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6. Adhere to all warnings and follow all operating instructions.
7. Warning: To reduce the risk of fire or electrical shock, do not expose this equipment to rain
or moisture.
There are no user serviceable parts inside. Refer
servicing to qualified personnel.
Model LDS2/150B
Owner’s Manual
Thank you so much for your decision to purchase one
of our superb Sherbourn amplifiers. W e take enormous pride in the design and build quality of all of our
products and we are confident that our product will
provide you with many years of enjoyable and troublefree service. Should you have any need to call upon
our services please feel free to contact us at the address shown at the end of this booklet; or, of course,
you can contact the dealership from which you purchased the product.
Full details of the warranty coverage provided by
Sherbourn T echnologies can be found at the end of
this booklet.
Safety Instructions
1. Important Safety Instructions! Please read
all the safety and operating instructions shown
in this manual before operating this equipment.
2. The lightening flash within an equilateral triangle
shown above is intended to alert you to the presence
of uninsulated ‘dangerous voltage’ within the product’s
enclosure that may be of sufficient magnitude to constitute an electric shock.
3. The exclamation point within an equilateral triangle
shown above is intended to alert you to the presence
of important operating and maintenance (servicing) instructions in the literature accompanying this appliance.
4. Sherbourn products are designed to comply with
international directives on the Restriction of Hazard-
ous Substances (RoHS) in electrical and
electronic equipment and the disposal of
W aste Electrical and Electronic Equipment (WEEE). The crossed wheelie bin
symbol indicates compliance and that the
products must be appropriately recycled
or processed in accordance with these
directives.
5. Please retain this manual in a safe place for future
reference about safety and operating matters.
8. Caution: To prevent electrical shock do not
use this (polarized) plug with an extension cord,
receptacle or other outlet unless the blades can
be fully inserted to prevent blade exposure.
9. For added protection for this product during a lightening storm or when it is left unattended and unused
for long periods of time, it is recommended that you
unplug the unit from the wall outlet. This will prevent
damage to the product due to lightening or power line
surges.
10. Do not use attachments not recommended in this
owner’s manual as they may cause hazards.
11. Locate the equipment for proper ventilation. For
example, the product should never be allowed to operate while positioned on a bed, rug, sofa or any such
surface where proper ventilation is not possible. Nor
should the unit be placed in a built-in installation such
as a cabinet or armoire, etc. in such a way as to impede the air flow. Always ensure adequate ventilation
openings - please see later comments regarding such
an installation.
12. Locate the product away from heat sources such
as stoves, heat registers, radiators or other appliances
including other amplifiers that produce heat.
13. Mount the equipment in a wall or cabinet only as
described in this owner’s manual.
14. Do not use the equipment near water; for example
near a bathtub, washbowl, kitchen sink, a wet basement, swimming pool, etc. This product is meant for
indoor use only .
15. Do not place the product on an unstable cart, stand
tripod, bracket or table. The equipment is heavy and
should it fall, it could cause serious injury to a person
and/or serious damage to the equipment.
Caution For Installation
1. Your Sherbourn amplifier can be placed on any
table or shelf. It can also be custom installed in a
rack, and/or in a piece of cabinetry or furniture of your
choice. It is however , important that if the amplifier is
going to be housed in an enclosed environment, that
you allow for adequate ventilation. Despite the adequately sized heatsinks built into the amplifier, it is still
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important that good ventilation be provided. Do not
install the amplifier directly above another heat generating component such as another amplifier without
adequate ventilation.
the LDS2/150B has designated that this will be the
primary system and so it is referred to as “A” and the
interrupter part of the LDS2/150B is referred to as
‘B’.
2. If your amplifier is going to be placed in an enclosed space such as an armoire, it is essential that
adequate ventilation be provided.
3. The dealership from which you purchased the product is an expert on custom installation procedures and
can provide invaluable advice to help you make an
aesthetically pleasing and trouble free installation.
