Line mic noise preamp USB hiss eliminate how?

Question

Level 1

97 points

Line mic noise preamp USB hiss eliminate how?

Setup: Garageband 08, Tube MP ART project Series USB preamp, and a professional-grade non-powered ribbon mic. There is a dedicated booth for the mic.

The preamp gain needs to be turned way up to get an acceptable but seemingly-low recording level from the mic into GB.

So the preamp is set at +35dB gain (max is +45dB) and the optional gain booster of +20d is enabled. The preamp functions Impedance, Filter, Phantom, Limit, and Phase are disabled. (I know that Phantom power should not be used with the mic I have.) High quality shielded mic cable.

On playback, I can here a noticeable difference - there is silence between the gaps of spoken words - there is "noise" under the spoken parts. It is not room noise.

I can use Bias' SoundSoap (or play with the Noise Gate plugins I have installed) but to totally eliminate the noise, both the above effects muffle the sound and it can also sound out of phase.

How can I maintain a clear recorded voice that does not have that noticeable difference between the gaps of the spoken parts?

There's so much information out there yet I can't find an answer for non-technies.

Dual 2 Ghz PowerPC G5, Mac OS X (10.5.6), RAM 3GB; HD 860GB; Safari 3.0.4;

Posted on Apr 10, 2009 3:25 AM

Reply

Answer 1

Apr 10, 2009 7:22 AM in response to yattaman

yattaman wrote:
Setup: Garageband 08, Tube MP ART project Series USB preamp, and a professional-grade non-powered ribbon mic. There is a dedicated booth for the mic.

How can I maintain a clear recorded voice that does not have that noticeable difference between the gaps of the spoken parts?

There's so much information out there yet I can't find an answer for non-technies.

The short answer - use a different mic.

Your mic does not sound compatible with that preamp (or there could be something wrong with the mic). You could try changing the impedance on the preamp, but that will likely not be enough. Ribbon mics often require preamps that perform differently than the one you have. Instead of chasing down the perfect preamp (although you could try that too), you might want to use the kind of mic your preamp was designed to amplify, e.g. a standard condenser.

Reply

Answer 2

yattaman Author

Level 1

97 points

Apr 11, 2009 9:46 PM in response to MattiMattMatt

MattiMattMatt wrote:
Your mic does not sound compatible with that preamp (or there could be something wrong with the mic). You could try changing the impedance on the preamp, but that will likely not be enough.

I double-checked the preamp manual and it states in several places that a ribbon mic can be used with this preamp.
I will experiment with the impedance and other options on the preamp front. It's a new Nady mic, the flat circular one. Obviously, with music under the finished project, I can use this mic. But a dry read suffers at the moment.

Reply

Answer 3

Lust

Level 3

515 points

Apr 12, 2009 7:51 AM in response to yattaman

Well lowering your input impedance should help sonically with a ribbon but...

...what you have described sounds like there is not enough gain to push the ribbon. Ribbons typically are not very sensitive mic's and need a fair amount of gain.

Although the Tube Art MP says there is plenty of gain.

But what puzzles me is this:

{quote:title=yattaman wrote:}On playback, I can here a noticeable difference - there is silence between the gaps of spoken words - there is "noise" under the spoken parts. It is not room noise.{quote}

Do you have a way to use another interface?

As an aside Phantom Power itself will not hurt Ribbons. The issue is if pin 2 or 3 were to short to ground with Phantom Power on.

I've left Phantom Power on many times with ribbons.

Reply

Answer 4

yattaman Author

Level 1

97 points

Apr 13, 2009 11:32 PM in response to Lust

**** wrote:
Well lowering your input impedance should help sonically with a ribbon but...

The button on the preamp is set on "high".
The mic specs says the mic impedance is <=200 ohms
<div class="jive-quote">But what puzzles me is this:

{quote:title=yattaman wrote:}On playback, I can here a noticeable difference - there is silence between the gaps of spoken words - there is "noise" under the spoken parts. It is not room noise.{quote}

Do you have a way to use another interface?
Only this preamp. Is the trouble with the USB Codec? I think I once saw a way to bypass the USB Audio Codec used by the preamp, and instead use the Mac "line in" setting while still using the preamp. Change the settings in the Sound Preference pane and/or Audio-MIDI Setup? Also, regarding Audio-MIDI Setup, no matter what I try, cannot make the 48000 setting stay enabled in Audio-MIDI Setup on the left side. It always reverts to 44000. I saw a thread here about it a year ago, and I guess this was never solved.

As an aside Phantom Power itself will not hurt Ribbons. The issue is if pin 2 or 3 were to short to ground with Phantom Power on. I've left Phantom Power on many times with ribbons.

The Nady manual (from here: http://www.nady.com/RSM4micspg.html) says phantom power will destroy the ribbon in this mic.)
How about this:
I decrease the preamp mic gain, and increase recording level in GB. And, can you confirm how to increase the recording level in GB? :-|

Reply

Answer 5

poflynn

Level 4

1,303 points

Apr 13, 2009 11:54 PM in response to yattaman

I decrease the preamp mic gain, and increase recording level in GB. And, can you confirm how to increase the recording level in GB? :-|

You don't when using an interface. The level is set externally.

Reply

Answer 6

yattaman Author

Level 1

97 points

May 31, 2009 5:05 AM in response to yattaman

The noise floor/gain issue was due to the use of a ribbon mic with an underpowered pre-amp. I changed to a Rode condenser mic that also uses phantom power, and everything is fine now.

Reply