Boombox on wheels needs an experts trouble shooting skills!

[jestah]

Tried to connect all the grounds to a single point (the ground input from the audio cable is where they all join for the moment as on my test bench there is no case to ground) but there is still a hum.... Maybe the resistance is not even, could some one explain how i test this with my mm? Can i rule out my soldering of my amp kit as it sounds fine on a battery?

What other test can i do with my mm to help narrow the cause of my hum down with?

Could a mod move this to the chip amp section?

[col]

I started with a kit that used two TDA2004 chips bridged to get 15w of power (loud enough but a little too much distortion at high volumes) and will be moving to a tripath based amp soon (thinking of the 100w from sure electronics so i can run a very clean sound at low power)

I received my Sure Electronics 2 X 100W yesterday. Iv'e added a bit of aluminium to the heatsink changed the input caps to 2.2uF and plugged a 19v 3.5A laptop psu onto it. It rocks! Very simple, safe (as safe as a laptop anyway) and sounds great and it only cost AUD$51 including postage

col.

[jestah]

Thanks for info about the sure boards and your right, at that cost i can afford to have some decent sound from a boom box that see some rather decent abuse....

Sadly tho i have made the call that i need to finish this project safely before i move on as i have a gift for leaving projects mid way. This cant stop me thinking about my next set up... maybe keep your eyes posted on the speakerbox pages :>

So where am i at with this project, well im going to go out and see if i can get my hands on a wall wart or laptop psu and see how noisy that is as my only guesses now are unbalanced ground lines (where do i probe as my reference, i want to go to the negative side of my battery but that's rather lacking