Tweet
Recently, I plugged a tube mic into one of the DIGI 001 mic pres. The mic/power supply cable that came with the mic had been wired improperly (perhaps applying 250V where it should not be). Ever since doing this, the following problem has appeared:
- The gain of the DIGI 001 mic preamp has been reduced 50%
- Turning the phantom power on or off produces a terrible crackling/hiss noise that dies down over a minute or two.
Initial troubleshooting notes:
- The phantom power crackle is happening before the gain pot
- The DIGI 001 uses combo jacks--balanced & 1/4"--and I believe it has separate gain stages for each. The 1/4" high-impedance preamp has no loss of gain
- The other mic pre (Input 2) is fine. It shares phantom power with Input 1, and does not have the crackle/hiss noise.
Without a schematic, my intuition says that I should start replacing components--all electrolytics and ICs in that first gain stage. My intuition gets me in trouble sometimes, and I'll be needing a magnifying lens to work on that PCB, so I thought I'd run it by some other minds first. Any "input" is appreciated.
- The gain of the DIGI 001 mic preamp has been reduced 50%
- Turning the phantom power on or off produces a terrible crackling/hiss noise that dies down over a minute or two.
Initial troubleshooting notes:
- The phantom power crackle is happening before the gain pot
- The DIGI 001 uses combo jacks--balanced & 1/4"--and I believe it has separate gain stages for each. The 1/4" high-impedance preamp has no loss of gain
- The other mic pre (Input 2) is fine. It shares phantom power with Input 1, and does not have the crackle/hiss noise.
Without a schematic, my intuition says that I should start replacing components--all electrolytics and ICs in that first gain stage. My intuition gets me in trouble sometimes, and I'll be needing a magnifying lens to work on that PCB, so I thought I'd run it by some other minds first. Any "input" is appreciated.
Comment