Pro ceed AMP3 User manual

PRO C E E D
AMP 2 & AMP 3 Power Amplifiers

2
CAUTION
RISK OF ELECTRIC SHOCK
DO NOT OPEN
CAUTION: TO REDUCE THE RISK OF ELECTRICAL SHOCK, DO
NOT REMOVE COVER. NO USER-SERVICEABLE PARTS INSIDE.
REFER SERVICING TO QUALIFIED PERSONNEL.
WARNING: TOREDUCETHERISKOFFIREORELECTRICSHOCK,DO
NOT EXPOSE THIS APPLIANCE TO RAIN OR MOISTURE.
The lightning flash with arrowhead symbol, within an equilateral triangle, is intended to
alert the user to the presence of uninsulated “dangerous voltage” within the product’s en-
closure that may be of sufficient magnitude to constitute a risk of electric shock to per-
sons.
The exclamation point within an equilateral triangle is intended to alert the user to the
presence of important operating and maintenance (servicing) instructions in the literature
accompanying the appliance.
Marking by the “CE” symbol (shown left) indicates compliance of this device with the EMC
(Electromagnetic Compatibility) and LVD (Low Voltage Directive) standards of the
European Community.
The information contained in the manual is subject to change without notice. The most current version of this manual will
be posted on our web site at http://www.madrigal.com.

3
Important Safety Instructions
Please read all instructions and precautions carefully and completely before operating your Proceed power am-
plifier.
1. ALWAYS disconnect your entire system from the AC mains before connecting or disconnecting
any cables, or when cleaning any component.
2. This product is equipped with a three-conductor AC mains power cord which includes an
earth ground connection. To prevent shock hazard, all three connections must ALWAYS be
used. If your electrical outlets will not accept this type of plug, an adapter may be purchased.
If an adapter is necessary, be sure it is an approved type and is used properly, supplying an
earth ground. If you are not sure of the integrity of your home electrical system, contact a li-
censed electrician for assistance.
3. AC extension cords are not recommended for use with this product. If an extension cord must
be used, be sure it is an approved type and has sufficient current-carrying capacity to power
this product.
4. NEVER use flammable or combustible chemicals for cleaning audio components.
5. NEVER operate this product with any covers removed.
6. NEVER wet the inside of this product with any liquid.
7. NEVER pour or spill liquids directly onto this unit.
8. NEVER block air flow through ventilation slots or heatsinks.
9. NEVER bypass any fuse.
10. NEVER replace any fuse with a value or type other than those specified.
11. NEVER attempt to repair this product. If a problem occurs, contact your Proceed®retailer.
12. NEVER expose this product to extremely high or low temperatures.
13. NEVER operate this product in an explosive atmosphere.
14. ALWAYS keep electrical equipment out of the reach of children.
15. ALWAYS unplug sensitive electronic equipment during lightning storms.

4
From all of us at Madrigal Audio Laboratories, thank you for choosing the
Proceed power amplifier.
A great deal of effort went into the design and construction of this precision
device. Used properly, it will give you many years of enjoyment.

5
Table of Contents
Unpacking and Placement ........................................................................ 6
Unpacking .......................................................................................................... 6
Placement .......................................................................................................... 6
Ventilation ........................................................................................................... 6
Operating Voltage ...................................................................................... 7
AMP bottom-panel label............................................................................ 7
A Quick Start................................................................................................ 8
Special Design Features ............................................................................10
Multiple monaural design................................................................................ 10
Low impedance power supply ....................................................................... 10
Balanced inputs ............................................................................................... 10
Robust output stage......................................................................................... 10
Extensive protection ......................................................................................... 10
Home THX Audio System certification.............................................................. 11
Front Panel ..................................................................................................12
Rear Panel ..................................................................................................13
Remote turn-on tip polarity ...................................................................... 14
Bridged Operation .....................................................................................17
Bridging Explained ............................................................................................17
Balanced Bridging ............................................................................................17
Balanced Bridging Kit ................................................................................17
Balanced Bridged Input Connection ..................................................... 18
Single-Ended Bridging...................................................................................... 19
Single-Ended Bridging Kit ......................................................................... 20
Single-Ended Bridged Input Connection.................................................21
Biamplification .......................................................................................... 22
Balanced Y-adapter ................................................................................. 22
Biamping wiring diagram ......................................................................... 23
Care & Maintenance ................................................................................ 24
U.S. and Canadian Warranty .................................................................... 25
90-Day Limited Warranty.................................................................................. 25
Five Year Extended Warranty........................................................................... 25
Obtaining Service ..................................................................................... 26
Specifications ............................................................................................ 27
Dimensions: AMP 2 .................................................................................... 28
Dimensions: AMP 3 .................................................................................... 29

