Dynaco QSA 300 Owners Manual

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This number must be men-
tioned in all communicalions
concerning (his equipment.

INSTRUCTIONS FOR

ASSEMBLY
OPERATION

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CONTENTS

Specifications ................... 2 Circuit Description .............. 14
Introduction . 3 Block Diagram ..... 14
Installation 3 Combining Channels 19
Connections . 3 Meter Operation 20
Operation ........ . 4 240 Volts Wiring .. 20
Assembly instructions .. 5 In Case of DiHicuIty . 20
Mechanical Assembly .......... 6 Voltages ... 22
Wiring the Heat Sink Circuit Board Layouts ...... ... 22
and P043 ,,,,,,,,,,,,,, 9 Service Policy and Limited Warranty 23
Wltlng the Chassis , 15 Kit Parts List .................... 24
Final Assembly .. . 16
fichematic Diagram .. iZ Pictorial Diagram ................ insert
Component Values .............. 13 MC<3 Meter Assembly instructions. . insert
SPECIFICATIONS

Rated 4-channel power output:

75 watts continuous average power per channel into 8 ohms (40
watts per channel into 16 ohms), 20 Hz-ZO kHz, at less than
0.25% total harmonic distortion. Distortion reduces at lower
levels. For optional conversion to Zrchannel use, see available
output power listed below.

Available 4-channel power output:
(See above for F.T.C. Power Ratings)
'20 Hz to 20 kHz, all channels driven:
75 watts continuous average per channel @ 8 ohms;
100 watts continuous average per channel @ 4 ohms;"
40 watts continuous average per channel @ 16 ohms.

Available 2 Low impedance mode connections:
80 watts continuous average per channel @ 8 ohms:
150 watts continuous average per channel @ 4 ohms;
200 watts continuous average per.- channel @ 2 obi-n3.

High impedance mode connections:
80 watts continuous average per channel @ 16 ohms;
150 watts continuous average per channel @ 8 ohms.
5 minutes sustained full power limit without a fart,

Power at clipping, single channel, 2500 Hz, less than 1°lo distortion:
90 watts @ 8 ohms,

130 watts @ 4 ohms.

45 watts @ 16 ohms:

Power at clipping, 2-channel mode, 2500 H1, less than 1"/a distortion:
LowZ mode: 95 watts @ 8 ohms; 160 watts @ 4 ohms;

240 wath @ 2 ohms.
Higer mode: 90 watts @ 16 ohms;160 watts @ 8 ohms

Intermodulation distortion:

Less than 0.25% at any power level up to 75 watts rms per chan-
nel into 8 ohms with any combination of test frequencies. Distor»
tion reduces at lower power levels.

Hall-power bandwidth:
37.5 watts per channel at less than 0.25% total harmonic distor-
tion from 5 Hz to 50 kHz into 8 ohms.

Frequency response:
+0, 71 dB, 10 H1740 kHz @ 1 wattinto 8 ohms
20.5 dB, 20 Hz-2O kHz @ 75 watts into 8 ohms

Hum and noise:
Greater than 95 dB below rated output, full spectrum.

Input:
35,000 ohm load: 10 volt for 75 watts @ 8 ohms.

Slewing rate:
7 volts per microsecond.

Damping factor:
Greater than 80 to 1 kHz into 8 ohms,
Greater than 50 to 10 kHz into 8 ohms:

Channel separation:
Greater than 70 dB by Il-IF standards:

Connectors:
InputS: phone jacks. Outputs: color coded 3rway binding posts
with standard 3/4" spacing.

Dimensions:
18%" wide, 14%" deep, 7%" high.

Weight:
Shipping weight: 581bs. Net weight: 52 lbs.

Power consumption:
120 v.a. quiescent; 10 amps maximum; 50/60 sz 120/240 VAC.

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ACCESSORY MC-3 METER KIT

DISASSEMBLY OF A FULLY ASSEMBLED Q5A-300
Skip this section if you are building the amplifier kit, and
have now completed step 18 on page 18 of the kit manual.

)Remove the wood panel on each side of the unit.
There are three black #6 Phillips head screws and
flat washers which affix each panel to a side.

)Remove the cover from the amplifier. There are 14
black Phillips head sheet metal screws holding it in
place.

)Slide out the dark plastic decorative strip and its
mating black fiber insert from the top section of the
front plate. Discard the fiber insert.

)Remove the front plate from the front panel. There
are six flat head screws and nuts holding it in place.
Discard three of the screws and nuts.

)Peel oil and discard the self-adhesive decorative
aluminum strip from the bottom of the front plate,
and along with it the small piece of blue plastic. A
thin knife or singleeedge razor blade slipped between
the decorative strip and the front plate will aid in its
removal.

