Perreaux Prisma 350 User manual

Prisma 350
Stereo Power Amplifier
Owners Manual

2
Perreaux Industries Limited makes no warranty for the use of its products, other than those
expressly contained in the warranty detailed herein. The Company assumes no responsibility for
any errors which may appear in this document, reserves the ri ht to chan e products or
specifications detailed herein at any time without notice, and does not make any commitment to
update the information contained herein. No licenses to patents or other intellectual property of
Perreaux are ranted by the Company in connection with the sale of Perreaux products, expressly or
by implication.
mboob^ru
®
is a re istered trademark of Perreaux Industries Ltd.
Terms and product names in this document may be trademarks of others.

3
i
ii
i Introducing the Perreaux
350 Power Amplifier
Con ratulations on your Perreaux 350 purchase. To realise the full potential of
your unit you need to appreciate all aspects of its operation.
Before installin the 350 into your system, read the entire manual carefully.
Endeavour to und
erstand every detail by familiarisin yourself with the controls
and features as you read. You will find it easier to install usin the relevant
sections of this manual as a reference.
We have attempted to explain every feature and operational facet clear
ly and
concisely. In the event that somethin is still unclear to you, your Perreaux
dealer will be happy to assist you further.
Read this manual, install your unit correctly and realise the sonic si nificance of
your investment in Perreaux.
Perreaux prod
ucts are desi ned to provide the utmost in sonic realism and
electronic reliability with a functional yet ele ant appearance that reflects the
care and craftsmanship applied durin all sta es of construction.
Features at a
Glance
 Balanced and Unbalanced inputs
 Ru ed build quality
 Ultra-stiff power supply
 Soft-Start circuit
 Hybrid Class A/AB output sta es
 MOSFET output devices
 Hi h power output
 Dual bindin posts per channel
 Remote tri er input and output
 Multiple protection systems
 Advanced PCB desi n and earthin techniques
 Earth isolation switch
To maintain the consistently hi h quality that you expect from us, and we expect
from ourselves, Perreaux products are essentially handcrafted.
We maintain the human-link throu hout, from desi n and constructi
on, throu h
to the ultimate test, your music, your system, your ears.
Because we too listen to our products, we know that with your Perreaux you will
discover many more of the musical secrets we strive to reveal.
From all of us at Perreaux Industries Lim
ited, thank you for choosin the
Perreaux Prisma Series 350 power amplifier.

4
ii
iiii
ii Important Safety Instructions
Note:
All safety and operation instructions should be read carefully before the
350 is operated. Keep the Owners Manual in a safe place for fut
ure
reference.

The 350 should not be used near water, for example near a bathtub, kitchen
sink, in a wet basement, near a swimmin pool, etc.
 Mountin to a wall or ceilin should be via a heavy-duty bracket or shelf
desi ned for audio equipment use.
 The 350 should be situated away from heat sources such as radiators,
stoves, or other appliances that produce excessive amounts of heat.
 Always ensure the 350 heat sinks have adequate ventilation enablin air
circulation both above and below.
 DO NOT place the 350 directly onto carpeted surfaces.
 Avoid exposin the 350 to extremely hi h or low temperatures.
 The 350 should be connected to a mains power supply only of the type
described in the operatin instructions, or as marked on the rear of the unit.
 DO NOT disconnect the mains earth from the system.
 The mains power supply cord should be routed so that it is not likely to be
walked on or pinched by items placed on or a ainst it.
 The power cord of the 350 should be unplu ed from the mains outlet
when the unit is to be left unused for lon periods or when attemptin to
connect or disconnect cables and before cleanin your unit.
 Care should be taken so that objects and/or liquids do not accidentally fall
inside the 350.
 Please keep electrical equipment out of reach of children.
 Please unplu sensitive electronic equipment durin electrical storms.
 Please replace any fuse with the value and type specified.
 Avoid operatin the 350 with the cover removed.
 DO NOT bypass any fuse.

5
 DO NOT attempt to repair the 350. In the event of a problem, please
contact your Perreaux dealer.
 DO NOT operate this product in an explosive atmosphere.
Caution!
he 350 is an extremely high powered, convection cooled amplifier. he
finned outer heat sinks may become very hot when d
elivering high
volume levels –
to avoid injury; care should be taken not to touch the
heat sinks during operation.