6
Unpacking and Placement
Unpacking Unpack your Proceed®AMP 2 or AMP 3 power amplifier and keep all packing
materials for future transport. Shipment of the amplifier without the original
packing material is not recommended. Locate and remove the heavy gauge AC
power cord, which is tucked into a cardboard slot within the box.
Placement Your Proceed AMP may be placed either near the preamplifier/control center or
near the loudspeakers. It may be placed on a shelf or in a cabinet where it is
convenient to operate.
Note that adequate clearance for the AC cord and connecting
cables must be left behind your AMP.We suggest leaving at least
three inches of free space behind your AMP to allow all cables
sufficient room to bend without crimping or undue strain.
Ventilation Be sure to allow 2 to 3 inches of clearance above your AMP to allow heat dissi-
pation through air circulation. The vents on both the bottom and the top of the
AMP must be kept free from any obstruction which would reduce the flow of air
through the unit. The best rule of thumb is this: if the top of your AMP is too
hot to touch when “idle,” it needs better ventilation. If so, consider drilling holes
in the supporting shelf under the AMP to promote flow-through ventilation, or
use fans to increase air circulation.
Open equipment racks are generally best for power amplifiers, as they allow
ample ventilation. If your amplifier must be located inside a cabinet which re-
stricts airflow, consider using some fans to increase ventilation.
Avoid placement on soft surfaces such as carpeting. If you prefer to have the AMP
on the floor near your loudspeakers, be sure to place it on a firm surface. (A
piece of tempered glass under the amplifier is aesthetically unobtrusive while
providing firm support and allowing the required ventilation.)
Mechanical drawings are included in this manual to facilitate special installations
and custom cabinet work (see “Dimensions” at the end of this manual).
PRECAUTION
For your protection, review “Important Safety Instructions”
before you install your AMP.

7
Operating Voltage
The Proceed AMP 2 and AMP 3 are factory-set for 100V, 120V, 220V, or 240V AC
mains operation at either 50 or 60Hz, according to the country for which the unit
was manufactured. (230V in European Union countries, in compliance with CE
regulations.) Make sure that the label on the bottom of the AMP indicates the
correct AC operating voltage for your location. The operating voltage cannot be
changed by the user, and any attempt to do so will void the warranty.
If the voltage indicated does not match the service in your area, see your Pro-
ceed dealer.
AMP bottom-panel label
WARNING: BEFORE ATTEMPTING TO OPERATE THIS DEVICE,
REFER TO OWNER’S MANUAL FOR PROPER OPERATING
INSTRUCTIONS AND SAFETY PRECAUTIONS.HAZARDOUS
VOLTAGE AVAILABLE INSIDE; DISCONNECT AC – MAINS
CABLE BEFORE OPENING UNIT.
designed and manufactured in USA
MADRIGAL AUDIO LABORATORIES, INC.
No User Serviceable Components Inside.
For service,contact Madrigal Audio Laboratories or an Authorized
Dealer.Any modification to this equipment will void all warranties.
Manufactured under license from Lucasfilm Ltd. Additionally licensed under the following patents:
U.S. number 5,043,970; 5,189,703; and 5,222,059. Foreign patents pending. Lucasfilm THX Audio,
Lucasfilm, and Home THX Cinema are registered trademarks of Lucasfilm Ltd.
amp S/N
PRO C E E D
R