Caution For Connections
1. Connect this equipment only to the type of AC
power source as marked on the unit. Always route
AC power cords so they are not likely to be walked
on, or tripped over, or where they may be pinched by
items placed on or against them. Always pay particular attention to cords at plugs and/or convenience receptacles, and at the point where they exit from the
product.
2. Do not defeat the inherent design features of the
polarized plug. Non-polarized line cord adapters will
defeat the safety provided by the polarized AC plug.
If the plug should fail to fit, contact your electrician to
replace your obsolete outlet. Do not defeat the safety
purpose of the grounding-type plug. If you use this
product in a country which only has two slotted receptacles in the house, you must use a three-pin adapter
plug to earth ground which is the “E” (earth pin) of the
power cord connected to this product.
3. Do not overload wall outlets, extension or integral
convenience receptacles, as this could result in a risk
of fire or shock.
Operating Voltage
The LDS2/150B amplifier is factory-set for 110V,
120V or 230V AC operation at either 50 or 60 Hz,
according to the country for which the unit was manufactured (230V in European Union countries, in compliance with CE regulations). The operating voltage
cannot be changed by the user and any attempt to do
so will void the warranty .
The LDS2/150B outputs a total of 2 x 50 watts into
an 8 ohm load and 2 x 75 watts into a 4 ohm load.
The amplifier will drive two pairs of 8 ohm speakers
or one pair of 4 ohm speakers. An embedded MPU
(Micro Processing Unit) ensures that the amplifier cannot be ’overdriven’, and the LDS (Load Detection
System) ensures that all speaker connections must be
good before the amplifier is connected to the speakers.
The LDS2/150B has an automatic internal sub-sonic
filter of -18dB per octave which rolls off very low frequency content (below 20 Hz) to avoid low frequency
saturation of a transformer volume control.
The unit can be set for a bridged/mono application in
which case the output will be 130 watts.
The LDS2/150B has a great many features all of which
are described in this manual.
Front Panel Description
The front panel has a number of important controls
with which you should familiarize yourself.
The blue LED will glow brightly when the unit is active
and will dim considerably whenever the unit is in its
‘sleep’ mode.
B Off Delay
Controls the priority ‘zone’ and enables you to set the
delay time for the ‘B’ zone from 0.3 minutes to a maximum of 5 minutes. Y ou need to set the front input selector to either ‘B’ or ‘Auto’ in order to use the ‘B Off
Delay’.
B On Level
Control allows you to set the sensitivity of the autoturn on circuit to be triggered by the ‘B’ input. The
range of this adjustment is from -86 dB below rated
output (indicated as ‘LO’ on the front panel) to -72
dB below rated output (indicated as ‘HI’ on the front
panel).
Care of the Product
Clean the product by dusting with a dry cloth. Do not
permit objects of any kind to be pushed and/or fall
into the product through the enclosure openings.
General Description
The LDS2/150B is an intuitive product that has been
designed primarily to facilitate seamless switching between a television and an installed music system. Since
it is assumed that an audio system is already in place,
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Input A/B/Auto
Switch allows you to select either ‘A ’ input only (always play signal from ‘A ’ input), or ‘B’ input only (always play signal from ‘B’ input) or Auto which allows
that whenever there is an input signal present at ‘B’
input it will override ‘A ’.
Concentric Volume Control
The volume control is a dual-shafted one which can
be used to set to your preferred listening levels on both
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‘A’ and ‘B’ inputs. However, should there be a need
to set ‘B’ to a different sensitivity from ‘A’ (for example, if your television at ‘B’ input plays at too low a
level) use a small flat-headed screw driver to set the
inner shaft of the control (located in the middle of the
volume control knob) to the desired setting.
Rear Panel Description
The following description identifies each of the main
controls/connection options and follows the rear panel
from left to right.
Input A
Offers both speaker level and line level inputs for the
non-priority zone. These inputs are paralleled inputs
to the LDS2/150B and only one input can be used at
a time. A ‘balanced’ input buffer is incorporated in the
speaker level input circuit; it will accept an output signal from either a ‘grounded’ or ‘floating’ music source.