6
iii
iiiiii
iii Table of Contents
i
ii
i Introducing the Perreaux 350 Power Amplifier ........................................................3
ii
iiii
ii Important Safety Instructions ........................................................................................
iii
iiiiii
iii Table of Contents ..............................................................................................................6
1
11
1 Unpacking and Placement..............................................................................................7
2
22
2 Instant Install......................................................................................................................9
3
33
3 Front Panel Functions................................................................................................... 11
Rear Panel Functions..................................................................................................... 12
5
55
5 Special Design Philosophies ........................................................................................ 16
6
66
6 Special Design Features................................................................................................ 18
7
77
7 Maximising System Potential ...................................................................................... 20
8
88
8 The Power MOSFET....................................................................................................... 22
9
99
9 Care and Maintainance................................................................................................ 25
10
1010
10 Warranty Information and Obtaining Service........................................................ 26
11
1111
11 Extended Warranty Registration Form.................................................................... 27
12
1212
12 Faultfinding Your System............................................................................................. 28
13
1313
13 Specifications................................................................................................................... 33
1
11
1 Physical Dimensions ...................................................................................................... 36
15
1515
15 Contact Details................................................................................................................ 37

7
Unpacking and Placement
The 350 is packa ed for maximum protection. Please care
fully read the
instructions below before proceedin to unpack the unit. Be extremely careful.
Unpacking
Procedure
 Inspect both ends of the cardboard box and open at the end without the
central staple by slittin the reinforced tape at either side.
 Fold back the flaps and tip the packa e on end and the inner box will
slide out.
 Lay the inner box down flat and upri ht, open it conventionally by
separatin the top tray from the bottom.
 The product can now be removed from the bottom packa in . This will
be easier if you have someone to help you by holdin the base of the
box.
 Alternately, the bottom tray and amplifier could be tipped upside down
and the bottom packa in removed. If opened in this manner, please
ensure that you turn the contents over a ain.
Note:
Be very careful to secure the unit if you are planning to flip the package
upside down.
 Remove the two white polystyrene protectors off either side of the
amplifier, leavin the black material coverin .
 Pull back the material and remove the protective black tissue from the
front panel.
The amplifier is now unpacked and ready for further installation.
Note:
Please retain all packaging material for future transport.
Box
Contents
1 x 350 Power amplifier
1 x 350 Product manual
1 x Detachable AC power cord
3 x Performance analysis charts
Placing
Your 350
The 350 should enerally be placed close to your preamplifier, keepin the
interconnect cablin short.
We stron ly recommend keepin the 350 on it’s own separate shelf to allow for
proper ventilation.

8
Ventilation
Requirements
The 350 is a hi h-powered amplifier. For optimal performance, the unit M UST
receive adequate ventilation.
 Please do not install in a sealed cabinet.
 Please do not stack products directly on top of the unit.
 Please do not cover the product with a cloth or similar.
 Please do not mount the 350 directly onto carpeted surfaces.
 As a “rule of thumb”, allow 80-100mm (3-4 inches) around all sides of
the product and mount the 350 on a flat surface, ensurin that the unit
has adequate access to free flowin air.
 In the event that the 350 is to be incorporated into custom cabinetry,
please refer to Chapter 14 “Physical Dimensions”.
Note:
Please take all necessary steps to ensure that the unit receives adequate
ventilation

9
2
22
2 Instant Install
If you are like us, the first thin you will want to do is to play your favourite
piece of music throu h your new 350. The followin instructions are written to
enable you to achieve this as quickly as possible. These are not comprehensive
instructions, but are desi ned to enable you to play music now!
Note:
Please take the time to read the 350 manual thoroughly as it incorporates
many features, which will enhance its operation.
Placement
The 350 is a hi h-power amplifier and best results wi
ll be achieved when placed
on a solid surface with adequate ventilation. DO NOT place on
a carpeted floor
or cover the amplifier!
Turn off associated components
This minimises the potential to dama e any other components when connectin
your 350 into the system.
Connect preamplifier to 350
Connect the output of your preamplifier to either the balanced (XLR) or un-
balanced (RCA
) inputs at the rear of the 350 and set the input confi uration
to le switch at the rear to the correct position.
Note:
ry to
keep all interconnect cables as far from loudspeaker cables as
possible and well away from all AC mains leads.
Connect speaker cables to the left and right speaker terminals
We recommend usin hi h quality connectors for your speaker cables, spade
lu s
are the preferable option as they combine a lar er surface area with the
possibility of a stron mechanical connection; however, hi h quality banana
terminals are also acceptable.
Note:
Be careful to maintain channel integrity, i.e. left to left, right to
right, and
phase integrity, positive (+) to positive (+), negative (-) to negative (-).
Switch on preamplifier
Turn on the preamplifier and set the volume to the minimum level. Select the
respective input to which your source component is connected.
Switch on 350
After checkin the supply volta e compatibility with the volta e ratin on the
350 rear panel, insert the power cord-
set supplied into the rear of the unit and
into the wall. Switch on the socket at the wall and power up the 350 usin the
switch on the rear panel.