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A Quick Start
We recognize that many people are understandably eager to begin listening to
their new components, and that reading the manual is often done (if at all) at a
later time—perhaps while listening to music through the new product itself. We
strongly recommend that you read this manual thoroughly.
Fortunately, we can help you get some music up and running on your system
quickly, so that you may begin enjoying your new amplifier while reading more
about it. The goal here is simply to make some music as quickly as possible.
The following procedure assumes that the rest of your system is already con-
nected (e.g., source components to preamplifier).
1 TURN DOWN THE VOLUME ON YOUR PREAMPLIFIER
Turning the volume on the preamp all the way down minimizes the oppor-
tunity for unpleasant surprises when first powering up your new amplifier.
It does not need to be turned off—merely turned down.
2 SELECT “XLR” OR “RCA” WITH THE “INPUT SELECT” SWITCHES
Each channel of the Proceed AMP 2 and AMP 3 has both balanced (XLR)
and single-ended (RCA) inputs, with a small switch between the two con-
nectors to select between them. Using these switches, select the appropriate
input for each channel, given your interconnecting cables and preamplifier’s
capabilities.
3 CONNECT YOUR PREAMP TO THE AMP
Having selected the appropriate inputs in Step 2, now connect the outputs
of your preamplifier to the corresponding inputs on the power amplifier.
4 CONNECT YOUR SPEAKERS TO THE AMP
Each channel of the Proceed AMP 2 and AMP 3 is supplied with two sets
of binding posts to facilitate bi-wiring. Using either the top or the bottom
set of red and black binding posts, connect speaker wire from the AMP to
your loudspeakers. Be sure to maintain consistency in polarity, e.g., the red
post on the amplifier to the red connector on the speaker, and likewise
black to black. (Getting the wires mixed up won’t damage anything, but the
sound will be lacking in bass and the imaging will be quite poor and un-
stable.)
5 CONNECT THE AC CORD TO THE AMP AND TO YOUR AC OUTLET
The AC receptacle for the power cord is located on the right side of the
rear panel, as seen from the front. The AMP will initially power up in
standby mode.

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6 TURN ON THE AMP BY PRESSING THE POWER BUTTON
Pressing the latching power button on the front panel of the AMP 2 and
AMP 3 will connect the amplifier to the AC mains. If the indicator light
does not light, the amplifier is either not receiving AC power or its pro-
tection circuitry has been engaged.
7 SLOWLY RAISE THE VOLUME ON YOUR PREAMPLIFIER
Congratulations! You should now be able to enjoy your favorite music while
reading the rest of this manual. (Please, do read the rest of this manual. It
contains much valuable information about your new amplifier which we
could not possibly fit onto these two pages.)

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Special Design Features
Congratulations on your purchase of a Proceed AMP! While your new amplifier is
straightforward in its use, it includes several design features which are responsible
for its outstanding performance. A few of these are given below.
Multiple monaural design Consistent with the finest amplifiers, your Proceed AMP is a true “multiple mon-
aural” design. Each audio channel has its own, dedicated power supply—includ-
ing a separate 300VA toroidal transformer for each channel. This approach re-
duces crosstalk between audio channels for superior imaging and reproduction
of acoustic space. The demands placed on one channel have virtually no effect
on the performance of the other channel(s).
Low impedance power supply A critical factor in the ultimate performance of an amplifier is its “power supply
impedance,” which can be loosely thought of as the freedom with which the au-
dio circuitry has access to the power it needs, when it needs it. The design of
your Proceed AMP has addressed this important characteristic in a comprehen-
sive fashion. For example, the power supply capacitors (which act as “reservoirs”
of power for the amplifier circuitry) are mounted directly to the printed circuit
board, immediately adjacent to the output transistors (which require the greatest
amount of current). The layout of the circuitry uses short, thick traces for high
current paths. Internal current capability is further enhanced with high purity
copper buss bars. This attention to detail yields an optimal environment in which
the amplifier may operate to its maximum potential.
Balanced inputs Each channel of your AMP is individually configurable to receive either balanced
or single-ended inputs. This approach allows you to take full advantage of the
greater immunity from noise, RFI, and EMI which balanced transmission of audio
signals offers on any preamp-to-amplifier connection where it is supported. At
the same time, any or all channels of the amplifier may be configured for single-
ended inputs to maintain compatibility with the majority of preamplifiers avail-
able today. The gain structure of the AMP adjusts automatically when you select
different inputs to facilitate this “mix and match” approach.
Robust output stage Each channel of your Proceed AMP uses eight 150 watt power transistors. These
transistors are all individually tested and sorted, and are used in matched sets to
ensure that no one transistor bears a disproportionate part of the overall load.
The combination of an “overbuilt” design specification and extraordinary attention
to detail in manufacturing improves performance, reliability, and longevity.
Extensive protection Your Proceed amplifier will shut itself down if it senses either the presence of
DC (direct current) at the output or an unsafe operating temperature. In either
case, a power relay will cause the amplifier to be disconnected from the AC
mains. In addition, the AC input to each transformer is fused to protect against
excessive current conditions such as driving shorted outputs. Finally, inrush limit-
ing prevents premature aging of power supply components during power-up, and
switches off-line once the power supply has been charged.

