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Noob Bridge Question

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mitchiemasha View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote mitchiemasha Quote  Post ReplyReply Direct Link To This Post Topic: Noob Bridge Question
    Posted: 23 December 2017 at 5:09pm
I'm far from a noob but I've totally confused myself.

i, When putting 2 8 ohm speakers on an amp the resistance/load is 4 ohms. 
ii, When putting 2 8 ohm speakers on a bridged amp it's 2 ohms.

That is what i was taught.

Now is that 4 ohms total, 2 ohms each side of the amp, or 2 ohms total?

My main question is. 
When bridging, with 2 8 ohms, when we look at the amp spec sheet, do we take this into account or do we simply look at the 4 ohm?

The amp can run fine 2 ohms each side and 4 ohms bridged. Have they already taken into account as many people don't know to reduce the ohmage again or is 'ii' wrong anyway?
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markie View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote markie Quote  Post ReplyReply Direct Link To This Post Posted: 23 December 2017 at 8:26pm
2 x 8 ohm speakers in parallel gives a total impedence of 4 ohms whatever it's connected to. I think your confusing the amp specs with the speaker impedence.But when you're running is stereo/parallel mono each side of the amp is seeing an 8 ohm load.... the speakers are not in parallel, they are connected one to each side of the amp.

If your amp is quoted as 4 ohms per side then the speaker load should be min 8 ohms when in bridge mode.

You say your amp is fine @ 2 ohms per side, then bridge impedence should not be less than 4 ohms. Your 2 x 8 ohm speakers should be fine.

When you are in bridge mode each side of the amp sees 1/2 the total impedence load so as above 2 8 ohm speakers in parallel is 4 ohms total load, but each side of the amp sees 1/2 of that load so each side is running  with a 2 ohm load.

I probably haven't explained that very well, but doubtless there will be an adult along soon who will correct me.


Edited by markie - 23 December 2017 at 8:36pm
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JonB67 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote JonB67 Quote  Post ReplyReply Direct Link To This Post Posted: 23 December 2017 at 11:48pm
Wow. Quite a pickle. Markie is spot on.

2x 8r speakers in parrallel are 4 ohms regardless of if they are on a single channel or bridged.

If on a single channel then that channel has a 4r load.

If in bridge then the two channels share the load and see 2r each.

So in answer to your question, just look at the 4ohm bridged spec on the amps manual.

Edited by JonB67 - 23 December 2017 at 11:50pm
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mitchiemasha View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote mitchiemasha Quote  Post ReplyReply Direct Link To This Post Posted: 27 December 2017 at 6:37pm
Yes... Thank you. That clears it up for me. 
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