Help! Power amp impedance question

[redbeard1206]

I'm in the market for a power amp but fairly new to how they work. Here's the gist:
I need a power amp that I'll be running into a cab rated at 4 ohms. I'll be running the power amp at bridged-mono. Does this mean that I need to run the amp at 8 ohms bridged? I've read a few pages on it, and my understanding is that the current and voltage double in bridged mode. So I could run one channel of the power amp (in stereo) at 4 ohms into my 4 ohm cab, but to bridge I need to run the power amp at 8 ohms bridged into my 4 ohm cab. Is this correct? Would running 4 ohms bridged mean I need to run a 2 ohm cab? Appreciate any help, I'm new to this.

 

[Bass_Pounder]

Your cabs impedance will remain the same. If it is 4 ohms, it will always be 4 ohms.

What you need is a power amp than can run safely at 2 ohms per channel (in stereo or dual mono mode), so that when bridged the amp will be able to handle a 4 ohm load.

 

[redbeard1206]

So for example, in the link below:
http://www.sweetwater.com/store/det...D=-1&zmam=89202644&zmas=1&zmac=1&zmap=IPR1600

The specs show that in bridged mode, the amp runs 1000W @ 2ohms.
I could run it bridged into a 4 ohm cab?

 

[redbeard1206]

Except that Peavey can run 800W per channel at 2 ohms, bridged that should be 1600W. How could I bridge that to a 4 ohm cab?

 

[billfitzmaurice]

How could I bridge that to a 4 ohm cab?

You plug it in. But you won't get 1600w into 4 ohms. It's only rated for 1,000w into 2 ohms. Into 4 ohms you may get 700w.

I've read a few pages on it, and my understanding is that the current and voltage double in bridged mode

They do not. You can double the voltage with series bridging, or you can double the current with parallel bridging. But you can't do both.

 

[redbeard1206]

Got it. Thanks, I appreciate the info guys. One of the reasons TB is the best forum around.