The Quad 306
is a two channel power amplifier primarily intended for use in high quality
sound reproducing systems. The amplifier is usually used wit a Quad control
unit though other signal sources can readily be accommodated.
The
amplifier uses a current dumping output circuit
a Quad invention which eliminates many of the problems associated with
transistor amplifiers, and covered by patents in several countries. In a
current dumping amplifier there is in effect both a low powered very high
quality amplifier and a high powered heavy duty amplifier. The low power
amplifier controls the the loudspeakers at all times, calling upon the high
power section to provide most of the muscle. The small amplifier is so arranged
- it carries an error signal - that provided the larger power transistors (the
dumpers) get within the trget area of the required output current it will fill
in the remainder accurately and completely. The reproduced quality is solely
dependent on the small amplifier which because of its low power can be made
very good indeed.
Problems of
crossover, crossover distortion, quiescent current adjustment, thermal
tracking, transistor matching, all disappear. There are no internal adjustments
or alignments and the choice of power transistor types is less restrictive.
Amplifier
protection
The
amplifier is protected by a resettable trip which interrupts the incoming AC
supply if the amplifier is grossly overdriven for a period of time. To restore
operation simply press the red reset button on the back panel. The amplifier is
thus fully protected against gross overload, short-circuited output etc. But
not necessarily against seriously inadequate ventilation.
Input
Connections
Signal input
is via phono sockets, clearly marked L and R. if the amplifier is used with a
Quad 33/34/44 control unit with a DIN output socket, you wiull need a
4-pin-DIN-to-2-phono-plugs load.
Loudspeakers
Connections
The Quad 306
is fitted with standard 4 mm sockets and two red and black plugs are packed
with the unit. The amplifier is unconditionally stable and may be used with any
type of speaker cable.
The Quad 306
is entirely compatible with the ESL-63 loudspeaker but should not be used with
the earlier model which could easily be damaged.
Specifications
Power
Output: 50 watts per channel at 8 ohms
Distortion
(continuous sine wave into 8 Ω resistive load):
20 Hz (any
level up to 50 watts) : less than 0,01%
1 kHz (any
level up to 50 watts) : less than 0,01%
20 kHz (any
level up to 50 watts) : less than 0,03%
Output
Internal
Inpedance
and offset: 1,5 µH in series with 0,05 Ω . Offset tipically 7 mV
Frequency
Response:
-0,25 dB at
20 Hz to 20 kHz
-1,0 dB at
13 Hz to 40 kHz
Power
Response: -0,25 dB at 20 Hz to 20 kHz
Signal
Input Level: 0,375 volts for 50 watts
into 8 Ω
Signal Input
Overload: Instantaneous recovery up to 15 dB overload
Crosstalk
(input loaded by 1 k Ω):
100 dB at
100 Hz
85 dB at 1
kHz
65 dB at 10
kHz
Hum and
Noise: -105 dB (unweighted)
Stereo
Separation: 85 dB at 1 kHz
AC
Input: 110 - 120 V; 220 - 240 V,
Power
Consumption: 30 - 250 watts, depending on signal level
Dimensions
(W x H x D): 321 x 64 x 207 mm