Chip amps for 5.1 system?

[Karanael]

Hello all,

I'm looking at building a nice shiny 5.1 surround system for a computer (Advanced Physics projects are great, as long as you can justify your project...) using a folded horn (with a 8" or 10" driver?) for the subwoofer, and some reasonable sealed satellite units.

For this project I am looking at using some reasonably cheap chip amps, with power handling in the range of 30-40w for each satellite (maybe more for the centre?), and a nice and chunky 100w+ chip for the subwoofer.

What chips would best suit this sort of power handling?

The power supply is likely to be internal, a 200VA (?) tordorial and some nice big capacitors, and the compartment for the amplifiers is going to be about 10" tall, by 10" wide, and about 3"-4" deep. I am looking to put a nice big heatsink over the top of the board, as to allow air to flow up over it (aided by an 80mm fan, perhaps), anyone see anything wrong with this idea?

Thanks for your help

Karanael

[Beggar]

Hello

I guess you have a few choices here, for the sattellites you may want to look at the BrainGT LM3875 based kits, they would certainly be good, or indeed skip the kits altogether and make your own pcbs or point to point wire them.

I recently used a p2p wired LM4781 for 3 surround channels (its a 3 channel chip) and found it to be a most excellent amplfier, i have also heard favourable things of the LM4780, so maybe a single 4780 chip for front left and front right, and a LM4781 for C-RL-RR (does centre really need more power?)

As for the sub you may want to look into LM4780 parallel / bridged combinations, the LM3886 also works very well bridged as it drives 4 ohms in single mode very well, translating to a good driver of an 8 ohm load in bridged mode.

As for your power supply, you might want to read more about the concept that is 'gaincloning' as you mention large caps this is kinda at odds with the concept (although for the sub i think larger caps are a good idea) Also i would recomment more than 200VA for such a large number of amps, might want to think about using a couple of 300VA or so unitis, maybe giving the sub its own dedicated transformer, anyway thats just something to think about

I've built something very similar over the last couple of months, but mine was primarily for stereo use, with 5.1 capability as a 'side order' as soon as i get some knobs and generally finish the thing off ill post some pics.

Generally my adive would be not to rush into this project and 'design the cr*p' out of it before you build it as so many amps in the same chassis can get complicated.

Good luck!

Nik