Krell Industries S-150m User manual

THE LEADER IN AUDIO ENGINEERING
S–150m
Mono Power Amplifier
Instructions for Use
Owner’s Reference

Krell S-150m 1
Introduction
Thank you for your purchase of the Krell S-150m Mono Power
Amplifier. This configurable power amplifier has a discrete signal
path from input to output and employs a wide bandwidth design
with low negative feedback for sonic accuracy throughout the fre-
quency spectrum. All circuits up to the driver stage are balanced
and pure Class A.
Krell’s new surface mount technology (SMT) means that the S-
150m is a power amplifier with big power—150 Watts that does not
require big space. SMT allows individual circuit elements to be
placed very closely together. This shortens signal paths and allows
circuit elements to operate at the same temperature, resulting in
more accurate signal transfer and enhanced reliablilty.
The S-150m is a slim line design allowing five amplifiers to fit into
a space normally occupied by one. This owner’s reference con-
tains important information on the placement, installation, and
operation of the S-150m. Please read this information carefully. A
thorough understanding of these details will help ensure satisfacto-
ry operation and long life for your S-150m and related system
components.

Definition of Terms
Following are the definitions of key terms used in your owner’s ref-
erence manual.
Balanced
A symmetrical input or output circuit that has equal impedance
from both input terminals to a common ground reference point.
The industry standard for professional and sound recording instal-
lations, balanced connections have 6 dB more gain than single-
ended connections and allow the use of long interconnect cables.
Balanced connections are completely immune to induced noise
from the system or the environment.
Single-ended
A two-wire input or output circuit. Use care when using single-
ended connections as the ground connection is made last and
broken first. Turn the system off prior to making or breaking single-
ended connections. Single-ended connections are not recom-
mended for connections requiring long cable runs.
INPUT AND OUTPUT
CONNECTIONS
2Krell S-150m

Definition of Terms, continued
Off
The component is off when the rear panel button is in the down
position.
Stand-by Mode
A low power consumption status that keeps the audio circuits at idle.
Move the rear panel breaker switch to the on position and the power
status indicator illuminates in red. The component is now ready to
be switched to the operational mode. Krell recommends leaving the
component in the stand-by mode when it is not playing music.
Operational Mode
When the component is in stand-by mode, press the power button
on the front panel and the power status indicator will change to blue.
The component is in the operational mode and is ready to play
music.
12VDC Trigger
The S-150m may be turned on remotely via a 12 volt trigger.
Connect the 12V trigger output from a compatible device to the
12VDC trigger input. The S-150m will go from stand-by to opera-
tional mode when a 12 volts signal is applied. The S-150m will
return to Stand-by when the 12 volt signal is removed. The S-150m
can turn on other devices via 12 volt connection by connecting them
to the 12VDC trigger output. When the S-150m enters operational
mode, it will output 12VDC and remove it when returned to stand-by.
Input Selection
Put the input select switch in the posistion that matches the connec-
tion being used. Krell recommends the use of balanced/XLR when-
ever possible.
TECHNOLOGY
Krell S-150m 3
OPERATION

Definition of Terms, continued
AC POWER ON
For installations where the S-150m is not accessible or the 12V trig-
ger feature cannot be used, the S-150m may be set to power on
and off with the application or removal of AC power. This mode
bypasses the stand-by mode. The S-150m will go from power off to
full power when the AC outlet is energized. Conversely, the S-150m
will power off when power is removed rom the connected outlet.
Follow these steps to set the S-150m for AC power turn on:
1. Unplug the S-150m from the AC power outlet.
2. Use a T-15 Torx driver to remove the top cover screws (14)
3. On the left side of the amplifier, behind the faceplate, move the
jumper labeled POWER from the two pins labeled MANUAL to
the pins labeled AC. See Figure 1
BACKLIGHT ON/OFF
The S-150m power indicator may be disabled so that it is not illumi-
nated in stand-by (default is red) or operational mode (default is
blue).
Follow these steps to disable the S-150m power indicator:
1. Unplug the S-150m from the AC power outlet.
2. Use a T-15 Torx driver to remove the top cover screws (14)
3. On the left side of the amplifier, behind the faceplate, move the
jumper labeled BACKLIGHT from the two pins labeled ON to the
pins labeled OFF. See Figure 2
Krell S-150m 4
OPTIONAL
CONFIGURATIONS
Figure 1 AC Power On
Figure 2 AC Power On
Faceplate board shown with jumper installed to
AC power on.
Faceplate board shown with jumper installed to
BACKLIGHT OFF.

