john_lenfr said:I want to know simply (because I'm not very good in English) what is the difference between the "Bridge" and "Parallel" mode.
(Especially for the LM4780 but maybe for other references too)
I read datasheet but I clearly did not understand.
You are right that the output voltage is effectively doubled, but this does not result in twice the output power. It results in 4 times the output power. P = V^2 / R. If V increases by a factor of 2, P increases by 2^2, or 4. This is obvious if you consider that when the voltage doubles (for the same load), the current doubles too.In a bridge mode configuration, two chips will deliver nearly twice the output power as a single chip because the output voltage will swing twice as far (as the output of one chip goes in the positive direction, the other chip goes in the negative direction).
And if I have a 6 ohm speaker?
Of course you have to realise that you can't break the laws of physics and get say 240 W out of two chips each capable of 60 W each.
I think you misunderstood something! The LM4780 can deliver 120W, look into NS specs!
The total thermal loss in bridgemode is higher, the chip prduces more heat in that mode. This is always a problem in a A-class amplifier (ok, AB-class).
The problem is to handle so much heat energy with matching heatsinks. You're in need of a fan at such a design (power controlled so it only runs in highpower consumption).
Ha, that's he same problem i had. I decided to test the parallel mode ampmodule made by Peter Daniel,
maybe i try the bridged mode module later on (from jackinj).
Normally the bridged module produces less distortion than the parallel one. But this is only in upper end where the amp runs to its limit.
In my opinion it's better to take the parallel version because you often have speakes with lower impedance, even if the manufacturer says they don't have lower impedance. Aso it could be that you'll change your speaker sometime...
Simply, Yes. It is dangerous.So I want to know if it is dangerous to have 6 ohm speaker on a LM4780 in bridge mode?