# Bridging 4-channel amp



## HiFiAudioGuy34 (Mar 30, 2011)

I have had a few people tell me that they bridge multi-channel amps as stereo and do it that way to get more rms wattage. Is that true? do you risk anything by using/wiring your amp/speakers this way? are amps made to? run a stereo signal bridged? do you sacrifice sq or anything along those lines?


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## HiFiAudioGuy34 (Mar 30, 2011)

really? no one has any input?


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## blazeplacid (May 19, 2008)

what amp? make/model?

yes you gain more wattage by bridging.

as far as sound quality, I haven't heard any difference in sound when I bridge the channels.

Most 4 channel amps are stable to 4ohms bridged


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## HiFiAudioGuy34 (Mar 30, 2011)

Fosgate Power t600-4. I'm planning on bridging all 4 channels (stereo) 300 RMS x 2 to a set of Hertz Hi energy HSK 163 3 way components (150w RMS each set L-R) in hopes to keep the amp cool and get high output along with good fidelity.


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## sqshoestring (Jun 19, 2007)

You actually get more distortion from the amp bridged, but its such a small amount it would rarely be noticeable in a car....while speakers have far more distortion. Also running the amp at lower ohm load would make it run hotter and be harder on the amp, though I would not worry about that amp long as it has cooling. If you take a typical 2/4 ohm amp and bridge two channels each channel 'sees' half the load; so 4 ohms bridged is 2 ohms to each of the two channels you have bridged....its the same as running it each channel at 2 ohms. On the other hand lots of people do what you are saying with no problems, in addition running mids and/or highs is not near as taxing on an amp as bass or powerful midbass so its not that hard on the amp anyway. It is easy enough to try it both ways when you hook it up if you want to test it bridged and non. It will get louder bridged, not much other difference. Most multi channel amps are made to run 2 or 4 ohms and double that when bridged, look up the manual to verify and if they say so its ok to do.


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## HiFiAudioGuy34 (Mar 30, 2011)

Yeah it does stereo bridged. 300x2 and its also stable down to 2 ohms bridged. im going to run it at 4 ohms bridged hoping to keep both gains a little more than half way so I'll get around 150x2 rms to each set.

the other option is to run it stereo unbridged which i'll get 100x2 rms 

going bridged and running the amp at half-gains compared to unbridged and running the gains at around 3/4's (or more) I always understood that if the gain was turned up higher and it pushed less power that would make amps run hotter and lead to distorition. therefore running front and rear channels bridged I could keep the gains at a lower setting and keep the amp cooler (also allowing more power to be produced). Does that make sense to you guys? or am i all sorts of wrong? lol


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## St. Dark (Mar 19, 2008)

The gain merely determines what level of input signal voltage gets the amp to produce it's rated power. So, while the gain pot has a physical midpoint to it's rotation, that isn't really halfway so to speak.
An amp will get hot based on what you are asking it to do on the output side. If it's doing X power at Y load, that's what it is doing. Where the gain knob is set will be determined by your source's output voltage and where you want it's volume knob to be to get you to that output. A radio with an "8v outputs" would have you setting your gain knob in a different physical position than a radio with "2v outputs" to get the amp to do a given output. The amp would generate the same heat in both cases

And yes, when you bridge you do increase the various distortions and lose some damping. On something like that Rockford it would be unlikely that it would have an appreciable affect on your overall sound, though.

As far as bridging it to the HSKs; sure. Go for it!
Or run them semi-active.


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## passtim (Sep 30, 2009)

You will actually get around 400wpc, make sure your components can handle the extra power. Actually the sound quality may increase do to the channel seperation increasing. It will also give you the ability to adjust your gains for each side. When i do this with my T400-4, I notice a vast improvement in sound quality.


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## HiFiAudioGuy34 (Mar 30, 2011)

thanks for the info guys! Can't wait will I get the whole setup in my car!


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## Huckleberry Sound (Jan 17, 2009)

? for someone...

I have the A400 from PPI Art Series. I am briding each side of the amp to get 200 x 2. Each side of the amp will be diving the Hybrid Audio L4. Here is my question. When bridging, do I need to still plug in the left and right input for each side. Or do I just put one input in rather it be left or right.

Thanks in advance!!!!


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## jockhater2 (May 9, 2011)

i bridged my stereo amp @ 4 ohms


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## supramkivtt2jz (Apr 12, 2011)

i bridged my current amp to run the sub until i receive my boston 5 channel. Theres supposed to be more distortion when bridged, but I havnt noticed anything in my current setup.


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## Commissionmip (Jan 27, 2011)

Please tell us how you made out with the hertz hsk 3 way bridged. Im currently in the process of doing this exact setup. Also, the 600-4 will be giving you somewhere around 300 rms to each crossover!!!!


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