Care to post a sample?

You could use the Paragraphic EQ from the XF to notch the audio at whatever frequency the hum lies at.

There is a preset using four stacked filters notched at 60Hz that you can use as a guide

John

"HUM IN THE AUDIO. While generally not a problem in noisy recordings, in quiet recordings it is horrible. There is only one adjustment on the mic, high-pass filter on/off, but that doesn't fix it."

Even though on manual, your camera may have limiting that lets the noise floor rise in quiet spots. Make sure your audio peaks do not hit the limiter.

"I don't know if it is a 60Hz hum or what."
You need to know this first. Open the audio in Sound Forge and use Spectrum Analysis to find the hum frequencies.
Possibilities:
Mic is picking up EMI hum from the environment.
Mic is picking up hum from the camera PS or electronics.
Mic is recording hum from air handlers, refrigeration, dimmers that you cannot hear.

The lingering question for me is why are you putting a $150 mic on a $3500 camera? Azden is a B-line product.

Do some trouble shooting - fix the problem in the system rather than trying to fix it in post.
Have you tried different cables?
Does the camera record a hum with other mics?
Does the hum change when you change the position or direction of the mic?
Don't put your level on 'auto' unless you really can't monitor or adjust the levels.
Is the mic mounted on a boom and near the subject?
Are you monitoring off the camera with good, efficient, high quality headphones?
It could also be a ground issue in the mic that needs to be fixed. (I've had this problen with mics costing 10x as much - and had them fixed)

Another serious vote for iZotopes RX2. Conventional notch / band filters are very, very different to the type of filters RX uses to tackle this task.
You can really see this in Sound Forge with the spectrum analyser. Try as hard as I can I've never been able to cut say everything above 10KHz, best slope is around 18dB / octave even if I use a parametric Eg and set the Q to some large number. Do the same thing with RX2 and there is nothing , yadda, beyond 10KHz, slope is almost infinite, YIKES! RX uses "forensic" filters which are generally not used in normal audio because they can produce seriously bad sound. iZotopes have somehow figured out how to avoid this, to some extent, I know I've found RX2 has to be used with some caution but if you really need to filter out a specififc frequency or range of frequencies RX2 is only tool for the task. There is one other that I've never tried and that is Diamond Cut.


Bob.

tips:
Is your Azden SGM 1X shotgun a condenser or dynamic microphone?
Condensers use power either by phantom XLR connections or a battery, dynamic mics need no power supply.
If your mic is dynamic, beware of any transformers in the area, like power packs, dimmers switches, tv sets, anything that could emit magnetic fields - this is HUM. And your dynamic mic will pick this up if placed too close.
Condenser mics will not pick up magnetic hum, but the phantom supply must be totally clean.
lastly, - check your XLR cables!!! if you have XLR plugs at both ends, this means you are running a balanced system (pro system). So check you have the cables correctly wired - Pins 1 to 1, 2 to 2 and 3 to 3. Pin 1 is always the Screen (earth shield), go take a look, and test it with a meter.
if you have an XLR one end, but a mini jack or similar at the other - this means its an un-balanced system. This is usually a no-no. But you can wire these cables correctly if you know how to make a balanced to un-balanced cable!

If all fails, plug your mic into something else and see if it still hums - could be a bad mic itself, get what you pay for kinda thing.
Paul.

The microphone is an Electret Condenser Mic and it uses a AAA battery. Lots of mics are similar. The microphone is actually a decent one and instead of just condemning it based solely on it's relatively low cost, read the User Reviews at B&H and other places. How many of us own and rave about the now discontinued Audio Technica AT822? Mine cost me a little over $200. This mic is very similar in performance to the Rode Videomic that so many of us like. Read some reviews on it.

It has a low-cut switch. not a high-cut switch. That may add some noise if switched on, but I suspect that the noise came from the setup - either physical interface or settings on the camera. It may also have been picked up from lighting cables or even a ground loop. A three prong to two prong adapter can isolate that.

John

The OP hasn't ever replied, but I am not convinced that he has 60Hz hum - which is why I asked to hear a sample.

agreed Steve, would be good to hear 10 seconds or so.

