bridging gainclone lm3875 type amps

[jamie1107]

hi
i have just built 4 gainclones for a couple of systems and they sound great i used the pre made pcb s from chip amp . com and the lm3875 chips all fine what i want to do next is bridge 4 or g of those to gether for each channel of a power amp i have seen some people have done this before but i cant find any info on the builds anyone have any ideas i see one of them uses a ballanced line driver on the input is this overkill or nessacary when bridging chip amps
any info would be good
many thanks

 

[Puffin]

Have you looked at this :-

http://www.national.com/an/AN/AN-1192.pdf

There may be one specific to the LM3875. I used this and have just finished a pair.
I see the pin outs are different but it should work for teh LM3875. I dont know if balanced connection is neccessary.

 

[BWRX]

An inverting and non-inverting input buffer will give you the signals needed for each half of the bridge and will provide a good low impedance drive for the LM3875 chips.

 

[ionomolo]

LM3875 is not rated to drive 4 ohms loads and should not be bridged without paralleling too!