Bridged Amps - Quick Question

I've been trying to teach myself, and I'm just making sure I've got this right so far.

My setup = 2 DVC 4 ohm subs
Amp in example = 650W x 1 @ 4O, 1200W x 1 @ 2O, 2000W x 1 @ 1O

Say I have 2 amps rated at 2k RMS @ 1 ohm each. This means their output is 4k @ 2 ohms bridged, and each amp would be seeing a load of 1 ohm each. If I were to wire my subs at 1 ohm, the amps would see a load of 0.5 ohms and likely fry. So my only option would be to wire at 4 ohms. Does this mean that each amp sees a load of 2 ohms, and the final output would be 2400W at 4ohms? Which makes sense because each sub would be seeing 1200W at 2 ohms if wired individually.


On another note... if someone locally wants to trade 2 DVC 2 ohm XFLs for 4 ohm in the future... Contact me ;) I doubt my current electrical would support 2 2kw amps running at 1 ohm though...

You say "bridged" do you mean "strapped"?

Make/model of amp(s)

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Originally Posted by keep_hope_alive

You say "bridged" do you mean "strapped"?

Make/model of amp(s)

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US Amps Merlin M3D3. It seems to be stable enough at .5 ohm, but I wouldn't want to do that daily anyway.

And yes I meant strapped. Bridged is essentially the same definition, I guess that name is just not as commonly used for this purpose

you got a manual for that thing? i think strapped at 4 ohms is your best bet.

I haven't bought it yet, this is sort of a preliminary question. I found one real cheap locally that's pretty beat up but still works, and another in better condition with manuals and the original packaging and everything.

And strapped at 4 ohms would work great anyway. It would be slightly more efficient than 1 at 1 ohm, output a little more, and give me a ton of power if I decide to compete somewhere down the line.

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Originally Posted by keep_hope_alive

you got a manual for that thing? i think strapped at 4 ohms is your best bet.

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I second this. I'm not a big fan of running below rated impedance no matter how many other people have done it successfully.

Why not just buy 1 large mono that does power at 1 ohm?

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Originally Posted by Chriszle

Why not just buy 1 large mono that does power at 1 ohm?

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It's more efficient and gives me more options down the road. I'm going to be getting a new car some time this summer so I'll probably change the subs out and run 4k@ 2 ohms.

Also I can get 2 of them for about $450... Good luck finding a good 4k that does rated and puts out clean power for that

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Originally Posted by Tenacious

It's more efficient and gives me more options down the road. I'm going to be getting a new car some time this summer so I'll probably change the subs out and run 4k@ 2 ohms.

Also I can get 2 of them for about $450... Good luck finding a good 4k that does rated and puts out clean power for that

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actually its not, you got two amps drawing power instead of one amp creating the same power with the same circuit, it can make a big difference in amp draw.

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Originally Posted by TitoThePirate

actually its not, you got two amps drawing power instead of one amp creating the same power with the same circuit, it can make a big difference in amp draw.

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Two amps drawing 1200 @ 2 ohms for a final load of 2400 @ 4 ohms is a little more efficient than one amp drawing 2000 @ 1 ohm according to the efficiency ratings. I'll probably have it set with a DMM to output 2000 @ 4 ohms which will make it even more efficient

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Originally Posted by Tenacious

Two amps drawing 1200 @ 2 ohms for a final load of 2400 @ 4 ohms is a little more efficient than one amp drawing 2000 @ 1 ohm according to the efficiency ratings. I'll probably have it set with a DMM to output 2000 @ 4 ohms which will make it even more efficient

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OH. in those terms yes. it can be.

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Originally Posted by TitoThePirate

OH. in those terms yes. it can be.

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Yeah, I see where you're coming from though.

It is not more efficient. It may be easier on the amp but 2 amps with power supplies will draw more than a single amp at 1 ohm. I am an electrician its simple math. its like having 2 60 watt light bulbs saying it draws less than 1- 100w true its more power but also a bigger load on electrical system.

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Originally Posted by tommydh

It is not more efficient. It may be easier on the amp but 2 amps with power supplies will draw more than a single amp at 1 ohm. I am an electrician its simple math. its like having 2 60 watt light bulbs saying it draws less than 1- 100w true its more power but also a bigger load on electrical system.

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These amps are 76% efficient at 1 ohm and 84% efficient at 2 ohms.

So...
1 amp pushing 2000w @ 1 ohm = approx 191 amp draw at 13.8v
1 amp pushing 1200w @ 2 ohm = approx 103 amp draw at 13.8v
2 amps strapped pushing 2400w @ 4 ohm (each amp seeing a 2 ohm load) = approx 207 amp draw at 13.8v
2 amps with gain set to 2000w with DMM with same setup as last calculation = approx 172 amp draw at 13.8v <---

You may say this isn't a lot of difference... but 175a is the max fuse rating I can use to stay in my current class in MECA SPL competitions, so it actually makes quite a bit of difference in my case.

efficiency is a moving target that decreases as the amp gets hotter.

this fuse BS is why I say all classes should require clamping amps. pretty easy with modern split-core C.T.'s or logging clamp meters.