I got my USED Trident S40 mic preamp and have been playing around. I really like it, but have a question about some buzz. Here's the scenario:
- Gating the signal at -63dB from within my DAW gets rid of the buzz.
- With NO input cables plugged in, if I turn the gain up it's relatively quiet (small amount of speaker static type noise). With the input gain over +45dB and the output gain at +5dB or more, the preamp begins to produce electrical noise, but I'm thinking that's fairly high gain.
- Plug the XLR cable in (no mic attached) and I get buzz (probably RF noise) at lower gain. Insert 48V phantom power and it gets a little worse.
- Attach a microphone to the XLR cable and the buzz significantly reduces, but is still noticeable with high gain settings.
- Using the instrument input (built-in DI) on the front panel produces the same as above.
- Hovering my hand centered and over the top of the amp increases the buzz significantly, but touching the amp chasis almost eliminates it completely.
- Adjusting the knobs increases the buzz and creates a frequency-sweep type hum when adjusting. I'm assuming this is due to the fact that the knobs are metal and transferring the voltage from my body (just a guess)??
- If I use my DI box and connect to the XLR input I can literally crank both input and output gain and the preamp is dead quiet.
- The buttons for EQ in, comp in, etc. all make very insignificant crackle when engaging/ disengaging, but I'm thinking this is fairly normal.
Do I have a grounding problem, does the preamp just need a good cleaning or is there some other problem? I shut off all my other equipment except my A/D converter and Mac, but it made no difference. Should I record the sound it's making?