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Home THX Audio
System certification Lucasfilm, Ltd.®has established minimum standards for the performance of vari-
ous components which may be used in their Home THX®Audio System. With
respect to power amplifiers, the standards address such things as:
• a low electrical noise floor to allow low-level information to be
fully appreciated;
• the absence of any mechanical noise (fans noise, transformer wind-
ing buzzes), for the same reason;
• adequate power to meet the demands of modern films (which can
be quite dynamic);
• flat frequency response for accurate reproduction of timbre;
• stability into relatively extreme loudspeaker loads, to ensure that
the amplifier will perform well with a wide range of loudspeakers.
As you can see from this list, there is nothing about the Home THX amplifier
specification that is particularly radical. It simply ensures a certain minimum
standard of performance. In particular, there is nothing in the nature of the
amplifier specification which prevents anyone from going above and beyond
the minimum performance levels required by THX certification.
Both the Proceed AMP 2 and AMP 3 are certified for use in Home THX audio
systems. In these products, Madrigal engineers have created powerful, versatile
and extraordinarily musical power amplifiers, using the technology and design
methodology for which they have become so well known. Equally suited to the
rigors of film soundtracks and the finesse of high end music reproduction, the
Proceed amplifier serves both needs quite well. In today’s growing market for
multi-purpose systems, they represent an extraordinary value.

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3
a m p channel power amplifier
power
PRO C E E D
2
amp channel power amplifier
power
PRO C E E D
21
Front Panel
1POWERBUTTON
Pressing the latching power button connects the amplifier to the AC
mains, turning it on. Power consumption when fully on and at idle is ap-
proximately 140 watts for the AMP 2 and 210 watts for the AMP 3.
At your option, you may also toggle the AMP between a standby mode
and fully on by connecting its remote turn on jack to the corresponding
remote turn on output on a Proceed control unit such as the PAV, PRE, or
even the CDP. Power consumption in standby mode is extremely small—
just a few watts for the circuitry which controls the turn-on procedure.
Note that if the amplifier has been disconnected from the AC mains
power by depressing the front panel power button, it cannot respond to
a remote turn-on command from a control unit.
2 INDICATOR LIGHT
The indicator light glows either amber or red, depending on the opera-
tional status of your AMP. Amber indicates that the AMP is on and ready
to be used. When the indicator light is glowing red, the unit is in
standby (see 1 above). If the indicator light is completely off, the ampli-
fier is not receiving power. Check your AC connections and the rear-
panel AC fuse.

13
PUSH
21
3
PUSH
21
3
PUSH
21
3
PUSH
21
3
PUSH
21
3
mains fuse
100-120VAC:
8A 3AG fast acting
200-240VAC:
4A 3AG fast acting
remote
turn-on
~ ac
mains
+ outputs –
input select
channel 1 (right) when viewed from the front
+ outputs –
input select
channel 2 (left) when viewed from the front
mains fuse
100-120VAC:
12A 3AB fast acting
200-240VAC:
6A 3AG fast acting
remote
turn-on
~ ac
mains
+ outputs –
input select
channel 1 (right) when viewed from the front
+ outputs –
input select
channel 3 (left) when viewed from the front
+ outputs –
input select
channel 2 (center) when viewed from the front
1 2 3 4 5 6 7
Rear Panel
Caution! Turn the volume on your preamplifier all the way down
before attempting to connect anything to your Proceed
AMP 2 or AMP 3.
1 AC MAINS RECEPTACLE
Connect the AC power cord (included in the accessory pack) to the I.E.C.-
standard AC receptacle on the rear panel of the AMP, then to the AC mains
outlet.
Warning! The Proceed AMP has been safety-tested and is designed
for operation with a three-conductor power cord. Do not
defeat the “third pin” or earth ground of the AC power cord.