"The microphone is an Electret Condenser Mic and it uses a AAA battery"...

Yep, and so i hope the OP already checked his batteries! . low batteries = low and usually distorted output, thus causing him to Up the gain! and therefor more noise.

Paul

Hi everyone... I've been on the road for a bit, and finally got back on the forum. I found a clip where the audio hum is obvious (scene without lots of actors talking). Take a listen:

http://www.vimeo.com/19960159

First my disclaimer, I'm not an audio expert, but I love to test & experiment. That's the way I learn.

Hum? I'm not sure that would be the way I would describe the background noise. I suspect the mic.

Next, I put your audio thru Sound Forge & Sony Noise Reduction (with some smoothing) - opened from with Vegas. Here's what I came up within: pinnochio.mp3. I'm sure others can do better, and I'd love to hear their technique.

....Jerry

Edit: Second and better(?) attempt: pinnochio2.mp3 (added clipped peak restoration and reduced smoothing)

There's hum in there, but there's noise all across the spectrum. Removing just the hum would not appreciably improve the situation.

Try the noise reduction software of your choice. Be careful, because it's easy to create artifacts with audio such as this!

Thats mainly white noise with a bit of 60hz hum thrown in for good measure.
This is a GAIN (excessive) / mic position problem probably because the mic is something like 50m away from the stage. Lots of echo too as a result.
Nothing much you can do here - its noisy for a reason, because its a bad mic placement - low signal from stage means you need to crank up the audio gain to such an extent that the pre-amp in your camera is actually amplifying not just the tiny signal, but all the the amp noise too. This is the Hiss you can hear. underneath that - 60Hz hum. Probably from lighting cables in the theater. Again caused by excessive audio gain.
conclusion: get that mic closer next time! Or get a feed from the PA board. Sorry i cant think of a quick fix here. Maybe someone else can. Dont think any EQing will help much. White noise (hiss) is right across the eq spectrum.
Good luck.

Paul

Jerry - thats not bad! Quite supprised anyone could save any of this.

Paul

Paul is right. The Noise Reduction plugin will work if you have it. I did this by capturing a noiseprint with the Sony Noise Reduction Plugin and choosing an 18dB reduction in Mode 0. Tried not to kill the audio making it sound like it was recorded in a tin can in the process.

CVM.mp3

John

"I did this by capturing a noiseprint with the Sony Noise Reduction Plugin and choosing an 18dB reduction in Mode 0. Tried not to kill the audio making it sound like it was recorded in a tin can in the process."Hmmm... I'm interested in techniques. I used mode 3 with 6db reduction and applied it 4 or 5 times with noiseprints chosen from "quiet" areas across the clip. Your result sounds quite good, however. And it's certainly less labor intensive. Wonder what's the best way to go?

...Jerry

Given that your "hum" was caused by a microphone attached to your camera by a relatively short cord, I suspected that you might not actually have a "hum" problem. I indicated this in the last sentence of my original reply where I said that you might instead have a noise that had a 60 Hz periodicity. This may seem like a subtle distinction, but the difference is actually very important, both for preventing the problem in the future, as well as solving the problem in the present.

Hum is the presence of a 60 (or 50) Hz sine wave and perhaps its harmonics (120, 180, 240 ... Hz). This results from directly picking up energy from the power lines, usually from long unshielded cables that are placed near power cords, or from poorly grounded equipment.

By contrast, many of the unwanted noise gremlins that creep into recorded sound are from devices that are connected to the power lines, but which then do something to that power and then re-emit energy with a totally different waveform than a sine wave. The most notorious and most common example is the light dimmer. While the circuits vary, the most common one uses a single SCR or Triac to instantaneously gate the power on in the middle of a power cycle. This creates a huge instantaneous spike in energy at the moment that the power turns on during each power cycle. Unlike the 60 Hz power line, the energy created by this process goes all the way into the radio spectrum and can radiate for long distances, and can easily get past simple shielding designed to prevent the low-frequency hum from entering your circuitry.

It is also a LOT tougher to get rid of.

