OWNER’S MANUAL
HAFLER SE240
HAFLER SE240
POWER AMPLIFIER
A Division of Rockford Corporation
613 South Rockford Drive
Tempe, Arizona 85281
602
-
967
-
3565
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SPECIFICATIONS
Power Rating:
Less than 0.025% total harmonic distortion at any
power level up to 120 watts continuous average power
per channel into 8 ohms at any frequency between 20
Hz and 20 kHz with both channels driven,
Continuous Power Output:
Into 4 ohms, below -04% THD, 20 Hz-20 kHz,
per channel: 175 watts
IM Distortion (IHF):
Less than 0.005% from 1 watt to 120 watts, each
channel, into
8
ohms.
Typical THD at $0 watts into 8 ohms:
20 Hz: 0.004%
1
kHz: 0.004%
20 kHz: 0.02%
Frequency Response into 8 ohms:
-3 dB, 2 Hz to 200 kHz at 1 watt.
+0 dB, -0.5 dB, 4 Hz to 40 kHz at 120 watts.
Typical Channel Separation:
20 Hz: 80 dB
1
kHz: 75 dB
20 kHz: 60 dB
Signal to Noise Ratio:
Exceeds 100 dB referred to 120 watts into 8 ohms.
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Input Impedance:
47,000 ohms.
Input Sensitivity:
1.2 volts rms for 120 watts into 8 ohms.
Slew rate:
10 kHz, 60 volts peak to peak square wave: 45 v/us
Damping Factor:
300 to 1 kHz into 8 ohms.
200 to 10 kHz into 8 ohms.
Power consumption:
120 watts both channels into 8 ohms: 550 VA
Quiescent: 120 VA
Size:
5-1/4” high plus 1/2” feet, 17” wide. and 10-1/2” deep.
Net Weight:
27 Ibs.
Shipping Weight:
31 Ibs.
All specifications are subject to change without notice.
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INTRODUCTION
The Hafler SE-240 is a two channel audio amplifier which
has been engineered to meet high performance and
reliability standards while maintaining affordability.
The amplifier employs a sonically proven circuit topology
driving MOSFET output devices. These devices provide
exceptional reliability as a result of their inherent rugged-
ness and resistance to abusive operating conditions. Con-
sequently, the SE-240 is capable of delivering high current
into low impedance loads, and generally the amplifier will
not be damaged in the case of an accidental short circuit
at the output. The drive circuitry is a high performance
arrangement with a double differential JFET input. Quality
components are used in the design to ensure longevity
and, above all, sonic excellence.
INSTALLATION
Ventilation
Adequate air flow is important to the continuing reliability
of any amplifier. Cool air must be able to circulate freely
through the perforations in the cover and under the chas-
sis, and around the heat sinks. It is expected that the
amplifier will always be resting on its feet, which should be
on a hard enough surface that air flow underneath will not
be obstructed. If the amplifier is mounted in a rack, or
through a panel, the feet may be removed so long as
adequate ventilation is provided through the bottom open-
ings. It is normal for the cover and heat sinks to become
warm in use.
Location
If the amplifier is to be installed close to a record player,
you should first check its position for freedom from hum
pickup by the phono cartridge, as any large power trans-
former radiates a field which may induce hum. Although
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running them parallel to power wiring to reduce the
likelihood of hum pickup.
OUTPUT. The wires which connect the speakers to the
amplifier should be of sufficient size to preserve the SE-
240’s high damping factor. S
(zip cord) is satisfactory for up to 15 feet if your speakers
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are of 8 ohms or higher impedance. A heavier gauge (#16
or larger) wire should be used with 4 ohm speakers, or 8
ohm speakers at a greater distance. Special loudspeaker
cables which have adequate thickness to accommodate
long runs are usually available from audio dealers. The
SE-240’s red and black outputs accept standard b
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plug connectors, including the double ones with 3/4” spac-
ing. These are the most convenient to use if you will be
disconnecting the speakers occasionally. The terminals
will also clamp a spade lug, or a bare wire through the hole
in the center post. Be sure there are no frayed wire ends
which could touch adjacent terminals or the chassis. Tin
bare wire ends with solder to secure all strands.
PHASING. Consistent phase relationships are important
when connecting speakers in order to enable full bass
reproduction as well as mid-range and high frequency time
alignment. To be sure all the speakers in a system are
wired in phase to the amplifier, each ground or ‘-’ speaker
terminal should be connected to its black ground terminal
on the SE-240, and the speaker’s ‘+’ terminal to the cor-
responding red binding post. Speaker connecting cable
identifies one wire from the other by the color of the wire,
or by marking or coloring the insulation. NOTE: In the
special case of monophonic operation of the SE-240,
described later, different speaker connections are
employed.