Input B
This is the ‘priority’ zone and it is to these inputs that
you would normally connect the product over which
you seek to maintain control from the external amplifier. Similarly to input ‘A’, both ‘B’ inputs are paralleled inputs to the LDS2/150B amplifier, and again,
only one input can be used at a time. A ‘balanced’
input buffer is also employed in the speaker level input
circuit; it will accept an output signal from either a
‘grounded’ or a ‘floating’ music source.
Line Output (Buffered)
For use whenever a ‘daisy-chain’ installation and multiple LDS2/150B’ s are used. ‘Line Output’ outputs
the signal from ‘A ’ input if the LDS2/150B is playing
the ‘A ’ input, or outputs the signal from ‘B’ input when
the LDS2/150B is playing ‘B’ input.
Input B Triggers
These controls give you multiple options for your priority system and are used in connection with INPUT
B inputs.
Video In Jack
W orks only with the ’B’ input. T o use this trigger input, first set the trigger input selector to 12V/ V ideo
position. The LDS2/150B will turn on exclusively when
it sees a video signal present at this video input jack.
Music
W orks only with the ‘B’ inputs. With the LDS2/150B’s
‘B’ trigger switch in the ‘music’ position, it will automatically function once it receives a music signal and
will move into its standby mode whenever the signal is
absent for a period exceeding the delay time set by
the ‘B Off Delay’ control on the front panel.
12V / Video
W orks only with the ‘B’ inputs. With the LDS2/150B’s
‘B’ trigger switch in the ‘12V/Video’ position, the
LDS2/150B can be turned on from a ‘sleep’ state
whenever a 6V to 15V input signal appears at the 12V
input connector or a video signal at the ‘Video Input’
jack . 12V trigger and video trigger inputs are connected in parallel, only one of the inputs should be
used at a time.
12 Volt Connector
For 12V trigger input and output use the upper two
circuits marked ‘+IN-’ for 12V trigger input (to turn
on the LDS2/150B amplifier) and use the lower two
circuits marked ‘-Out+’ for trigger output. The input
accepts only a continuous DC trigger signal from 6V
minimum to 15V maximum for turning on the LDS2/
150B amplifier.
Fig. 1. Front panel view
Fig. 2. Rear panel view
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The trigger output is capable of delivering a continuous 12V, 30 mA of DC current to drive the downstream products (or multiple units of LDS2/150B
amplifiers) that may be associated with the LDS2/150B
amplifier .
MPU (Micro Processor Unit)
The MPU circuitry measures the impedance of the
speaker load that is intended to be connected. The
MPU only permits impedances above 3.5 ohms to
be connected.
Mode Switch
This control allows for a selection of ‘Stereo’
‘Mono’ or ‘Mono/Bridged’. In the latter mode, the
maximum output power is 150 watts. Please note
that ‘R-Channel’ input is accepted under the bridged
operation. Bridging is ONLY recommended when
8 Ohm speakers (or greater impedance) are used.
Input A Trigger
This control gives you the flexibility to have an input trigger for the ‘A’ zone. Like the priority ‘B’
zone, the sensitivity of the signal can be adjusted
from a low of –86 dB to a maximum of –72 dB of
the input signal.
NOTE: when playing the ‘A’ input; if the music
is discontinued for longer than 10 minutes, the
LDS2/150B will automatically enter its sleep
mode to cut down on energy consumption. The
front blue LED will then ‘dim’ to indicate that
the amplifier is in ‘Sleep’ and will only return to
its full luminance when it again receives a music signal.
LDS LED
This important control indicator is provided to indicate the correctness of your speaker connections
and to indicate that the intended speaker load is
not too great for the amplifier.
How to use the LDS and MPU
Test Functions
1. In order for the LDS2/150B to correctly carry out
its designated LDS and MPU test functions, you must
make all of your speaker connections with the master power switch in the ‘off’ position.
