Best Chip amp for powered PA speaker?

[clemon]

Hi all,

I'm working on a design for a powered PA speaker, and would like to poll the forum for opinions as to the best chip amp to use.

My goal is to create a nice compact unit to fit into one of my speaker cabs. It should run 100+ watts into a 4 Ohm load (pair of 8 Ohm cabs in parallel). I'd also like to build in 2 switchable mic/line channels.

I'm currently looking at the LM833 to build lo-z to hi-z converter, preamps and tone controls for each input channel. I'm on the hunt for a compatible mixer circuit.

I'm debating between the LM4780 in parallel (120W@4 ohm), and the LM4651/2 (170W@4 ohm) amplifier circuits.

Any thoughts/suggestions/warnings for either of these designs? Is there another amplifier I should be considering? Alos if anyone out there has any schematics for the mixer portion of my plan, I'd love to see them!

Thanks much.

[officeboy]

What you are proposing shouldn’t' be too hard. But the LM4651/2 isn't really a chip amp (in the typical sense) and I don't know if anyone here has even used one. (LM4651/2 is that national Class D amp)
The LM4780 should work well, as long as you can work with all the little pins. If you don't want to make a PCB then I'd suggest a pair of LM 3886's or LM3875's.
Either one will get you in the 160W range (parallel into 4 ohms) with a 30Vac power supply.
As long as your transformer has 22Vac or higher secondaries you will be able to get over 100w.

[troystg]

Hey-

Steve @ Apex.jr has this amp which is 25x2 into 8 Ohms.

But what is intresting about it is that it has 2 sets of RCA's AND a mic input.

http://www.apexjr.com/Dual25FR.html

Also, PE is currently running a sale on their in spkr PA amp for $119.

I am debating the purchase of one myself.

http://www.partsexpress.com/pdf/flyer04/018pe4d.pdf

http://www.partsexpress.com/pe/pshow...797&sf=04d-018



Thanks,

Troy

[clemon]

Thanks guys. I'll download the specs on the 3886/3875 chips and have a look-see.

I'll also be checking out the mic/line in arrangements for the apexjr.

Thanks also for the power supply info. I'm still a bit hazy on the claculations required to come up with a good psu, so thanks for the numbers!