10
Start your source component
Switch on the source component both at the wall and on its front panel. Ensure
you have some source material inserted and press play.
Increase the volume
Slowly increase the preamplifier volume co
ntrol to achieve a comfortable
listenin level.
CONGRATULATIONS!
Now that you have achieved your first objective, sit back, relax and please read
the rest of the manual at your own pace, in your favourite armchair, whilst
sippin a hot cup of coffee. Yo
u’ll find the whole experience much more
pleasurable whilst listenin to music.

11
3
33
3 Front Panel Functions
Power Indicator
The indicator li ht is an LED that shows the status of your 350 power amplifier.
Off
This indicates that the amplifier is either not connected to the mains supply
, or
the unit is in standby.
The unit not bein connected to the mains supply
could be due to the power
switch at the rear of the unit bein set to the OFF position,
or power not bein
supplied to the mains power cord (e. . unplu ed, switched OFF at the
wall
socket, tripped circuit breaker, etc.).
Standby occurs when the unit is connected to the mains supply with the power
switch bein set to ON and a master device,
connected via the remote tri er
input at the rear of the unit, is set to OFF.
To brin the unit out of standby the
master device needs to be set to ON.
For more information on the remote tri er, please refer to Chapter 4 “Rear
Panel Functions”.
Blue
When the LED is blue, the amplifier is ON and ready to be used.

12
4
44
4 Rear Panel Functions
Caution!
Please make all changes at minimum volume setting. Only increase the
volume after the connections have been made.
Serial Number
The serial number is unique to your 350. Please record this number and store it
in a safe place. For any service related enquiry, please be prepared to quote the
product serial number to Perreaux personnel or their service representative.
Input Voltage and Fuse Rating
Input Voltage
It is important that the 350 be operated from t
he correct AC mains volta e. This
unit is factory set for the volta e applicable to the ori inal country of
destination.
The 350 will operate satisfactorily within a volta e variation of up to ±5% of
that volta e at which the unit has been set.
If you req
uire the volta e settin to be altered, e. . relocation to another area,
city or country, or extraordinarily hi h or low volta es, please contact your
Perreaux dealer. Qualified service personnel can only perform this modification.
Caution!
Never attempt
to connect the unit to the incorrect voltage. Severe
damage can result from applying incorrect voltage to the unit.

13
Fuse Rating
The fuse ratin displayed here, refers to the ratin of the mains inlet fuse.
For more information on fuse ratin s, pleas
e refer to Chapter 13
“Specifications”.
Caution!
Never replace the fuses with any other ratings other than the one
specified.
AC Mains Input
An IEC-
standard mains input is provided at the rear of the unit. The AC cord set
is removable, allowin you to up rade to a cord set of your preference.
Caution!
Prior to connection to the AC mains, please check the voltage label on
the rear panel to ensure that your unit conforms to the power supply in
your area. Never attempt to connect the unit to the incor
rect voltage.
Severe damage can result from applying incorrect voltage to the unit.
Earth Lift Switch
This switch enables the user to isolate the internal si nal earth of the amplifier
from the mains earth and is useful if system hum is a problem. S
ettin this
switch DOWN connects the internal si nal earth to mains earth and is the normal
position. Settin to UP disconnects the si nal earth from the mains earth.
Note:
Activating this switch has no effect on chassis earth, maintaining the
connection to mains earth.
Mains Fuse
The 350 is equipped with a user serviceable AC mains fuse. In the event of fuse
failure, always replace with the same type and value fuse. Remember, fuses do
not usually blow without a reason. Any doubts about fuse failu
re should be
conveyed directly to your Perreaux dealer.
For more information on fuse ratin s, please refer to Chapter 13
“Specifications”.
Caution!
his is the ONLY user accessible fuse.
Never replace the fuses with any other ratings other than the one
specified on the rear panel.
Always ensure your 350 is disconnected from the mains supply before
attempting to change the mains fuse.
Remote trigger input and output
The remote tri er system is desi ned to switch on or off the 350 and any
connected per
ipherals. If the 350 is switched on or off via the remote input
tri er, any peripherals connected via the slave tri er output will also be
switched on or off.

