OK that's helpful. It's not so much that the preamps are noisy, but more that the ribbons have such a low output that I have to increase the input trim so much that it raises the noise floor.
That's really a contradiction. The noise floor consists of 2 components- self noise, which is generated by components in the signal chain, and ambient noise, which comes from the environment, often called "background noise". If your problem is self noise, the problem may be from inferior components, which produce a lot of noise on their own, from gain staging errors, or from external electrical sources, as with RFI (radio frequency interference) or improper grounding (ground loop hum). In the case of self noise, adjusting gain staging can help. If the problem is cranking up cheap preamps because of the low output of dynamic/ribbon mics, then switching to a condenser with higher output and turning down
the preamp gain will often improve things dramatically. If the problem is ambient noise, messing with gain staging doesn't do much. If you switch to a condenser, you'll get a hotter signal, but the ambient noise will also be louder- no benefit. If ambient noise is the problem, you basically have 3 options: 1- turn down the gain and get closer to the mic, so the source makes up a greater percentage of the signal. With directional mics (cardioid/figure of 8, etc.), this will increase "proximity effect". In other words, bass will be boosted as you get closer to the mic. Omnidirectional mics don't produce proximity effect, so you can get real close to the mic without increasing bass. For this you will need a real good pop filter, maybe even 2, or you'll have trouble with aspirated consonants, especially "p", which will produce "pop" from the puff of air you blow out when you voice the consonant. 2- get rid of the damned noise. Turn off refrigerators, furnaces, sump pumps, pool timers, fluorescent lamps, etc. 3- When you *can't* get rid of the noise, increase isolation. Put *mass* between the mic and the noise. Build a vocal isolation booth, or at least use a reflection filter, which is a start. Get that CPU and its damned fan out of the room!
In some cases, if an ambient noise source is in a fairly constant frequency range, such as a humming fluorescent lamp, you can use creative EQ or noise reduction programs to attenuate that specific frequency. Most noise, however isn't like that. Police and fire sirens are the worst, because they oscillate through a wide band of frequencies. In the end, getting rid of ambient noise is always better than trying to deal with it once you've recorded it. This usually means finding a better room, or isolating the one you are stuck with.
I hope that helps. So- what is your problem, really? Self noise, ambient noise, or both?