Strange noise floor problem. Impedance related?

[vocalvoodoo]

Here's the problem. I'm getting horrible hiss with my mics. Let me set the stage...

I've tested with the following pres. Safesound P1, Symetrix 528e and the Mbox 2 pre's with the following mics. Shure SM7b, EV RE-20, Cascade m20u condenser, Neumann BCM 104 condensor and a Cascade Fat Head ribbon. The hiss is MUCH louder than your normal mic pre hiss. When you add even a tad of compression, it gets so noisy that it's almost unbearable. A downward expander helps, but you can really hear the hiss when the expander is closing after soft passages. Now granted, dynamics have much lower output than condensers, but the noise being generated isn't because of that. At least I don't think so because even he Cascade gets this horrible hiss. I checked all connections multiple times, and they are correct. I'm using new Mogami cables and the SM7b and Safesound are pretty much new. The SM7 is a couple months old, Safesound is 3 days old. I've tried everything from power conditioners and voltage regulators (it was suggested that the problem could be caused by dirty electric or low voltage), to balanced and unbalanced cables, to different outlets, to just monitoring the mic input through the Safesound headphone jack with the computer and Mbox2 completely turned off. I was also suggested that an impedance mismatch could be the cause, which is the way I'm leaning now.

My vocal chain is.....mic>pre>RME ADI-2>Mbox 2 S/PDIF (clocked to the RME).

Every combination has the hiss. Except for the BCM 104! Until today when I brought it home from work to test, I was at my wits end, convinced I must have a problem with the power in my house.

With the exception of the Cascade m20u who's impedance I don't know (because it's not printed in the specs), the SM7b and RE-20 are rated at 150ohms and the Fat Head at 600ohms. Now the BCM 104 is rated at 50 ohms.

With all pres, the BCM is damn near silent. Especially with the Safe Sound. Could it be because it's impedance is lower?

Does anyone have any idea what is happening here? Can this be right? I produce a guys voice who uses an RE-20 into a Symetrix 528e, and his noise floor is WAAAY quiter then mine. His sounds as quite as the BCM 104 through my Safe Sound.

Any help is appreciated.

[daeron80]

If you've got an acceptible noise floor with the Neumann, then when you put the RE-20 in its place, and make no gain change nor any other change, you should notice no increase in noise level. When you turn up the gain to make the EV as loud as the Neumann was, you should notice only a small increase in system noise. If it gets a lot noisier, there must be something wrong with the EV mic.

[vocalvoodoo]

Hey Dave,

Thanks for the reply. Well, we have narrowed it down to a grounding problem in my house. That's for now at least. If you care to know, here is another discussion on this problem, and the apparent solution. What a pain! LOL

http://www.gearslutz.com/board/showt...d=1#post940883

By the way, I quickly glanced at your page. Good times with all the Doom stuff! That game was GREAT back in the day. Especially dialing into a friends computer and playing head to head.