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2 REMOTE TURN-ON JACK
A 1⁄8" “mini” jack above the AC mains receptacle on the rear panel allows
remote-controlled turn-on (that is, toggling between operate and
standby) of the Proceed AMP. This remote “trigger” will be operated by a
3–12 volts DC positive-polarity pulse, of at least 100 milliseconds dura-
tion, with tip polarity as shown below:
Remote turn-on
tip polarity
+– 3-12 volts for at
least 100 mS
Your Proceed dealer can help you take advantage of these design features
to maximize your system’s versatility.
3 AC MAINS FUSE
One fast-blow fuse is located on the rear panel of the AMP. If it should be-
come necessary, replace the fuse with the same type only. Refer to the fol-
lowing table for replacement values.
AMP 2 AMP 3
100V to 120VAC 8 amp 12 amp
200V to 240VAC 4 amp 6 amp
Caution! ALWAYS remove the AC cord before removing the fuse!
4 SPEAKER BINDING POSTS
The Proceed AMP is equipped with gold-plated, high-current binding
posts for output termination to a loudspeaker system. To take full advantage
of the AMP’s sonic quality, we recommend using high-quality speaker cable;
see your Proceed dealer.
Caution! NEVER connect the Proceed AMP output terminals to any
device other than a loudspeaker.
NEVER short-circuit the amplifier's output terminals.
NEVER connect the left-channel output terminals to the right-
channel output terminals.
There are two recommended methods for connecting speaker cables to the
Proceed AMP. A high-quality spade lug or hook lug, soldered to the cable
(or crimped with extremely high pressure), is best.

15
Spade lug Hook lug
Connect the left-channel +(positive or red) output post of the Proceed
AMP to the +(positive or red) input terminal of the appropriate loud-
speaker.
Connect the left-channel –(negative or black) output post of the AMP to
the –(negative or black) input terminal of the appropriate loudspeaker.
Repeat this procedure for the remaining channel(s).
5 BALANCED AUDIO INPUTS
Accepts right-channel and left-channel signals from preamplifiers with bal-
anced outputs via high quality XLR connectors.
The pin assignments of these XLR-type female input connectors are:
PUSH
21
3
Pin 1: Signal ground
Pin 2: Signal + (non-inverting)
Pin 3: Signal – (inverting)
Connector ground lug: chassis ground
These pin assignments are consistent with the standards adopted by the
Audio Engineering Society. Refer to the operating manual of your balanced-
output preamplifier to verify that the pin assignments of its output connec-
tors correspond to your Proceed AMP. If not, wire the cables so that the ap-
propriate output pin connects to the equivalent input pin.
If you are planning to use balanced connections between your preamplifier
and any particular channel of the AMP, select the balanced input by sliding
the input select switch (see Item 6, below) toward the XLR input. Then
connect the balanced outputs of your preamplifier to the corresponding
balanced inputs on the AMP.
6 INPUT SELECT SWITCH
This small switch is found between the balanced XLR input and the single-
ended RCA input on each channel of the AMP. Use it to select which of the
two inputs you plan to use.
The input select switch disables the unselected input in order to avoid any
pickup of stray noise from an open input. It also causes the effective
gain of that channel to be adjusted (either 23 dB balanced or 29 dB
single-ended, to compensate for the 6 dB difference in signal level in
these two connection standards). Should you use your AMP in a home
theater system, this adjustment allows you to use any combination of
balanced and single-ended connections without having to worry about
going outside the adjustment range of your Dolby™ Pro Logic™
decoder’s output calibration circuitry.

16
7 SINGLE-ENDED INPUTS
These RCA connectors accept single-ended inputs from preamplifiers with
single-ended (RCA) outputs.
Connect the left-channel single-ended outputs of your preamplifier to the
left-channel single-ended input on the AMP. Repeat for the remaining
channel(s).