14
Master rigger Input
The master tri er input (leftmost 3.5mm socket) is used to take the 35
0 in and
out of standby. The master tri er input is desi ned to accept a 3.5mm diameter
male plu . The volta e ratin is +5V to +12V DC level ON and 0V DC level
OFF.
The plu must follow the specifications as per the followin dia ram:
Slave rigger Output
A parallel slave tri er output (ri htmost 3.5mm socket)
is provided to switch on
or off any connected peripherals to the 350. The slave tri er output is desi ned
to accept a 3.5mm diameter male plu . The volta e ratin is +12V DC level ON
and 0V DC level OFF.
The plu must follow the specifications as per the dia ram below:
Power Switch
Set this switch ri ht (I
) to turn power ON. Mute relay circuitry is employed in
the 350 so output is muted momentarily after the power switch is actuated.
Set
the switch left (O
) to turn the unit off, at which time the outputs will be
disconnected.
Speaker Output Terminals
The 350 is equipped with two sets of output terminals per channel, to enable
easy hook-up for bi-wirin of loudspeakers or additiona
l loudspeakers. All
terminals are clearly marked and colour coded RED Positive (+) and BLACK
Ne ative (-
). This polarity must be observed when connectin loudspeakers, i.e.
positive terminal of the 350 to the positive terminal of the loudspeaker and
ne ative terminal of the 350 to the ne ative terminal of the loudspeaker.
Caution!
Never connect the amplifier’s output terminals to any device other than a
loudspeaker.
Please do not short circuit the amplifier’s output terminals.
Never connect the output of
one amplifier to the output terminals of
another amplifier.
Do not over-tighten the binding posts on your amplifier.
For more information, please refer to Chapter 7 “Maximisin System Potential”.

15
Balanced Inputs
Accepts a si nal from a preamplif
ier with balanced outputs via a hi h quality
XLR connector.
The use of ood quality balanced line cable into the balanced
input cause the input si nal to be relatively immune to noise and external effects
caused by the use of lon interconnect cables, hel
ps reduce hum loop noise and
aids in the cancellation of distortion products.
Refer to Chapter 13 “Specifications”, for detail on input sensitivity and
impedance.
Note:
Please set the input configuration switch to the appropriate setting.
The pin assi nments of the balanced XLR connectors are as follows:
Pin 1: Signal ground
Pin 2: Signal + (non-inverting)
Pin 3: Signal – (inverting)
Shield ground: Chassis ground
Note:
Please refer to the operating manuals of your balanced output line level
sou
rce to verify that the pin assignments of the output connectors
correspond to the 350 balanced inputs. In the event that they are not
compatible, the interconnecting cable will need to be altered to suit.
For more information re ardin balanced interconne
cts, please refer to Chapter 7
“Maximisin System Potential”.
Unbalanced Inputs
Accepts a standard sin le-
ended input pair (RCA) from preamplifiers with
sin le-
ended outputs. The connectors are hi h quality old plated sockets which
are hi hly conduc
tive, corrosion resistant, and provide less potential for
corrosion induced distortion. Inputs are clearly marked Left and Ri ht, indicated
by a black and red rin respectively. Care should be taken to maintain channel
inte rity.
Refer to Chapter 13 “Spe
cifications”, for detail on input sensitivity and
impedance.
Note:
Please set the input configuration switch to the appropriate setting.
Input Configuration Switch
This to le switch allows selection of either the balanced or unbalanced inputs.
Note:
Input leads should be connected to one type of input only, i.e. do not
connect to both the unbalanced and balanced inputs at one time.

