack rho unit and refum H '0 fha factory for
men! of he hum control [Rn]. The confrol is accessible for repair. Our guarameo is voided if {he basic assembly has been
screwdriver adiusimenis ihru a convenieni side opening opened or subiecfed lo unreasonably rough handling.
To 3+
loov c1 Ieoo PFD
RI7 9 .MIG
TAPE
. M 1
75 EG .7 '81 SPECIAL
R R R6 ' \ '° 25
5 I3
220 K ,00 K I MEG PHON0\\ R23 27 K
c, .05 O; .05 \ 150K ., .
CHANNEL 'A 50V (- (- y CHANNEL A
INPUT ' ~ ,6 , cs R l OUTPUT
0: ~47 2 _\|12-Eccesx. 7: 55mm 2| .
II a 1 mm R \ Ianxr 47o PFD '°°K I
II 8 I
.30V I
.25 v .00 K I
2. R1 Rs RIG l
[MEG lK [MEG lK l
l
I
l IT;
Ra Ra RIo RIs '
IMEC IK IMEGR IK |
I! I
.25V : .30V :
-:,'Escces/ '°°K "__ gzccea/ Clo : o
_ . oz .47 2 ,: I2Ax7 " 7"~ I2AX7 l u ,,
CHANNEL 3 l 6 ll 470PFD ) R24 CHANNEL B
INPUT 04 (.05 05 .05 .50K R OUTPUT
*6 RM 25
220 K I00 K R2 ' 4 27 K
I MEG 5 1 TAPE
RI. 0 SPEClAL
7O PHONO
7.5 MEG
TO 5+ 03 I300 PFD
IOOV

4 5 4.5
R21 Rae '

RESISTANCE IN cums:
K=Iooo
M5é= I.ooo,ooo
RESISTORS- V2 WATT, 1 K) as
EXCEPT R AND Rle,15%,
R29,IWATT.120% WIRE
7 v wouND POTENTIOMETER

:0: 5° OPS CAPACITANCE IN MICROFARADS
EXCEPT 07,09,09,AND cm
PFD= MICRC~MICRCFARAD

SWITCH FUNCTIONS
CHANNEL "A CHANNEL "5'
9-lO-PHON0- 4-I
9~II-7-sPECIAL-4-s-2
9-8- TAPE-4-3

MIC-4-7