Help understanding functionality of class d boards on ebay


2010-09-28 2:52 pm
Hi all, I've got three projects in the works and having a little trouble understanding what will suit my needs best -- wanna start with a couple pre-assembled pcb amps, mostly looking on ebay (unless someone has a better source to recommend) .. Cost is an issue as I do want to create some usable gear, but I'm building these projects mostly as a learning experience so I don't want to invest in anything that's gonna cost me an arm and a leg until I have a little more confidence with what I'm doing.

First project is to turn a cheap PA speaker into a powered speaker.

Q1- Most of the amps on ebay are stereo but I only need one channel. Am I better off finding a mono amp or just getting a stereo one and only using one channel? Is a single channel board likely to be less expensive or is the difference going to be nominal in the end?

The other two projects both involve these 2.1 amps I'm seeing (example: TDA8950TH 2 1 Digital Class D Amplifier Board 2 150W 250W | eBay )

Q2- Is this essentially just three amplifiers on one board, or is there usually some kind of crossover matrix involved for the "sub" channel? Like could I potentially use the 250w channel to power a floor monitor and the other two 150w channels to run small PA speakers? Or would the floor monitor just be getting the lower frequencies?

Q3- I can't seem to figure out what all those pots are for from the description. 5 knobs, I figure volume for the "sub" channel, volume for the two stereo channels (or perhaps one for each channel?), then what? Is there some equalization on there, or...?

I tried contacting the manufacturer of a different board last week and the response was such broken english that I thought this might be a better place to get a handle on these things.

Thanks for any and all help/thoughts/advice/etc