16
5
55
5 Special Design Philosophies
Perreaux has been desi nin and manufacturin only the hi hest quality audio
co
mponentry for more than a quarter of a century. Technolo y has continued to
evolve rapidly over that time and our knowled e and application of desi n,
materials and manufacturin techniques has advanced in tandem with this.
Today’s Perreaux ran e comes c
loser to fulfillin our shared vision than at any
other time in the past.
To follow is a discussion on some of Perreaux desi n philosophies that have
been incorporated into the entire ran e.
Minimalist
Design
Leadin British architect, John Pawson, writes:
“The Minimum can be defined as the perfection that an object
achieves when it is no longer possible to improve it by subtraction.
This is the uality that an object has when every component, every
detail, and every junction has been reduced or condensed to the
essentials. It is the result of the omission of the inessentials”.
Perreaux has historically embraced the minimalist ethic from an audio desi n
perspective only. The concept of “less equatin to more” has been at the heart
of all Perreaux audio desi ns for more than a quarter of a century.
Minimalist Electronics
We wish to maximise the quality of your listenin pleasure by keepin the
componentry and si nal path as uncluttered, short and clean possible. All
components in the si nal path, even th
ose of the hi hest quality have an effect
on the si nal, thereby alterin the quality of the reproduction in some way. Our
aim is to recreate in its entirety, the ori inal performance by not addin or
subtractin anythin , irrespective of the source.
Minimalist User Interface
We carefully study the user interface and par down the number of buttons and
associated clutter leavin just the essential and no more. How temptin it has
been over the years to loose si ht of our core values as technolo y or trends
have made it possible. That is one of the reasons why our older products still
have such a hi h resale value today. The user interface has and always will
remain simple, free from adornments, clean and uncluttered.
Minimalist Aesthetics
Our products app
eal to those who seek the ultimate in audio exclusivity, namely
the perfect blend of “form and function”.

17
“Form and function” are both tou h masters. That is why our amplifier heat
sinks are not hidden, but instead feature prominently in all our d
esi ns. We
make no excuses for producin some of the most distinctive hi h-
end audio
products on the planet. We let “form and function” blend to ether in perfect
harmony. This surely is the essence of true minimalist utilisation.
Minimalism in a Wider Context
John Pawson writes:
“Clearly simplicity has dimensions to it that go beyond the purely
aesthetic: it can be seen as the reflection of some innate, inner
uality, or the pursuit of philosophical or literary insight into the
nature of harmony, reason, and truth”.

18
6
66
6 Special Design Features
Rugged Build
Quality
Mechanical stren th has been a hallmark of Perreaux products since the
company first started production back in 1974. The concept behind the physical
desi n and construction is that each struc
tural member should contribute to both
ri idity and performance.
Ultra Stiff
Power Supply
The 350 incorporates a massive custom desi ned, toroidal power transformer,
employin unusually heavy au e wire that reduces copper losses to a
minimum. An electro
static shield prevents AC line borne interference from
enterin the si nal path. The power supply filter capacitors, totalin 60,000µF
(30,000µF per channel), have exceptionally low inductance and internal
resistance. They char e and dischar e in respons
e to load demand far more
rapidly than conventional stora e capacitors and are capable of deliverin the
instantaneous current required by the output sta es, providin optimum dynamic
ran e and transient response. The wirin from the power supplies to the
output
boards is desi ned for unimpeded transmission of the required current and
volta e and utilizes heavy au e, tinned copper wire cables. Since power supply
leads radiate at si nal frequencies, all wirin is carefully loomed to minimise
this effect.
Hybrid Class
A/AB
The bi-
polar transistors used in the 350 are run in Class A mode. This avoids the
crossover notch distortion and the resultin odd-
order harmonics present, to
some de ree, in all other classes of operation. The devices used in the 350
output sta e are M OSFETs, which with hi h quiescent current circuitry, are run
in the equivalent of Class A to 10 watts. Beyond this point the output class is
technically Class AB (hence the hybrid nomenclature), but with a major
difference. The combinat
ion of M OSFET characteristics and their application in
this circuitry, result in crossover distortion so minimal that it is virtually non-
existent.
MOSFET
Output Stage
The 350 output sta e takes full advanta e of the unique qualities of M OSFET
devices and in many ways they are superior to bi-
polar transistors. A major
advanta e is their tendency to draw less current over a lar e section of the power
bandwidth as their temperature rises (Ne ative Temperature Coefficient), hence
self stabilisin thermally, whereas bi-
polar transistors draw more current as their
temperature rises (Positive Temperature Coefficient) and protection circuits
become mandatory to prevent thermal runaway and eventual self destruction.
MOSFETs have the ability to swin fully across
the amplifier’s internal DC
volta e and are therefore true "rail-to-
rail" devices. Usin MOSFETs
encoura es the hi hest performance from the balance of the internal amplifier
circuitry.

