Problem recording voice-over: weak levels

PossibilityX wrote on 3/22/2005, 4:52 PM

I finally figured out how to hook a mic to my computer to record VOs, but I'm a bit stumped RE: how to bump the levels.

I go from a shotgun mic into a SignVideo XLR-Pro and from there into the computer. (Not ideal, I know, but that's what I have to work with.) Levels on the XLR-Pro are maxed. I record to an audio track in V5. Everything works well as far as it goes, but the audio in the waveform is almost invisible and I have to bump it by normalizing each clip, a pretty tedious process. (It goes up by 19 - 23 dB, just to show you how anemic the waveform is.)

The question is, how do I adjust the record level so I get a nice signal / waveform?

Thanks in advance for any help.

---John

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FrigidNDEditing wrote on 3/23/2005, 5:54 PM

Well, I'm hoping that VERY SOON my short term pocketbook will be less valuable than my long term time ;-)

No- I hear ya on that, That's one of the main reasons people don't print their pictures at home much from their digital camera - just copy the pics onto a CD, print one from each of the cd pick them in a little while. No more print....print.....print..... print..... etc...

Dave

PossibilityX wrote on 3/23/2005, 7:02 PM

Chienworks, I did go to the sound card control panel and raised the record level. It was at about 50%. I maxed it to 100% which made a noticeable difference in the waveform, but it's still pretty flat compared to the audio I get from DV tape.

On normalization, it only had to jump 9 - 11 dB. An improvement.

Regarding budget as per FrigidNDEditing's question, right now it's zero. This little experiment is just an attempt to jump in and see what I can do so that, when the time comes, I'll be somewhat familiar with 1) what I need to do and 2) the (ever more obvious) limitations of my gear. There's no reason right now to buy a new mic or soundcard.

But when the time comes, I'm inclined to save up and get something fairly decent, as opposed to getting something sooner, but cheaper and less robust. DSE makes a good point about long-term ease of use and quality being more valuable than saving a few bucks, but having a crappy recording.

Thanks again for all the input and energy. You're all my professors. These last couple of years with Vegas have really amplified me, and I'm still very much a newbie. If I'm having this much fun after just scratching the surface, how much fun will I have after I've memorized all the keyboard shortcuts and purchased a Shuttle Pro? <g>

Chienworks wrote on 3/23/2005, 7:20 PM

LOL! I still haven't purchased a shuttle pro, nor have i even begun to memorize all the keyboard shortcuts. Yet, somehow, i do manage to have tons of fun with this software!

Blues_Jam wrote on 3/23/2005, 10:16 PM

and then there is the under $20 solution that works surprisingly well. It is an impedance matching transformer that will step up the signal from your relatively low impedance mic to your relatively high impedance sound card's mic pre-amp input. Radio Shack has one for $15;

http://www.radioshack.com/product.asp?catalog%5Fname=CTLG&product%5Fid=274-016

Shure has one for about $5 more. Plug your mic's XLR cable into the adapter which terminates at the other end with a 1/4" phone plug. You will then need a 1/4" mono to 1/8" mono adapter (another few dollars at Radio Shack) to plug into your sound cards mic input.

It looks a bit cumbersome because of its length but can work very well. I have personally used one to connect an SM-58 Beta to a laptop with a very noisy on-board sound card with excellent results.

Be sure to turn down the mic input volume in your sound card's control panel and uncheck any db boost box to start and raise as needed. You will likely find your volume setting to be quite lower which is a good thing because the higher that setting the more you are amplifying the internal noise of the card's mic pre-amp.

Blues

PossibilityX wrote on 3/27/2005, 8:05 AM

Thanks to all who offered tips and suggestions---much appreciated.

Here's something I should have checked first, though. Out of curiosity, I replaced the battery in the mic. Evidently THAT was much of the problem, because this resulted in a noticeably hotter signal; I could actually see the waveform build as I was recording. I didn't really need to normalize afterward, but I did just to check the difference.

This time there was only a gain of about 8dB. Much better than the 19 - 23 needed at first!

Just goes to show you: Keep fresh batteries on hand, and replace them often.

Bob Greaves wrote on 3/27/2005, 9:05 AM

On of the most common problems I have noticed people who are not audio engineers will make is to assume that all microphone signals are mic level signals all the way through the audio chain.

Coming out of a microphone, the signal has a strength and an impedance that must be matched by whatever the microphone is DIRECTLY plugged into.

After that, unless the device the microphone is DIRECTLY plugged into is a passive device, the signal is no longer a microphone level signal.

For example, when you plug a microphone into a preamp, the preamp output is line level

The second most common mistake is to assume that all line levels are the same. Line level signals have a tendancy to come in balanced +4Db, prosumer 0 db and consumer -10Db. These can be mixed and matched but only when you understand what each input and output represents.

The more professional you get at it, the more you will prefer to work with balanced signals that are converted to line level and expect +4 Db. If you use the Camera as a sound recording device, you should do well so long as the AGC is off. Many DV cameras permit a line level input.

Bottom line, just as video comes in various pixel sizes and various resolution standards, so too do audio signals. Feed the signals properly and they should stay very healthy.