Bridging AMP causes BOOM (help please)

[styxx]

A mate has 400wat car amp. 2 x 200watt apx. (running 2 subs)
He has bridged both channels to "Get more power to the subs".
The problem is that now he is burning out fuse wire like hell, including the very short and fat one I put on, and blowing fuses.

Why bridge 2 subs? 2 channels? Why?
I can see why when there is 1 sub on one channel.

He tried to fix by just putting in a 40amp fuse instead of the standard 30amp. But he wouldnt listen when I said there was a reason why it was blowing.

Im aware that this will drastically change the ohmage.

So basically:

1. Is he wasting his time bridging a 2 channel amp with 2 subs in parallel ?
2. Why would this cause burnouts and blowing fuses?
3. Is there a fix for this if bridging it is not as stupid as I think?
4. Please offer any info towards this problem. Thanks

[sreten]

So basically:

1. Is he wasting his time bridging a 2 channel amp with 2 subs in parallel ?

Almost certainly. Assuming subs are 4 ohm and each channel is
rated down to 2 ohm normal use - rating for bridging would be
4 ohm load - sounds like its two.

Resistive losses in the amplifiers will be serious, so its likely
that barely more power is being delivered to the subs.

2. Why would this cause burnouts and blowing fuses?

The power supply is drawing loads of current but the power
isn't being transferred efficiently to the load by the amplifiers.

3. Is there a fix for this if bridging it is not as stupid as I think?

The amplifiers would need to be rated for 1 ohm loads
per channel to effectively drive 2 ohms in bridge mode.
(i.e 200w into 1ohm, 100w into 2ohm, 50w into 4ohm)
So bridging is unlikely to be a good idea in this case.

4. Please offer any info towards this problem. Thanks

sreten.

[Immo_G]

It is very rare to find anything short of competition grade that can handle 2 ohm loads when bridged. Most amps that bridge handle 4 ohms at a hotter temperature, and they can blow/overheat quite easily doing it (i've fixed 2 from this, and no i didn't kill them). To try 2 ohms would be a quick death to most amps.

Best bet for a 2 channel amp and 2 x 4 ohm subs is running 1 channel per sub, 200 watts, so probably 80-100rms, would be ok for normal use, as long as they weren't pushed extremely high.

Else build a B/P gainclone, 335 watts rms into 4 ohms, one of those per sub would do nicely

[SkinnyBoy]

the amp would have to drive less than an ohm per channel under certain frequencies... poor amp..

let him kill it... lol

the amp would really have to be rated to half an ohm per channel for it to be truely happy....

[nicodelosrios]

look the impedance to voice coil in the manual may be is 4hom in this case the amp work good but if the coil are less to 4 hom tha amp work very hot and demand much current.
check with the amp work to voice coil impedance at brifge and look the correct wire to power and gound and correct contact if you want send me the references and i study wath happend.
sorry my english.