low volume and hum using mic

[kozikowski]

I'm doing this on the fly, so it's a little rough and remember the address because nothing points to it yet.
http://www.kozco.com/tech/audacity/Docu ... _Specs.txt

With the idea you have to start somewhere, I said to bring the sound peaks up to standard.

I didn't use LF_rolloff on your clip. I went straight for Noise Removal, a good deal less aggressive than yours.

Then check and fix RMS. This is where you usually go around in circles. This step typically kills the noise specification.

Run Normalize again to put the peaks back and measure everything again.

It's still a violin because you have to know too much to do it, but it's a start.

Note: Smoothing controls how much of your voice Noise Removal ignores. I bet you have even sloppier sss sounds than I do with a value that large.

Koz

[Xerlome]

I've set the noise removal. Sounds good.

What is RMS?

I've never used normalize. Does that reverse the noise removal? Is it different from "undo" in edit?

[kozikowski]

Root Mean Square. It's a technical measurement of the force or energy of the blue waves. It also happens to roughly correspond to loudness, so it was a handy number even if it makes no apparent sense at all.

Normalize and Amplify are close cousins of each other. They both change the size of the blue waves. Amplify happens to tell you outright the difference between your peaks and 0. That happens to be one of the ACX specifications, so that's handy. Normalize has additional tricks over Amplify (separate left and right amplification for one thing), but Removing DC is handy. DC or battery voltage sometimes leaks into a show from defective sound equipment. It's not sound. It's pure evil and it screws up post production and editing.

The quiet portions of your show should always settle at 0. This is a bad edit caused by DC problems. Even tiny almost invisible ones cause troubles.



All Amplify and Normalize do is turn the volume control up and down as needed. They seem to run at odds with noise removal because when Normalize turns your voice up, the noise goes up, too. They can't tell content. They turn everything up.

Then you go and fix the noise which messes with either the loudness or the peaks.

On one of the posts I called it Whack-A-Mole processing.

Koz

[chris319]

Go to Control Panel -> Device Manager and look under Sound, Video and Game Controllers. Disable all audio devices if any except your ART Preamp. Make a test recording and see if there is hiss.

Next,

Go to Control Panel -> Sound. Under Recording, find your ART preamp and select Levels. Run the slider all the way down to zero and make a test recording. Do you hear any hiss?

I don't like this ART USB Preamp already. It only does 16 bits and is USB 1.1. I don't see a published signal-to-noise spec for it.

Right off the bat we can rule out that the hiss is coming from the SM58 itself.

[kozikowski]

Right off the bat we can rule out that the hiss is coming from the SM58 itself.

Yes. That's basically a shielded coil of wire sitting next to a magnet. Hard to make noise with that.
Koz

[chris319]

A lot of people like these, but I have never used one myself.

http://www.centrance.com/products/mp/

[kozikowski]

I have never used one myself.

That's important. I have a Shure X2U and I used it in the Audacity Overdubbing tutorial since it has (drum-roll) no latency monitoring as well as all the other features of the CEntrance unit.

However, I would not recommend one not because of any shortcoming in technical specifications or quality of sound. It will not get loud enough. I have never used it where I didn't have the microphone gain knob smashed up as far as it will go and I would have paid well to have another 10dB of gain or so. The "Spinal Tap" joke of turning it up to 11. And this is including an SM58, which is not a bashful microphone. I wrote to Shure and they said basically, "That's the way it is."

If you don't have the control of a full sound mixer and metering, the safest thing to do is perform low volume and I suspect that's a shortcoming to a lot of these products. That can make meeting ACX noise specifications entertaining.

Koz

[kozikowski]

The Centrance unit is out of stock.

Koz

[chris319]

The X2U spec says 50 dB gain and it's only 16-bit

I don't see a gain spec for the Centrance. At 24 bits you could run up the gain digitally.

[kozikowski]

Not if the analog noise floor is right there. If there's only 50dB between the unavoidable low volume and the native noise, It's still a 50dB serious problem no matter how many bits accuracy you have.

Koz