GROUNDING. The black output terminals of the SE-240
are connected together internally and grounded to the
chassis, This facilitates the use of external devices which
use a common ground connection, such as some head-
phone junction boxes. You must be sure that the ground
or shield connection from such a device goes to a black
terminal on the SE-240. NOTE: No such connection may
be made when the SE-240 is connected for bridged mono
operation.
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Conventional Stereo Connections
It is best to make all connections with the SE-240 switched
off. Each of the stereo speakers connects to one horizon-
tal pair of red and black outputs, as identified left or right
on back of the SE-240. The input signals connect to the
corresponding input jacks, and the Mono/Stereo switch
should be set to Stereo.
Connections for Monophonic Operation
When you wish to drive a single loudspeaker with in-
creased power capability, the SE-240 can be operated in
a bridged mode which drives both channels with the same
signal and combines their output to deliver more than 350
watts into 8 ohms. In this arrangement, the speaker is
connected only to the two red output terminals. The left
red terminal is ‘+’, and the right red terminal is the ‘-’
connection.
No connections may be made to any black
terminal. Set the Mono/Stereo switch to Mono, and con-
nect the input signal to the left channel input only. Impor-
tant Note: Never use a speaker with an impedance of less
than 8 ohms when operating the SE-240 in the bridged
mode; the increased current output could damage the
amplifier.
LOUDSPEAKER SELECTION
AND PLACEMENT
Normal Stereo
The SE-240 is designed to deliver more than 120 watts of
audio power into an 8 ohm load. This will drive most
loudspeakers to a very loud volume level without clipping.
Note that speaker manufacturers often specify speaker
power requirements in two ways: nominal power (for
average volume levels), or maximum continuous power
(for momentary loud passages). Our 120 watt rating ap-
plies to maximum power levels. If your speaker im-
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pedance is less than 8 ohms, the SE-240 can deliver more
power into the lower impedance.
Sound reproduction accuracy is largely a measure of your
success in satisfying an illusion of the original. There are
few rules for speaker placement. The shape, furnishing
and acoustics of the room contribute as much as speaker
choice to the overall balance which you will find most
satisfying. In general, the two speakers are best placed
equally distant from the listener and from each other, either
along or just in front of a wall. It is best to have no
obstructions between the speaker and the listener. Some-
times raising the speakers is beneficial. Sound absorbing
materials, such as carpeting, draperies and upholstered
furniture help to reduce reflections, and thus improve the
sound illusion, but excessive absorption will deaden the
effect. Feel free to experiment with controls and furnishing
to achieve the overall balance which you like.
OPERATION
The pilot lamp in the power switch will glow whenever
power is applied in the SE-240. If it does not light, check
for a blown AC line fuse.
The SE-240 is equipped with a unique protection system
that constantly monitors the temperature of the output
devices and takes corrective action to prevent damage to
the amplifier as a result of excessive overheating. Under
most conditions, the SE-2403 heatsinks will dissipate the
heat required to maintain safe operating temperatures, and
the unit will play continuously. If the amplifier is driven at
high volumes into speakers with an impedance of less than
8 ohms, and/or there is inadequate ventilation, the
sinks could heat to a level that would cause the protection
circuitry to shut the unit off for a short time (normally less
than 1 minute) to prevent damage. The SE-240 will return
to normal operation, and if the overheating condition is still
present the cycle will repeat. In this case, check the
surroundings of the unit to ensure sufficient air flow around
the heatsinks and through the vent holes. Otherwise,
check the load impedance connected to the outputs to see
if it is far below 8 ohms.
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Fuses
The SE-240 is supplied with a 10 ampere Slo-Blo AC line
fuse and four power supply fuses. If one of these fails, it
is usually indicative of a fault which will require professional
service.
FACTORY SERVICE AND LIMITED WARRANTY
If you have any difficulties or questions concerning your
SE-240 amplifier, please call our Technical Service
Department weekdays, 8 a.m. to 4 p.m. Mountain Standard
time, at (602) 967-3565. Should you have any doubts
as to whether the amplifier is malfunctioning and re-
quires service, please call us before sending in for
repair.
The Hafler SE-240 is warranted for 3 years from date of
purchase, including parts, labor, and return shipping cost
from the factory to owner within the continental U.S.
It is the owner’s responsibility to pay shipping (preferably
UPS) to the factory; collect shipments will not be accepted.
Units under warranty should be accompanied by a copy of
the dated bill of sale. Use the original carton and all
packing material, and be sure to include a return address.
Also give a brief description of the difficulty, including
whether it is intermittent.
Warranties apply only to the original purchaser, and are
void if the amplifier has been modified without factory
authorization, or if parts have been substituted which, in
the factory’s opinion, are not suitable, or if the amplifier has
been physically or electrically abused or used for some
purpose for which it was not designed or intended.
This warranty gives you specific legal rights. You may also
have other rights which vary from state to state.
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