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Bridged Operation
Your Proceed amplifier has been designed to be extremely versatile. Should
your needs change or grow over time, you may wish to add additional power
by one of two means: Bridging, or Biamping. We will discuss bridged opera-
tion first.
Bridging Explained Bridging refers to the act of reconfiguring the circuitry in both the left and
right channels of your amplifier to act as though it were a single, much larger
amplifier. (Of course, you will need a second bridged amplifier for stereo;
more for multichannel sound, as in home theater applications.)
Bridging is accomplished by sending a normal signal to one channel and an
inverted signal to the other. In this configuration, one channel will always be
“pushing” when the other is “pulling.” By connecting the loudspeaker leads
across the left and right red output terminals, the amplifier can now deliver
twice the normal voltage to the loudspeaker. Working together this way, the
two amplifier channels can deliver almost four times the power to a speaker
that a single channel could deliver on its own.
Bridged operation is particularly beneficial with low sensitivity, high-imped-
ance loudspeakers (8Ωor higher) that have a greater need for voltage than for
current. It is not recommended for low-impedance loudspeakers, as the
speaker’s impedance is “split” by the two halves of the amplifier. Thus the
bridged amplifier “sees” a 2Ωload when connected to a 4Ωloudspeaker. De-
livery of high power into such a low impedance creates a great deal of heat
that needs to be dissipated. (Of course, your amplifier is protected against
overheating, but having an amplifier shut itself down even temporarily can put
a damper on the evening’s entertainment.)
Balanced Bridging If your preamplifier has balanced outputs, you should use them. For this dis-
cussion, we will assume that you are using a Madrigal Balanced Bridging Kit
for each channel to be bridged. (Alternatively, you may have custom cables
built using your preferred wire and connectors, being careful to follow the
wiring diagram below.)
Balanced Bridging Kit
21
3
12
3
12
3
Female XLR Input
Pin 1: signal ground
Pin 2: signal + (non-inverting)
Pin 3: signal – (inverting)
Male XLR Output (normal)
Pin 1: signal ground
Pin 2: signal + (non-inverting)
Pin 3: signal – (inverting)
Male XLR Output (inverted)
Pin 1: not used (floated)
Pin 2: signal – (inverting)
Pin 3: signal + (non-inverting)
Balanced Bridging
Input Adapter
(pin configuration)
Bridging Output Adapter
(not drawn to scale)
(shield not connected)

18
The “normal” leg of the Madrigal Balanced Bridging Input Adapter will be
marked with a red stripe to indicate positive polarity, and the inverted leg will
be marked with a black stripe to indicate inverted polarity (corresponding to
the red and black terminals of your loudspeaker).
The Balanced Bridging Output Adapter is simply a heavy-gauge copper bar
(silver- and gold-plated) used to strap two of the output ground terminals to-
gether. This establishs a common reference for the amplifier and completes
the circuit that includes the loudspeakers.
Important! Do not attempt to operate your amplifier in a bridged mode
without first strapping the black output terminals together.
Failure to establish a common ground reference between
the two channels can damage your amplifier by forcing
significant currents to flow where they do not belong!
To bridge your Proceed amplifier using a balanced input signal, follow these
steps:
1 DISCONNECT YOUR AMPLIFIER FROM EVERYTHING
Start with your amplifier totally disconnected from inputs, outputs, and AC
power. It is always best to power down an amplifier before changing con-
nections; here you are also changing its basic configuration, making it
essential.
2 CONNECT THE BALANCED BRIDGING INPUT ADAPTER TO THE AMP’S
INPUTS
Connect the two male XLRs to the inputs of your amplifier, noting which
XLR is marked red and which is black. The channel with the red, normal
input will later be connected to the red, positive terminal of your loud-
speaker. Don’t forget to choose the balanced input on each channel using
the switch located between the XLR and the RCA connectors.
Balanced Bridged
Input Connection
mains fuse
100-120VAC:
8A 3AG fast acting
200-240VAC:
4A 3AG fast acting
PUSH
channel 1 (right) when viewed from the front
PUSH
channel 2 (left) when viewed from the front
Madrigal Balanced Bridging Input Adapter
from preamplifier
loudspeaker terminals
Madrigal Bridging Output Adapter
inverting non-inverting

