Operating Manual
Balanced Bridging Kit
Single-Ended Bridging Kit
Balanced Y-Adapter
Single-Ended Y-Adapter
Madrigal Audio Laboratories, Inc.
Bridged Operation ....................................... |
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Bridging Explained ........................................ |
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Balanced Bridging ........................................ |
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Balanced Bridging Kit ................................... |
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Balanced Bridged Input Connection ........ |
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Single-Ended Bridging .................................. |
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Single-Ended Bridging Kit ............................. |
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Single-Ended Bridged Input Connection ... |
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Biamplification ............................................. |
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Biamplification Explained ............................ |
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Balanced Y-adapter ..................................... |
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Passive “vertical” biamping diagram ......... |
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U.S. and Canadian Warranty ....................... |
9 |
Obtaining Service ...................................... |
10 |
Bridging Explained
Balanced Bridging
Balanced Bridging Kit
Bridged Operation
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-imped- ance 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.)
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:
Balanced Bridging Input Adapter
(pin configuration)
2 1
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)
1 2
3
(shield not connected)
1 2
3
Male XLR Output (inverted)
Pin 1: not used (floated) Pin 2: signal – (inverting)
Pin 3: signal + (non-inverting)
Bridging Output Adapter
(not drawn to scale)
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.
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Important!
Balanced Bridged
Input Connection
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 included 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.)
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:
1DISCONNECT 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.
2CONNECT 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 Balanced Bridging Input Adapter |
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non inverting |
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DU L MONAUR L POWER AMP I I R Nº 3 3 |
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loudspeaker terminals |
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Madrigal Bridging Output Adapter |
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3CONNECT 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.)
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4CONNECT 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 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 consistent throughout the system, as inconsistency will result in out-of- phase loudspeakers. In turn, this results in unstable imaging and poor bass reproduction. (The effect is not dangerous, but neither is it subtle.)
5CONNECT 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.
6POWER 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.
7REPEAT 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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