2. Only when you are satisfied that you have made
all the connections correctly should you turn the
power switch to its ‘on’ position. Once the switch
is on the ‘on’ position the LDS2/150B will then proceed with its diagnostic testing and the result will show
with the rear panel LED illuminating in either Green
or Orange.
3. If the LED illuminates in Green then everything
has been tested satisfactorily .
4. If the LED continues to flash in orange then there is
a problem with either a) the speaker connections or
b) the load impedance of the speakers.
5. T o determine if the problem is one of ‘connection’
you should listen to see if the synchronized test tone is
absent from any of your speakers. If you do not hear
the tone from one of the speakers, it is almost certainly that will be the one with the bad connection. You
should turn off the power and carefully reconnect the
speaker cables and then repeat (2) above.
Speakers 1 and 2
These are the speaker-out terminals that are connected with the cables from the loudspeakers.
Power Switch
Normally once you have switched on the amplifier the
signal sensing mode or the 12 volt trigger switch will
ensure that the amplifier goes into a ‘sleep/standby’
mode whenever it is not being directly used.
Protection Features
Y our LDS2/150B includes some important circuits that
are designed to protect the amplifier.
LDS (Load Detection System)
The LDS feature is a patent pending circuit that prevents ‘bad’ speaker connections to be made that could
cause the amplifier to ‘short’.
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6. If the same synchronized test tone can be heard
from all the speakers, then almost certainly it is because the impedance is too low . If you are trying to
use more than two pairs of speakers, it is suggested
that you remove one pair, turn off the amplifier and
then carry out another test by repeating step (2). If
this solves the problem, then it will indicate that the
load impedance with the two pairs of speakers
was too low . If the amplifier still does not work, then it
is suggested that you consult the speaker manufacturer to determine the exact impedance of the loudspeakers.
7. The LDS function refers to a ground potential for
measuring the speaker impedance. It does not measure the speaker under the bridge mode operation and
care should therefore be exercised in connecting the
speaker wires when the LDS2/150B is being used in
its bridged mode.
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Fig. 3. LDS2/150B Configured as an A-B Switcher .
For this configeration, set the front panel input selector to ‘auto’. When the Plazma TV is turned on, the
sound of TV will take over the speakers from the house music playing by the receiver or power amplifier . If the
Plazma TV has a line level output, use it instead of the speaker output (as shown). Use a set of audio cables to
connect the TV line outputs with the RCA jack line inputs under ‘Input B’ of the LDS2/150B.
Fig. 4. LDS2/150B configured as a Stereo Amplifier .
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Fig. 5. LDS2/150B Configured in Bridged Mode.
Use only the right channel inputs for bridged connection. Connect the “+” polarity of the speaker to the
“R+” speaker output, and the “-” polarity of the speaker to the “L+” speaker output.
Fig. 6. Location of bottom cover keyway slots used to mount the amplifier vertically against a wall with screws.
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Fig. 7 Optional Rack Panel assembly
Note 1 - Remove two M4 screws that fasten the front panel to the amplifier. Place the Rack Panel between the
front panel and the amplifier, and reinstall the screws. The front panel should be in front of the Rack Panel, and the
amplifier is in back of the Rack Panel.
Note 2 - Fasten the Alignment Bar (when two amplifiers are used) to the bottom cover of the amplifier using the two
screws already in place. This will hold the back of the amplifiers in alignment.
Note 3 - When only one amplifier is mounted to the Rack Panel, the second opening can be covered with a Cover
Plate that is not part of this kit.
Each Rack Mount Kit contains:
Item Qty Name T o Mount
(1) 1 Rack Panel
(2) 1 Alignment Bar
(3) 4 10-32 x 1" truss head screws Rack Panel
(4) 4 #10 shoulder washers Rack Panel
(5) 2 existing amplifier screws Alignment Bar
Separately available from Sherbourn:
(6) 1 Cover Plate with mounting screws
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Three Year Limited Warranty
Subject to the terms and conditions stated below , Sherbourn Technologies, Inc. (Sherbourn)
warrants to the original owner that this model
LDS2/150B shall be free from defects in workmanship or materials for a term of three (3)
years from its date of purchase from an Authorized Sherbourn Dealer. Transfer of this product by its original owner (the ‘Owner’) will automatically terminate this W arranty regardless
of when occurring.
