Hafler Stereo Amplifier SE240 User Manual

OWNER’S MANUAL  
HAFLER SE240  
HAFLER SE240  
POWER AMPLIFIER  
A Division of Rockford Corporation  
613 South Rockford Drive  
Tempe, Arizona 85281  
602  
-
967  
-
3565  
 
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.  
 
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.  
2
 
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  
3
 
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.  
5
 
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-  
 
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.  
7
 
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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