19
3 CONNECT THE BALANCED BRIDGING OUTPUT ADAPTER TO TWO
BLACK OUTPUT TERMINALS
All Proceed amplifiers have two sets of output terminals per channel, wired
in parallel (for convenience when biwiring). You may use either of the
black output terminals. Connect one end of the Balanced Bridging Output
Adapter to a black output terminal on one of the two channels to be
bridged together, and then connect the other end of the Output Adapter to
a black output terminal on the other channel. Make sure these connections
are snug and secure.
4 CONNECT YOUR LOUDSPEAKER WIRE ACROSS TWO RED OUTPUT
TERMINALS, ONE TO EACH OF THE TWO CHANNELS BEING BRIDGED
Connect the positive/+/red binding post of your loudspeaker to the red
output terminal associated with the red (normal) side of the Input Adapter.
Connect the negative/–/black binding post of your loudspeaker to the red
output terminal on the other side of the amplifier, the one associated with
the black (inverted) side of the Input Adapter.
Following this connection convention preserves the polarity of the signal
sent to the loudspeaker. In practice, the most important thing is to be con-
sistent throughout the system, as inconsistency will result in out-of-phase
loudspeakers. In turn, this results in unstable imaging and poor bass repro-
duction. (The effect is not dangerous, but neither is it desirable.)
5 CONNECT ONE OUTPUT CHANNEL OF YOUR PREAMPLIFIER TO THE
INPUT OF YOUR BRIDGED AMPLIFIER
The female XLR at the junction of the Balanced Bridging Input Adapter is
now the single input to this bridged pair of amplifier channels.
6 POWER UP YOUR AMPLIFIER
Plug the amplifier back into the AC mains; press the power button to
turn on the amplifier.
7 REPEAT THIS PROCESS WITH YOUR OTHER AMPLIFIER(S)
Single-Ended Bridging If your preamplifier has only single-ended (RCA) outputs, a few details of
bridged operation will differ from the discussion above, all pertaining to the con-
nection of the preamp to the bridged amplifiers. For this discussion, we will as-
sume that you are using a Madrigal Single-Ended Bridging Kit for each chan-
nel to be bridged. (Alternatively, you may have custom cables built using your
preferred wire and connectors, being careful to follow the wiring diagram be-
low.)

20
Single-Ended Bridging Kit
12
3
12
3
Female RCA Input
Skirt: signal ground
Center: signal + (non-inverting)
Male XLR Output (normal)
Pin 1: signal ground
Pin 2: signal + (non-inverting)
Pin 3: signal ground
Male XLR Output (inverted)
Pin 1: signal ground
Pin 2: signal ground
Pin 3: signal + (non-inverting)
Single-Ended Bridging
Input Adapter
(pin configuration)
Bridging Output Adapter
(not drawn to scale)
The “normal” leg of the Madrigal Single-Ended Bridging Input Adapter will be
marked with a red stripe to indicate positive polarity, and the inverted leg will be
marked with a black stripe to indicate inverted polarity (corresponding to the
red and black terminals of your loudspeaker).
The Balanced Bridging Output Adapter is simply a heavy-gauge copper bar
(silver- and gold-plated) used to strap two of the output ground terminals to-
gether. This establishs a common reference for the amplifier and completes
the circuit that includes the loudspeakers.
Important! Do not attempt to operate your amplifier in a bridged mode
without first strapping the black output terminals together.
Failure to establish a common ground reference between
the two channels can damage your amplifier by forcing
significant currents to flow where they do not belong!
To bridge your Proceed amplifier using a single-ended (RCA) input signal, fol-
low these steps:
1 DISCONNECT YOUR AMPLIFIER FROM EVERYTHING
Start with your amplifier totally disconnected from inputs, outputs, and AC
power. It is always best to power down an amplifier before changing con-
nections; here you are changing its basic configuration, making it essential.
2 CONNECT THE SINGLE-ENDED BRIDGING INPUT ADAPTER TO THE
AMP’S INPUTS
Connect the two male XLRs to the inputs of your amplifier, noting which
XLR is marked red and which is black. You may want to standardize on
“Red is Right” to avoid confusion, although it makes no difference to the
amplifier. The channel with the red, normal input will later be connected to
the red, positive terminal of your loudspeaker.