chipamp.com LM1875 Hmm

[pclements]

I constructed a LM1875 kit from chipamp.com. I assembled and tested it per the instuctions listed here on DIYAudio.com.
http://www.diyaudio.com/forums/showthread.php?s=&threadid=122793

The PSU tests OK, correct DC voltage. I measure NO DC-offset at the amp output. When connected to my system it produces only a loud hum and no music. I've checked everything I can think of, but find no discrpencies between the as-assembled amp and the instructions.

Anyone have any suggestions? Further testing I should do?

Thanks,

 

[pacificblue]

Pictures?

 

[mjf]

hello.
no dc-offset? there are mostly a few milivolts of offset.........
perhaps check the input for a missing or wrong ground connection,cable failure or so...........
greetings.............

 

[peranders]

If you take your DVM and measure the resistance between signal ground, speaker ground and power ground, are they connected?

Brian, don't you have schematics over your design? Doesn't your cad program support that?

 

[fr1s]

I constructed a LM1875 kit from chipamp.com. I assembled and tested it per the instuctions listed here on DIYAudio.com.
http://www.diyaudio.com/forums/showthread.php?s=&threadid=122793

The PSU tests OK, correct DC voltage. I measure NO DC-offset at the amp output. When connected to my system it produces only a loud hum and no music. I've checked everything I can think of, but find no discrpencies between the as-assembled amp and the instructions.

Anyone have any suggestions? Further testing I should do?

Thanks,

I have same problem :/

 

[audio1st]

Please give info on, C1, C2 and R6 values used.
Remember these locations must be bridged (jumped), if you choose to omit them..

 

[pclements]

Fixed IT!

Thanks for the suggestions... My R6 jumper was the problem. Now everything sounds AWESOME. It runs hot, but I'll get that fixed.

Thanks for the help.

-Patrick-

 

[Comitex]

may i ask how much power can you get from this amp ?

 

[Stixx]

Just google for LM1875 and there you are...
20W into 4 ohms
😉

 

[Luck]

Hi,try to use +/-28V if your heatsink is big enough.... you will hear a differnce sound compare with your +/- 25V system.