I am getting almost a flat line (no volume) when I use USB input from TubeMP with +20db gain button and gain set at 24, output at -8; any more and I get too much noise. The level indicator on TubeMP is going up to yellow = 0db. What is wrong?
Is the level meter going up to yellow all the time, or just when you talk?
Which Computer?
Koz
Do you have the right recording input set in Audacity’s Edit → Preferences → Audio I/O menu?
Thanks to both replies. 
Audacity is set to “USB Audio CODEC” per Tube MP manual. Same on Wave Pad. They both record, just with low level. If I crank the MP, I still get pretty low signal with more noise.
I am using a E-V 257 mike, which my wife (jazz singer Spider Saloff – http://www.spiderjazz.com) has used in performance for years with no problem.
Re the LEDs – If I project with “announcer voice,” I can get the LED’s on MP to hit yellow (0db); if I actually shout (almost eating the mike), I can hit red. With a “conversational delivery” (which I prefer) I am lucky to get the first Tube MP LED to light (-15db), although at times I might even get the second (-7db) to light briefly.
I have these buttons lit (which means “on” I presume):
+20db Gain - low impedance - filter on - and tried Limiter both on and off.
I believe the E-V 257 has 300 ohm impedance.
With the Gain at 18 and Output at -8, I have low noise and low volume. I can crank it to about 24 gain and +1 Output before the noise gets really bad; volume is better, but still too low.
I am trying to borrow a Shure SM 57 or 58 to see if that helps.
It looks like that mic is a dynamic mic, so you shouldn’t need phantom power, but the only info I could find is from eBay, so are you sure you don’t need phantom power for that mic?
Applying phantom power to a mic that doesn’t need it isn’t dangerous.
If that doesn’t help (and I don’t think it will), then my next guess is that there’s something wrong with the mic, mic cable, or the TubeMP.
A Voice Over friend suggests I try a condenser mic and is willing to loan me such. This should give more gain, along with picking up more room noise. Oyyyyyy! 
FYI, the level problem seems to have been miraculously “solved” for now – but a mysterious hummmm has appeared in its place.
(definitely associated with the E-V mic, not the cable, that I’m using). 
I cannot think of anything I am doing differently, except perhaps unconsciously speaking louder and/or closer to the mike. The new problems is POPping P’s. Actually, an old problem. 
Thanks for your suggestions. I agree that it is probably a fritzy problem with the mic – one that doesn’t show up under live performance conditions.
(fyi, I’ve tried unplugging, etc, about ten times; and this happened before and went away.)
Or… it might be a fritzy problem with the narrator (me). 
I’ll keep on a’tryin’. Thanks again. And drop a note if you think of anything more.
Bobcat
Three of those issues you mentioned lead me to believe it’s the mic cable.
And the problem with ‘P’ sounds (aka plosives) is due to the lack of a pop filter on the mic. Usually when you use a mic live, the mixer has a 100Hz low cut filter applied that deals with plosives pretty well, but you don’t have the same luxury in a recording setting, so you should use a pop filter.