How do you bridge an amp?

[Good4it]

Any why?

 

[Verdinut]

First, the amp as designed has to be bridgeable. Not all amps are.

If it is bridgeable, the manufacturer will indicate it in the published specs and explain how it's done in the owner's manual.

The purpose of bridging the two channels of a stereo amp is to obtain more power out in a single channel. Depending on the impedance of the speaker, some stereo amps will output up to 3 times or so the power of one channel when bridged.

 

[MR.MAGOO]

First, the amp as designed has to be bridgeable. Not all amps are.

If it is bridgeable, the manufacturer will indicate it in the published specs and explain how it's done in the owner's manual.

The purpose of bridging the two channels of a stereo amp is to obtain more power out of a single channel. Depending on the impedance of the speaker, some stereo amps will output up to 3 times or so the power of one channel when bridged.

So if you want more power and stereo you'd need 2 bridgeable stereo amps?

 

[ryanosaur]

yes, 2 bridged channels become one. it is important to remember that when doing this, the speaker impedance the amp sees is halved, so 8 ohms become 4... 4 ohms become 2...

 

[lovinthehd]

So if you want more power and stereo you'd need 2 bridgeable stereo amps?

Better yet just two sufficiently powerful amp channels (without bridging) in the first place...

 

[PENG]

Funny, the impedance being seen as halved thing could be misleading at times, but like the rms power thing, after being told so many times, it is probably considered as facts by most audiophiles. Actually the rms power thing is worst, I find it hard to accept because it is factually incorrect. The former is fine if stated the way Ryan did, could still be misleading to some, but not factually incorrect.

 

[ryanosaur]

Funny, the impedance being seen as halved thing could be misleading at times, but like the rms power thing, after being told so many times, it is probably considered as facts by most audiophiles. Actually the rms power thing is worst, I find it hard to accept because it is factually incorrect. The former is fine if stated the way Ryan did, could still be misleading to some, but not factually incorrect.

Not being the engineer, I took it mean something similar to the warning about speakers that dip low to 3.2 in lower frequencies and have bad phase angle...
But I’m still on the learning path here too.

 

[PENG]

Not being the engineer, I took it mean something similar to the warning about speakers that dip low to 3.2 in lower frequencies and have bad phase angle...
But I’m still on the learning path here too.

You said it the right way, it is something like this that is not just misleading, but just feel wrong:

"........it is worth noting that bridging cuts the resistance load or ohms in half; this can quickly cause your amplifier to overheat and shutdown. "

This is not too bad actually as it came from a pretty good and useful site, it gets worse if Google takes you to various forums. I understand people like to explain things in layman's term though but I think it isn't hard to understand a two channel amp can be bridged to produce double the voltage, and output more power, if designed for it.

 

[Good4it]

The purpose of bridging the two channels of a stereo amp is to obtain more power out of a single channel. Depending on the impedance of the speaker, some stereo amps will output up to 3 times or so the power of one channel when bridged.


How is it done?

 

[WaynePflughaupt]

Are you asking for a technical explanation, i.e. what goes on inside the amp when it is bridged? Or are you asking how the end user bridges an amp?

Regards,
Wayne A. Pflughaupt

 

[Good4it]

The end user.

 

[ryanosaur]

Crown xls series... see pg 7
https://3e7777c294b9bcaa5486-bc95634e606bab3d0a267a5a7901c44d.ssl.cf2.rackcdn.com/product_documents/documents/2555_1431029583/5055568_XLSDC2_MNL_PRINT_050615_original.pdf

 

[Good4it]

Crown xls series... see pg 7
https://3e7777c294b9bcaa5486-bc95634e606bab3d0a267a5a7901c44d.ssl.cf2.rackcdn.com/product_documents/documents/2555_1431029583/5055568_XLSDC2_MNL_PRINT_050615_original.pdf

Thank you

 

[lovinthehd]

Thank you

You have the Crown amp?

 

[Good4it]

Nope just curious. Didn’t know how it was done.

 

[lovinthehd]

Nope just curious. Didn’t know how it was done.

Just don't consider it a bluepeint for all amps. My take was it seemed a better idea until the more knowledgeable pointed out the foibles....

 

[markw]

With a NAD 214 one plugs the mono input into one channel (left, I think), connect the speaker to the two red terminals, and flip the "bridge" switch. That's it!

 

[highfigh]

Funny, the impedance being seen as halved thing could be misleading at times, but like the rms power thing, after being told so many times, it is probably considered as facts by most audiophiles. Actually the rms power thing is worst, I find it hard to accept because it is factually incorrect. The former is fine if stated the way Ryan did, could still be misleading to some, but not factually incorrect.

Care to elaborate WRT the impedance being effectively half of the normal load?

What is 'the RMS power thing'- you mean as a way to express output power?

 

[highfigh]

Nope just curious. Didn’t know how it was done.

That shows how it's done, but it doesn't explain what's happening- when bridging two channels into one, one input is inverted, so the signals will add together. The switch is for activating the circuit that does this (it could just be shutting off the input for the second channel) but it would be possible to accomplish the same by inverting the second channel before it goes to the amp's input jack in some amplifiers. Some older crossovers had a normal and inverted output, which is how they did it before the bridging switches were added to amplifiers. With amplifiers that use both + terminals, it's likely that one channel's signal is inverted internally.

NOTE- high powered car audio amplifiers ARE NOT considered 'common ground', which means the L and R speaker negative terminals are not at chassis ground potential and they're usually not common to both channels. This the reason the Left + and Right - terminals are used- the internal circuitry is different and using both + terminals won't work unless it's explicitly shown as the way to connect the load.

https://www.google.com/search?q=bridged+amplifier+waveform&tbm=isch&source=iu&ictx=1&fir=u8CzMCyar12KNM%3A%2C307Stsmt0yoWfM%2C_&vet=1&usg=AI4_-kRBxjInNJxDbyJZhwi62Ff56ON6zw&sa=X&ved=2ahUKEwj9n7r3v4_jAhVDGs0KHfOSCkcQ9QEwAnoECAEQCA#imgrc=u8CzMCyar12KNM:

 

[PENG]

Thank you

Be careful of one point, on page 7 it says:

"BRIDGE mode delivers the power of both amp channels into a single load of 4Ω or greater."

That's because the Crown audio XLS amps are rated 2 ohm minimum. Many power amps are not rated for such low impedance, so if your amp is rated 4 ohm minimum, then in bridge mode you should use to drive 8 ohm (or higher) speakers only.

Care to elaborate WRT the impedance being effectively half of the normal load?

What is 'the RMS power thing'- you mean as a way to express output power?

I did elaborate in post#8. No issue if words like your "effectively...", or Ryan's "the speaker impedance the amp sees is halved. Though it would be better if people just keep it simply by saying the amp's output voltage is doubled, for the same input signal, that would factual, impedance being halved is not factual, but again it is okay if "effectively, the amp sees... etc. are thrown in there.

The rms power thing is just another example of the power of the internet, that can turn something wrong to become acceptable. Someone as knowledgeable as you are surely know there is (or more like was now..) no such thing as rms watt or W rms like there are Vrms and Irms.