19
Multiple
Protection
Systems
The 350 is equipped with a number of
protection systems, isolated from all
si nal carryin circuits via opto-
couplers, to protect both itself and ancillary
equipment.
DC Offset Protection
This system senses if any direct current (DC) is present at the 350 output
terminals and disconnects the
output to avoid potential speaker dama e. DC
may be present due to ancillary equipment feedin DC into the input or an
amplifier fault.
Short-Circuit/Overdrive Protection
This system senses if there is a short circuit across the 350 output terminals and
disconnects the output to avoid amplifier dama e. It also senses if the 350 is
bein driven outside acceptable operational parameters. An example of this
would be drivin a 1Ω speaker at very hi h levels.
Note:
After the short circuit or overdrive sourc
e is removed, the 350 must be
turned off then back on to reset and resume operation.
hermal Protection
This system senses if the 350 is overheatin and disconnects the output until a
safe operatin temperature is reached, at which time the unit will autom
atically
resume normal operation.
Earthing
Perreaux en ineers pay particular attention to desi nin the product to ensure
maximum separation between internal si nal and power earths, only meetin at a
central starred point.
Earth
Isolation
Switch
The to
le switch on the rear of the 350 allows the internal circuitry to be
isolated from the mains earth, whilst still maintainin an earth connection to the
chassis. This ensures the potentially fatal practice of usin an AC cord-
set with
no earth connection, to alleviate system hum, is not required.
Highest
Quality PCBs
and
Components
Quality fibre lass PCBs, featurin heavy copper tracks and hi h-
rade
components, are used throu hout the 350. This provides added stability under
variable thermal or electric
al loads and assures maximum si nal inte rity,
separation and product life.
Bi-Wiring
Made Easy
Dual pairs of bindin posts per channel allow bi-
wirin of speakers to be
conducted easily.
Soft-Start
Circuitry
The 350 utilises soft-start circuitry to prot
ect the fuses and/or circuit breakers in
your home’s mains power supply. Without this circuit, the hu e inrush current
required to char e the 60,000µF of power supply smoothin capacitance can
blow the fuses or trip the circuit breakers.
Highly
Powered
Capable of continuously deliverin 350W
RMS
into 8Ω (600W
RMS
into 4Ω
), the
350 is hi hly powered. Utilisin ei ht hi h current Toshiba MOSFETs per
channel, the 350 handles even the most difficult loads with ease.

20
7
77
7 Maximising System Potential
Interconnects
and Speaker
Cables
An often-
i nored area in hi h fidelity systems is the cablin connectin the
various
components. Interconnect leads should be hi h quality cable with
substantial terminations. Gold plate is inherently resistant to corrosion, and an
excellent conductor. The presence of corrosion induces distortion and poor
conductivity will seriously interfere with sound quality. Terminations must plu
snu ly into sockets to maintain maximum conductivity and to avoid annoyin
earthin problems.
Spea
ker cablin is equally critical. Use only solidly constructed cable of hi h
purity copper or silver content. A ain, old plated terminations are
recommended, of the spade or banana plu type. Use cables of equal len th and
as short as possible to mainta
in uniform electrical resistance at the lowest
possible level. If your amplifier is closer to one of your speakers than the other,
avoid coilin the lon er lead as this can create inductance, with the potential of
reduced hi h frequency performance. Keep
all connections clean, firm and
ti ht. The traditional ada e that a chain is only as stron as its weakest link
most certainly applies to audio systems.
Bi-amping
Bi-
ampin uses two similarly powered amplifiers, with exactly the same input
sensitivity s
o that, when the same input si nal is provided to each of them, the
output level will be exactly the same. This can often be done with one power
amplifier connected to the tweeters and another to the woofers, as it spreads the
power requirement between the two amplifiers. Bi-
ampin can achieve reater
control, dynamics and resolution than if you try to run everythin from a sin le
stereo amplifier.
Balanced
Interconnects
The use of the balanced si nal inputs and outputs can have the effect of cleanin
up
hums, buzzes, radio frequency interference (RFI) and eneral extraneous
rubbish that can enter an audio system. A balanced si nal input system operates
on the principle of differential amplification. The positive and ne ative inputs
are contrasted a ain
st one another and the difference between them is amplified.
Noise enterin the system is imposed equally on the positive and ne ative
si nals and therefore will not be amplified, as no differential volta e exists.
The term used to describe the quality of
the effect is called Common M ode
Rejection Ratio (CM RR). CM RR is an equipment and system specification,
which describes how well unwanted common mode si nals are counteracted
when used in conjunction with balanced connections. CM RR action prevents
the e
ress and build up of extraneous hum; buzzes and RFI when analo ue
si nals are conveyed down cables and between equipment powered from
different locations and is widely used in professional audio applications.