Bridged Amps - Quick Question

[Tenacious]

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 //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif I doubt my current electrical would support 2 2kw amps running at 1 ohm though...

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[keep_hope_alive Premium Member]

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

Make/model of amp(s)

 

[Tenacious]

You say "bridged" do you mean "strapped"?
Make/model of amp(s)

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

 

[keep_hope_alive Premium Member]

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

 

[Tenacious]

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.

 

[Spooney 10+ year member]

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

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

 

[Chriszle 10+ year member]

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

 

[Tenacious]

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

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

 

[TitoThePirate 10+ year member]

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

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.

 

[Tenacious]

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.

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

 

[TitoThePirate 10+ year member]

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

OH. in those terms yes. it can be.

 

[Tenacious]

OH. in those terms yes. it can be.

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

 

[tommydh 10+ year member]

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.

 

[Tenacious]

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.

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.

 

[keep_hope_alive Premium Member]

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.