Fortunately, the noise reduction plugins in both Sound Forge and iZotope can help remove some of this noise. However, the Sound Forge (Sony) NR is very long in the tooth and hasn't been improved for almost a decade. By contrast, the iZotope RX2 technology has been improved many times, most recently just a few months ago. It can not only do a very good job on this light dimmer impulse noise in your clip, but also reduce the broadband hiss. You simply take a short (1/4 second) sample from a completely quiet portion of the audio, and then use that to "teach" the software (click on the "learn" button). You then apply this envelope to your audio. The default settings will probably work, although you MUST resist the temptation to eliminate too much noise. When doing restoration or noise reduction work, less is more (meaning that you will do more harm than good if you attempt to get too aggressive with these tools).

You can also eliminate all those coughs and other distractions using the "spectral repair" features in iZotope RX2. You can also repair some of the damage done by the "hot" parts of your audio. You do have some fairly severe clipping in parts of your audio.

As for the future, you need to get a getter mic interface, and pay attention to shielding. Also, you need to use manual levels, and make sure that you get the mic as "hot" as possible, but without ever allowing overload. Doing this will raise the noise floor so you don't have so much hiss.

Finally, my recommendation from my initial post is worth repeating, especially now that I've heard your audio: get a feed from the soundboard, or at least place your own microphone down on the stage (with suitable mechanical shielding so it doesn't pick up footsteps). Using the audio from the back of an auditorium completely undermines the credibility you gain from having the nice HD video.

Here's a link (good for seven days) to your audio, restored using iZotope RX2. I did noise reduction, removed the clipping, and also used "spectral repair" to get rid of the pops and clicks that were picked up by your camera-mounted mic every time you changed the settings on your camera (don't mount the microphone on your camera, or at least use a mount that sonically isolates the mic).

Restored Audio

Record levels are too hot. Peaks are consistently clipped. This hits the limiter or AGC. Then, when the limiter begins to let go at the beginning of the selected area, the hum steadily crescendos over the next nine seconds.

"Even though on manual, your camera may have limiting that lets the noise floor rise in quiet spots. Make sure your audio peaks do not hit the limiter."

Net result: In addition to the clipping, you've left yourself with only a 30dB dynamic range. Drop your record input level by -6dB for starters, and see if all the peaks are captured. Even that much will reduce the perceived hum dramatically (pun intended). Then, if you add a little judicious compression in post, be careful to leave the noise floor under the radar (threshold).

See my previous post (above) for a complete description of the techniques used, and a sample of the result. I used iZotope instead of the Sony NR, but the techniques are the same as John's (craftech). My results are better, however. This has nothing to do with our relative skills (John knows what he is doing) but because the noise reduction in iZotope is so much better in every respect to what you get with Sony's noise reduction.

What I found was that trying to completely eliminate the noise killed the dynamic range and imparted an unnatural sound to the voice. I tried to strike a balance. I also tried to use what I thought he might already have in terms of plugins. I should have read his original post more thoroughly because he stated that he downloaded the trial of the Sony NR plugin and it did not work in 64-bit Vegas 10. So my attempt was pretty useless for his needs. Sorry about that CVM.

John

"I should have read his original post more thoroughly because he stated that he downloaded the trial of the Sony NR plugin and it did not work in 64-bit Vegas 10. So my attempt was pretty useless for his needs. Sorry about that CVM."Although iZotrope appears to do a much better job of noise reduction, I'm not convinced that Sound Forge/Sony Noise Reduction is still not an option for CVM. Even in 64bit Vegas, you can still right-click on the clip and "Open a Copy in Sound Forge", apply the NR as well as other audio effects and return to Vegas automatically replacing the sound clip as a take.

If you wait around for a sale, you can probably get the Sound Forge/NR package as cheap (or cheaper) than NR alone. Furthermore, at least to me, I like applying audio FXs in Sound Forge better than on the Vegas timeline (this might change since you can now apply realtime audio FXs within Vegas).

In other words, one can use NR from Vegas 64bit - and it works just fine - you just can't apply the NR FX to the clip on the timeline - it must be replaced as a take.

Just my opinion,
...Jerry