Mark Levinson Bridge-Kit Owners Manual
Operating Manual
Balanced Bridging Kit
Single-Ended Bridging Kit
Balanced Y -Adapter
Single-Ended Y -Adapter
Madrigal Audio Laboratories, Inc.
Bridged Operation ....................................... 2
Bridging Explained ........................................ 2
Balanced Bridging........................................ 2
Balanced Bridging Kit...................................2
Balanced Bridged Input Connection ........ 3
Single-Ended Bridging .................................. 4
Single-Ended Bridging Kit ............................. 5
Single-Ended Bridged Input Connection... 6
Biamplification ............................................. 7
Biamplification Explained ............................ 7
Balanced Y -adapter.....................................7
Passive “vertical” biamping diagram ......... 8
U.S. and Canadian Warranty....................... 9
Obtaining Service ...................................... 10
Bridged Operation
Bridging Explained Bridging refers to the act of reconfiguring the circuitry in both the left and
right channels of an 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-impedance loudspeakers (8Ω or higher) that have a greater need for voltage than for
current. It is not recommended for loudspeakers that have an impedance significantly below 4Ω, as the speaker’s impedance is “split” by the two halves of
the amplifier. Thus the bridged amplifier “sees” a 2Ω load when connected to
a 4Ω loudspeaker. Prolonged delivery of high power levels into such a low
impedance creates a great deal of heat that needs to be dissipated. (Of course,
Madrigal amplifiers are 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, use a Madrigal Balanced Bridging
Kit for each channel to be bridged. This kit is comprised of two pieces: and
input cable that splits the incoming signal (inverting one side only), and a
ground bus bar that ties the output ground terminals together and allows
ground currents to flow through an extremely low impedance.
These cables are wired internally as indicated below:
Male XLR Output (normal)
Balanced Bridging Kit
Balanced Bridging
Input Adapter
(pin configuration)
21
3
Female XLR Input
Pin 1: signal ground
Pin 2: signal + (non-inverting)
Pin 3: signal – (inverting)
Bridging Output Adapter
(not drawn to scale)
Pin 1: signal ground
Pin 2: signal + (non-inverting)
Pin 3: signal – (inverting)
12
3
(shield not connected)
12
3
Male XLR Output (inverted)
Pin 1: not used (floated)
Pin 2: signal – (inverting)
Pin 3: signal + (non-inverting)
The “normal” leg of the Madrigal Balanced Bridging Kit will be marked with a
red stripe on the XLR to indicate positive polarity, while the XLR on the inverted leg will be solid black to indicate inverted polarity.
2
The Bridging Output Adapter is simply a bus bar of solid copper (with gold
over silver plating) used to strap two of the output ground terminals together.
This establishes a common ground reference for the amplifier and completes
the circuit that includes the loudspeakers. (There are two such bus bars in-
cluded in each kit: one appropriate for Mark Levinson 300-series amplifiers,
and one appropriate for Proceed amplifiers. Use whichever is appropriate, or
heavy guage speaker wire if for some reason the bus bars cannot be used.)
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 Madrigal 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
connections; here you are also changing its basic configuration.
Balanced Bridged
Input Connection
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. 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.
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Madrigal Bridging Output Adapter
Madrigal Balanced Bridging Input Adapter
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loudspeaker terminals
3 CONNECT ONE END OF THE BALANCED BRIDGING OUTPUT
ADAPTER TO TWO SIDE-BY-SIDE BLACK OUTPUT TERMINALS
Connect one end of the Balanced Bridging Output Adapter to an upper
black output terminal on one side of the amplifier, and then connect the
other end to a black output terminal on the other side of the amplifier.
(The two connections should be side-by-side rather than one above the
other.) Make sure these connection are snug and secure. (The upper
black connectors are used on Mark Levinson 300-series amplifiers since
strapping the lower black terminals would inhibit access to the communication ports and AC cord. Electrically, it would make no difference.)
3
4 CONNECT YOUR LOUDSPEAKER WIRE ACROSS TWO SIDE-BY-SIDE,
RED OUTPUT TERMINALS
In this case, you may use either the upper or the lower red output terminals. Connect the positive/+/red binding post of your loudspeaker to the
red output terminal associated with the red (normal) side of the In-
put 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
consistent throughout the system, as inconsistency will result in out-ofphase loudspeakers. In turn, this results in unstable imaging and poor
bass reproduction. (The effect is not dangerous, but neither is it subtle.)
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 amplifier.
6 POWER UP YOUR AMPLIFIER
Remember that a Mark Levinson power amplifier incorporates inrush
protection circuitry that allows its power supply to charge up gently, enhancing its longevity. Plug the amplifier back into the AC mains; press
the standby button once to bring the amp from off to standby; wait at
least ten seconds; and press the standby button again to bring it from
standby to operate.
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
connection of the preamp to the bridged amplifiers—resulting in your use of a
Madrigal Single-Ended Bridging Kit for each channel to be bridged.
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