5Krell S-150m
Unpacking
Follow these steps to safely unpack the S-150m:
1. Open the shipping box and remove the top layer of foam. The
S-150m and the S-150m accessory kit containing the following
items are visible:
1 AC power cord
1 packet containing the Quick Setup Guide
and the warranty registration card
2. Grasp the underside of the amplifier and lift it straight out of
the packing box.
3. Place the amplifier in a safe location and remove the protective
plastic wrapping.
I f any of these items are not included please contact your authorized
Krell dealer.
Save all packing materials. If you must ship your S-150m in the future,
repack the unit in its original packaging to prevent shipping damage.
Notes

Krell S-150m 6
Placement
Before you install the S-150m into your system, review the follow-
ing guidelines to choose the location for the S-150m. This will facil-
itate a clean, trouble-free installation. The S-150m does not require
any type of special rack or cabinet for installation. For the dimen-
sions of the S-150m, see Specifications.
Place the S-150m on a firm, level surface, away from excessive
heat, humidity, or moisture. The S-150m requires at least 1 inch
(2.54 cm) of clearance on each side and at least two inches (5 cm)
of clearance above the component to provide adequate ventilation.
Installations inside cabinetry may need extra ventilation.
The S-150m is not hum-sensitive. Other components may be
placed on or around the S-150m (make sure ventilation grids
remain unobstructed).
Place the amplifier as close to the loudspeakers as possible and
keep loudspeaker cable lengths to a minimum. Loudspeaker cable
adds impedance to the load the amplifier must drive, regardless of
the cable’s gauge. All Krell amplifiers drive the lowest impedances
with ease, but long loudspeaker cables reduce the maximum
power that can be delivered to the loudspeakers.
The S-150m has superb regulation and does not require a dedicat-
ed AC circuit. Avoid connections through extension cords or multi-
ple AC adapters. High quality 15 amp grounded AC strips are
acceptable. High quality AC line conditioners or filters may be used
if they are grounded and meet or exceed the unit’s maximum
power consumption of 550 Watts.
The S-150m should be operated with the power cord
supplied and connected directly to the AC power outlet. Please
contact your authorized Krell dealer, distributor, or Krell before
using any devices designed to alter or stabilize the AC power for
the S-150m.
AC Power
Guidelines
Power Cord

Figure 3 The S-150 Front Panel
Figure 4 The S-150 rear panel
7Krell S-150m
Front Panel
1 Power Button
2 Power Indicator
Rear Panel
3 Input Switch
4 Balanced Analog Input
5 Single ended Analog Input
6 12 VDC Trigger In/Out
Power
7 Speaker Connectors
8 IEC Connector / Fuse
Holder

Front and Rear Panel Description
See Figures 3 and 4 on page 6 and 7
Krell S-150m 8
1 Power Button
Use this button to switch the S-150m between the stand-by and
the operational modes.
2 Stand-by Indicator
The red stand-by indicator illuminates when the S-150m is plugged
into a standard AC wall receptacle and the rear panel power but-
ton is pressed, indicating that the amplifier is in the stand-by mode
and ready to be switched to the operational mode. The indicator
turns blue when in operational mode
The S-150m back panel provides connections for all inputs and
outputs, power on/off, and additional remote connections.
3 Input Switch
Set this switch for the style of connection being used,
balanced/XLR or single-ended/RCA.
4 Balanced Analog Input
The S-150m is equipped with one balanced input via XLR connec-
tor.
5 Single-Ended Analog Inpus
The S-150m is equipped with one single-ended input via RCA con-
nector.
Consult the owner’s reference of the components used in a custom instal-
lation to take full advantage of the remote capability of the S-150m.

Front and Rear Panel Description, continued
9Krell S-150m
6. 12 Volt Trigger Input/Output.
Out.The output sends 12 VDC (12 V trigger) to other Krell compo-
nents and other devices that incorporate a 12 V trigger.
In.The input receives 12 VDC (12 V trigger) from other Krell com-
ponents and other devices that incorporate a 12 V trigger.
The 12 VDC output current is limited to 30 ma.
7 Speaker Connections
The S-150m is equipped with standard binding posts for each
amplifier channel. These connectors accept bare wire, pins,
banana plugs, or spade lugs. Use the red terminal for the positive
connection and the black terminal for the negative connection.
8 IEC Connector / Fuse Holder
The connector is for use with the provided IEC standard 20 amp
power cord.