In the event of any defect covered by this warranty ,
Sherbourn shall provide all parts, materials, and labor necessary to restore the Product to its original
specifications, and shall return the Product to its
owner at Sherbourn’s expense. In the alternative,
Sherbourn may at its sole option either replace the
Product without charge, or if its replacement is not
commercially practicable or repair or replacement
cannot be accomplished within a reasonable time,
Sherbourn may refund the purchase price of the
Product, subject where appropriate to reasonable
depreciation for actual use in accordance with applicable laws, in full satisfaction of its warranty obligations.
one other than Sherbourn or an Authorized Sherbourn
Service Facility; and Sherbourn shall have no liability
or obligation of any kind with respect to any of the
foregoing losses types of failures.
To obtain service under this Warranty, the Owner
must first obtain from Sherbourn a Return Authorization Number, and must then, at the owner’s expense (i) arrange for any necessary de-installation
of the Product, and (ii) deliver or ship the Product,
properly packaged and clearly identified with the
Return Authorization Number , prepaid, and insured,
to Sherbourn at the address shown below, or to an
Authorized Sherbourn Service Facility. In addition, the Owner must provide evidence that the
Product is at the time of delivery within the scope
of this W arranty , by including the ORIGINAL dated
sales receipt with the Product when submitted for
repair. Safeguard your original sales receipt, as it
may be required to validate Warranty coverage
The owner is solely responsible for payment of all
expenses for removing the Product from its installation, delivering it to Sherbourn or an Authorized
Sherbourn Service Facility , and reinstalling it following repair, as well as for any repairs made to
Products which are subject to the exclusions noted
above.
Sherbourn’s sole obligation under this warranty
shall be to repair or replace the product, or at its
option refund the purchase price, as provided for
hereinabove. Sherbourn does not warrant
against, nor shall it be liable for, any of the following: removal or installation charges, shipping
expenses to Sherbourn or its authorized service
facility, loss of use, property damage of any kind,
or other incidental or consequential damage or
losses of any kind.
Note: Some states do not allow exclusion or limitation of consequential damages, so the foregoing
exclusions may not apply to you.
This warranty does not cover any of the following:
(a) cabinetry , trim, or other appearance items (except where they are defective at the time of original sale and the Product is delivered for repair within
the first thirty days (30) thereafter): (b) failures arising from accident, catastrophe, misuse, neglect, or
failure to properly connect and operate the product in accordance with the accompanying instruction: (c) failures arising from improper installation
of the Product or incompatibility of other components in the system of which the Product is a part:
(d) failures of any kind in products (i) which have
been purchased from other than Authorized
Sherbourn dealers, or (ii) which evidence any tampering, alteration, or attempted servicing by any-
In order to learn the name and address of the nearest Authorized Sherbourn Service Facility, obtain
a Return Authorization Number and shipping instructions, or obtain answers to any other questions you may have concerning this Warranty , you
may telephone Sherbourn between the hours of 9:00
am and 5:00 pm Eastern Standard Time, Monday
through Friday at (978) 663-7385, or write to our
Service Department at Sherbourn Technologies,
Inc., 19-3A Sterling Road, North Billerica, MA
01862.
This warranty gives you specific legal rights, and
you may also have other rights which vary from
state to state.
If this product has been purchased outside of the
United States of America, you should contact your
local dealer or distributor to determine the warranty coverage provided in your country .
Sherbourn T echnologies, Inc.,19-3A Sterling Road,
North Billerica, MA 01862 T el (978) 663-7385
Fax (978) 663-7389 W eb www.sherbourn.com
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