)Turn the amplifier upside down, and remove the
three Phillips head sheet metal screws Whld1 affix the
front panel to the bottom of the chassis. Also loosen,
but do not remove, a screw in the corner hole of the
front panel at each end.

)Turn the unit right side up. Remove and discard the
cardboard light shield. Remove the two lamp sockets
from the front panel, and also the diode between
them. A flat head screw, 3 lockwasher, and a nut hold
each to the panel. N ext, unsolder the black wire of the
twisted pair of wires from the sockets on the right
side terminal strip T-3 lug #2 at the tin Also unsolder
the yellow wire from the twisted pair on the right side
diode block lug #2. Discard all the parts, except for
the #53 lamps (which may be kept as spares).

ASSEMBLING THE MCI-3 KIT
Begin here if you are continuing from step 18, page 18 of
the QSAVSOO manual.

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)Select the long metal lamp housing, the eight lamp
sockets, the eight #6 x 913 screws (largest screws but
shortest length), and eight #6 Km: nuts (lockwashers
attached). Position the housing so that the outer
flanges face you. Insert the screws from underneath
(outside), install each lamp socket over the screws
on the inside, and fasten with a nut on the inside,
Position the sockets on the angle shown, and tighten
the screws firmly.

)Prepare four 31/2 (9 cm) black wires, by removing
A" (.6 cm) of insulation from their ends. Connect
one end of the first wire to lamp socket lug #15 (S).
and the other end of this wire to socket lug #14 (S);
Connect one end of the second wire to socket lug #11
(S), and the other end to lug #10 (S). Connect one
end of the third wire to lug #7 (S), and the other end
to lug #6 (S). Connect one end of the fourth wire to
lug #3 (S), and the other end to lug #2 (S). Position
each wire against the lamp housing.

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,).Strip the insulation from a 3 (7.5 cm) black wire,

and cut the bare wire into three equal pieces. Connect
one end of the first bare wire to socket lug #13 (S),
and the other end to lug #12 (S). Connect one end
of the second bare wire to socket lug #9 (do not
solder), and the other end to lug #8 (S). Connect
one end of the third bare wire to socket lug #5 (S),
and the other end to lug #4 (S).

)Prepare a 4 (10 cm) black wire. Connect one end
to socket lug #9 (8-2). Position this wire as shown.
The other end will be connected later.

)Prepare an 11% (30 cm) blue wire. Connect one end
to socket lug #16 (S). Position this wire as shown.
The other end will be connected later.

)Prepare a 12% (32 cm) yellow wire. Connect one
end to socket lug #1 (S). Position this wire as shown.
The other end will be connected later.

)Select the eight #53 lamps, and install them in the
lamp sockets. They merely push in and turn.

Set this assembly aside, and place the QSA-300 in front of
you, front panel toward you. Tilt the front panel forward so
that its top edge touches the work surface.

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)Select the four meters, and fit them from the inside so
that the cross-slotted adjustment knob engages a mat.
ing hole near the top of the front panel.

)Select the lamp housing, and the two 3/4 #6 screws
and KB}? nuts. Invert the housing over the meters, so
that its flanges stay inside the front panel lip. Install -
the screws from the front (underneath) in the center
left and center right holes between meters "A and
B, and between meters C and D. Install the
nuts but do not tighten them beyond that necessary
to keep the meters snug-they should not rattle.

)1, U" shaped wires connect the terminals on each
meter, remove them.

)Select the eight solder lugs, and the eight #10 nuts
(without attached lockweshers). Install a solder lug
on each meter terminal, position the lugs as shown,
and secure each with a nut.

)Select the black wire from the lamp housing, and
connect the free end to solder lug #4.

)Select the blue wire from the lamp housing, and cone
meet the free end to the left T-3 lug #5 at the tip

- ( 8-2). A red transformer lead also connects here.

)Select the yellow wire from the lamp housing, and
connect the free end to the right T-3 lug #5 at the tip
( 8-2) , A red transformer lead also connects here.

)Prepare three 5 (12.5 cm) black wires. Connect one
end of the first wire to solder lug #8 (S) , and connect
the other end of this wire to lug #6. Connect one end
of the second wire to lug #6 (8-2), and the other end
to lug #4. Connect one end of the third wire to lug
#4 (3-3) , and the other end to lug #2.

)Prepare a 121/2 (32 cm) black wire. Connect one end
to solder lug #2 (8-2). Connect the other end to the
right T-3 lug #2 at the tip (8-2). A red-yellow trans-
former lead also connects here.