lm3875, dc on input ?

[Jaap]

I just finished my first LM3875 chipamp.
It works with a clipleaded potmeter between amp and cdplayer.

When I put a preamp between the cdp and the chipamp I hear a lot of very loud noise. Could it be that there is a little dc on the output of that preamp and that the chip doesn't like that ?
I have no problem connecting that preamp to a tubeamp.

[pacificblue]

Originally posted by Jaap
When I put a preamp between the cdp and the chipamp I hear a lot of very loud noise. Could it be that there is a little dc on the output of that preamp and that the chip doesn't like that ?

Could be, but you would have to describe what noise it is. If DC and produces very loud noise, than there must be a lot of it. Can you measure that? Disconnect your speakers first so as not to damage them.

It could also be the classic ground loop. That would be a hum (or buzz) that you would recognize, because it sounds similar to the sound you hear, when you pass one of those big transformers of electricity suppliers.

How does the amp react, if you connect the cdp directly?