STS Audio
01/09/2026
This Behringer mixer used as a bench monitor controller and mic pre developed a nasty crackling noise on both mic channels. Having previously replaced the Op-amps and with no schematics available, I though this would be an impossible repair, however....
Probing around with a multimeter revealed a 'leaky' high resistance across parts of the black goop used to secure the resistors. Some of the resistors were open circuit, possibly a result of the goop turning acidic. After removing the goop, repairing lifted tracks and replacing open resistors, all is well and the mic channels are no longer crackling.
Success - time to clean the pots and switches.....
This Behringer mixer used as a bench monitor controller and mic pre developed a nasty crackling noise on both mic channels. Having previously replaced the Op-amps and with no schematics available, I though this would be an impossible repair, however....
Probing around with a multimeter revealed a 'leaky' high resistance across parts of the black goop used to secure the resistors. Some of the resistors were open circuit, possibly a result of the goop turning acidic. After removing the goop, repairing lifted tracks and replacing open resistors, all is well and the mic channels are no longer crackling.
Success - time to clean the pots and switches.....
06/10/2026
AKG C3000B Microphone in for repair - a nice, affordable condenser mic with a rather loud 50Hz mains hum!
Cracking this one open revealed a fundamental issue in that the physical contact between the grill and the case was intermittent, thereby not providing a reliable ground connection to shield against interference and hum.
Quick and easy solution was to solder a couple of ground runners down to pin 1 of the XLR as per the yellow wires in the photo.
AKG C3000B Microphone in for repair - a nice, affordable condenser mic with a rather loud 50Hz mains hum!
Cracking this one open revealed a fundamental issue in that the physical contact between the grill and the case was intermittent, thereby not providing a reliable ground connection to shield against interference and hum.
Quick and easy solution was to solder a couple of ground runners down to pin 1 of the XLR as per the yellow wires in the photo.