Help out a noob


the noob
Unregistered guest
can someone explain what bridging an amp means!?

Bronze Member
Username: Jlprix91

West, Michigan Usa

Post Number: 34
Registered: Oct-04
When you have a 2-channel amp you can bridge the channels get more power to your subs,
when you bridge a 2-channel it is like using a mono amp w/o the benefits from a mono amp

Silver Member
Username: Jmloughrey

Farmington, CT

Post Number: 720
Registered: Jul-04
bridging an amp takes 2 channels and connects them together more or less, say your amp does puts out 400 watts RMS @ 2 ohms into 2 channels, if you bride that amp you're probably gonna get something like 800watts rms x 1 @ 4ohms...its like a way or linking the channels for more power...when bridging 95% of 2channel amps are only bridgable to 4 ohms. Oh the amp it will tell you which of the pos. and neg terminals to use...

Gold Member
Username: Glasswolf

NorthWest, Michigan USA

Post Number: 7139
Registered: Dec-03
What is "Bridging"?

Bridging an amplifier refers to configuring a two channel (stereo) amplifier to drive a single load with more power than the sum of the two original channels combined. For an example, a 100 watt per channel at 4 ohms amp may put out 400 watts(one channel at 4 ohms) after bridging.

There are important things to know about running an amplifier in the bridged mode:
An amplifier running in bridged mode has one output channel to which a load (speaker) can be connected. It is no longer a two channel (stereo) amp as far as input signals and loads are concerned.
If the amp you want to run in bridged mode does not have built in facilities for doing so, you should not attempt to use it in this manner (unless you are thoroughly sure of what you are doing).
If you run bridged amplifiers, you must pay close attention to speaker phasing (see next item). Otherwise, you may have "hollow" or "weak" sound.
You must pay close attention to speaker wiring. The manufacturer will state which terminal is really the "positive" connection when bridged.
The speaker output signals of a bridged amplifier are floating; such connections must never be connected to any grounded device (such as an external accessory power meter, for example). If you do make such an illegal connection, one amplifier channel is basically short circuited (worst case result is a blown amplifier!).
Amplifiers running in bridged mode are generally limited to speakers with impedance ratings of no less than 4 ohms (in other words don't use a 2 ohm speaker load unless the manufacturer specifically allows it).

Bridged amplifiers work basically as follows:
A single input signal is applied to the amplifier. Internal to the amp, the input signal is split into two signals. One is identical to the original, and the second is also identical except it is inverted (sometimes called phase-flipped). The original signal is sent to one channel of the amp, and the inverted signal is applied to the second channel. Amplification of these two signals occurs just like for any other signal. The output results in two channels which are identical except one channel is the inverse of the other. The speaker is connected between the two amplifier speaker output terminals. In other words, one channel "pulls" one way while the second channel "pulls" in the opposite direction. This allows considerably more power to be delivered to a single load.

If we had our perfect amplifier, upon bridging it we would have a single channel amplifier with exactly four times as much power as any one channel of the amplifier in "normal" stereo mode, assuming a 4 ohm speaker load. This is because the effective output voltage available to drive the speaker has doubled as a result of bridging. A doubling of voltage on a given load results in a fourfold increase of power delivered to that load. If we used a 4 ohm load on the perfect bridged amplifier, the output power would be a very substantial eight times the normal stereo single channel 4 ohm output! These numbers should give some clues as to why real world amplifiers cannot meet such expectations. Once again, we are back to limitations of the power supply. In reality, most amplifiers in bridged mode will put out about 3 times the power as any one channel of the amp in normal stereo mode. The fourfold increase cannot be achieved because the power supply is unable to provide the current required for such performance. With 2 ohm loads, the situation is compounded. The amount of current required to drive a 2 ohm load when in bridged mode will tax the amplifier's power supply to its absolute limits. Not to mention, the output stage may not be able to safely handle the extra heat that will be dissipated.
Bottom line: stay away from 2 ohm loads if you are running an amplifier in bridged mode!

for shizzle
Unregistered guest
"Bottom line: stay away from 2 ohm loads if you are running an amplifier in bridged mode!"

Does this mean not do it even if the amp says it's ok???
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