I`m debugging an API 7600 of a friend, it have a strange intermitent noise. I was able to record the noise (I reduced the volume in the second 11) beware it could be loud, turn down the vol of your speaker.
http://www.soundclick.com/bands/page_songInfo.cfm?bandID=1116685&songID=9817738
here is the block diagram of the API7600
http://www.apiaudio.com/block7600.pdf
I test the controls and what I found is the noise is not in the preamp I move the gain and the noise didn`t change, also it have a preamp out the signal here is also clean. I can eq the noise so the problem is between the preamp output and the eq output or in the power supply(but why, if it is the PS the preamp should be afected :-\) the fx1 output is the eq output and the noise is present.
I`m trying to find a small allen key to remove the knobs and PCB to take a look.
I suspect of humidity, maybe a cold solder or a bad connector. If anyone have any other idea I would like to hear it.
best regards
Rafael
http://www.soundclick.com/bands/page_songInfo.cfm?bandID=1116685&songID=9817738
here is the block diagram of the API7600
http://www.apiaudio.com/block7600.pdf
I test the controls and what I found is the noise is not in the preamp I move the gain and the noise didn`t change, also it have a preamp out the signal here is also clean. I can eq the noise so the problem is between the preamp output and the eq output or in the power supply(but why, if it is the PS the preamp should be afected :-\) the fx1 output is the eq output and the noise is present.
I`m trying to find a small allen key to remove the knobs and PCB to take a look.
I suspect of humidity, maybe a cold solder or a bad connector. If anyone have any other idea I would like to hear it.
best regards
Rafael