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philsvoice · Posted: Tue May 04, 2010 6:33 pm Post subject: Very low levels using Audacity

EVeryone:

I have a Shure SM27 mic connected to an M-AUdio Firewire SOlo interface and an iMac running Audacity. I have been having very low levels for the last two days and can't figure out why. Just for the hell of it, I turned up the gain knob on my interface all the way to the right. Strangely, everything is clipping at around -8 dB. What could be causing this problem? Here is a link to the sound file. I start speaking at around 20 seconds or so. I recorded the background noise in the beginning for reference.

http://voice123.com/mp3/demos/philiphwang%20-%20May%204.mp3

Mike Sommer · Posted: Tue May 04, 2010 9:40 pm Post subject:

Well, the distortion we are hearing is Analog, so that means your clipping the M-Audio's preamp. So turn it back down so that's it's not clipping.

On your Mac go to:
System Preferences > Sound > Input.
Make sure the M-Audio device is selected, then try increasing the "Input Volume."

Let's see if that helps.
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philsvoice · Posted: Thu May 06, 2010 5:57 pm Post subject: Still having a level problem

I went into System Preferences and increased the Level to the maximum level. I'm still having the level problems. How can I isolate the cause of the problem: mic? cable? audio interface? software? This problem all of a sudden appeared for no reason.

http://voice123.com/mp3/demos/philiphwang%20-%20May%204.mp3

Frank F · Posted: Thu May 06, 2010 6:20 pm Post subject:

This to me sounds a bit like a cable impedence issue. I could be wrong, but replace or re-seat your cables - including the USB cable 0 to begin with.

It is NOT the software.

Frank F
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Mike Sommer · Posted: Thu May 06, 2010 6:58 pm Post subject:

Let's try something real simple here. On the mic are two switches, one is the roll off switch, and the other is a 15dB pad.

Make sure the "Pad" switch is set to "0" and the roll off is set to the flat position "-" (this indicates no roll off).

Lets see if that helps.
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Acoustics are counter-intuitive. If one thing is certain about acoustics, it is that if anything seems obvious it is probably wrong.

georgethetech · Posted: Sat May 08, 2010 12:26 am Post subject:

Audacity is the only audio recording a Hobo Tounge

I know that has a mic input level slider, which can really get in the way. Make sure it is turned up.
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philsvoice · Posted: Sat May 08, 2010 6:23 am Post subject: Mic Cable

Everyone: Thanks for all the input. Regarding my mic cable, I have a high quality $40 cable that I got from BSW warehouse. The cable runs from my interface (which is on my desk) to the mic (which is in my closet). In between, I usually leave it under a rectangular pad of carpet so I avoid tripping over it. Is this bad for the cable? Should I unplug the cable from the mic and the interface when its not being used?

Mike Sommer · Posted: Sat May 08, 2010 8:59 am Post subject:

Did any of the other suggestions work?

Keeping everything plugged in and cable under the carpet is fine, just put a sock or something over the mic to keep it and the capsule from getting dusty.
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Acoustics are counter-intuitive. If one thing is certain about acoustics, it is that if anything seems obvious it is probably wrong.

philsvoice · Posted: Sat May 08, 2010 10:25 am Post subject: Problems

Mike: The bass rolloff to my mic was not on, and I didn't have the -15 dB floor on either. This is just a perplexing problem. If my mic has indeed gotten too dusty, is there anyway to clean the dust out?

I'll experiment with a different mic cable and see if that helps. It may simply be a dud cable.

Mike Sommer · Posted: Sat May 08, 2010 11:53 am Post subject:

Cleaning a capsule is a delicate matter and should be left to a professional. And to clean it you'll need to take it apart. If you do that: With a very Very light breath (no spittle), you should be able to blow off the big stuff. Otherwise use a very very soft art paint brush or the lightest-of-touch with a Q-tip.

Post a screenshot of your audio waveform in Audacity so we can see what's going on. Here's how to do that: http://graphicssoft.about.com/od/screencapturemac/ht/macscreenshot.htm

Simply try unplugging and plugging the cables.

Are you powering your M-Audio unit via the USB cable? If so, try using the AC wall adaptor (wallwort). It could be a power supply issue.

Check your Audacity settings as George mentioned. Just below the Stop, Start and Record buttons are the Playback and Record level sliders. Make sure they are up full.

After that run down to the Shiny Stuff store, and get a new cable and try that.

If that does not help get it could be the mic or the M-Audio
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Acoustics are counter-intuitive. If one thing is certain about acoustics, it is that if anything seems obvious it is probably wrong.

Frank F · Posted: Sat May 08, 2010 1:06 pm Post subject:

Mike is right on target about the Power Supply being a good possibility to the issue.

Not enough power is always a possibility with computer which may or may not have a powered USB port. Switching out cables is the next real step, including the USB cable.

Where you mentioned a "clipping" (i.e.: compressed look) type look associated with the smaller waveform - the ideas mentioned are likely culprits for the situation.

However, all the above solutions may not resolve the issue. Do you have another sound card? If so, plug it in and fire it up. See if your levels are better and if there is any clipping associated with the audio. If the waveform looks better then it is time to take a good look at the M-Audio box as being the problem in the chain.

If you do not have another sound card, try changing the USB port, which is currently being used by the box. to another port - AND changing out the USB cable.

Sound cards fail for no reason. But it is always wise to check out other, easier, and less expensive, ideas to fix a glitch.

Good luck. I DO understand how frustrating these things can be when trying to get some work done.

Frank F
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philsvoice · Posted: Mon May 10, 2010 6:39 pm Post subject: THanks guys

Actually I'm using a 6-pin Firewire connection from the interface to the six-pin Firewire port on my iMac. According to the M-Audio user's guide, I don't need the power adaptor if I'm going from 6-pin to 6-pin.

However, I'll try another Firewire cable and see if that helps, and I'll try another mic cable.

Thanks everyone.

Lance Blair · M&M Joined: 03 Jun 2007 Posts: 2281 Location: Atlanta

Phil, what do you mean by "low levels"? What were they before? You're getting plenty of gain with the input cranked, so much so that it's clipping.

Give us some numbers, or show us a screenshot of your waveforms. Some facts would help. It's like telling an auto mechanic "my car doesn't get good gas mileage, and it did before". What are the settings on the Firewire Solo mixer interface?

Can we hear a recording without the gain cranked? How does it sound when you're peaking at -20dbFS?
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Mike Sommer · Posted: Tue May 11, 2010 9:30 am Post subject:

The power problem is not because of the cable, but rather your power supply could be failing in the computer, or a bad connection.

The one thing you don't realize is that firewire and USB devices power are about 12vDC. You are powering a preamp, the interface the mic via the computer connection. Taking that into consideration and the fact that you're creating Phantom power, a 48v DC power source from a 12v power supply by tripling it. This gets you to about 36 volts- good enough to power a mic. But if your suffering form a bad computer power supply. you voltage could be considerably lower. Try the wallwort power supply.

As Lance stated give us screen shots of the waveform. Make sure the preamp is not clipping, when you record the new sample.

Also if you have saved a file of a recordings where the levels are at your liking. Giving us screenshots of that too, this would be very helpful. And if you could post a sample of that also, that would be great.
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The Blog:
http://voiceoveraudio.blogspot.com/

Acoustics are counter-intuitive. If one thing is certain about acoustics, it is that if anything seems obvious it is probably wrong.