Post wizard needs pre advice on a mic

[janicesparty]

Hey! I'm no stranger to recording, both as a musician, and as an engineer. My entire career, I've been a wizard at just getting by with bad equiptment, and fixing it in post, and I do well for myself thusly.

I've run into a snag, though, on a project. I'm simply recording into a laptop with a condenser mic, and fixing the rest in post. The big problem is, the mic has an eigth inch jack that feeds directly into the ASIO of the laptop. There, while the mic is extremely good, the cable creates a very noticeable hum, that I've not been able to remove. So, my question basically is, "What is the best way to reduce the hum BEFORE recording?" If that question is a no go, I suppose the question is "What is the cheapest equiptment I can purchase to make this very good mic workable?"

Somebody suggested balluns, but I've never worked with them, and would need somewhat of a crash course. Any ideas are appreciated.

Roo

 

[8bus]

What kind of mic?
What software are you using?

 

[janicesparty]

A Tascam TM-ST1 is the microphone.

I am recording into Sonar 8, and using Sonar 8, Adobe Audition 3.0, and Soundforge to edit.

The Audition noise reduction is good, but it really changes the sound quality of the acoustic guitars, and vocals.

 

[dementedchord]

does the noise lessen when you run it on batteries??? instead of the wall wart...
some laptops have issuses with a floating grnd... best bet is get a real audio interface and leave the built in alone...

 

[antichef]

If the hum is really constant, you could try recording some of it alone on one track, and then copy/pasting enough of that to cover the full length of your other track (so that both the music track(s) and the hum track are the same length, more or less), then reverse the phase on the hum track and see if it cancels out the hum on the other track(s) when you sum them. (actually it might be worth experimenting on a small part of it before you got to that much trouble)

 

[mshilarious]

A balun is a transformer ("balun" = balanced-unbalanced). The theory is that would allow the cable to be balanced, and thus reject noise.

It isn't a theory that applies to your application at all. Both the microphone and the PC input are unbalanced, so you'd actually need two transformers (one at each end of the cable), and even that is not a guarantee, because the hum could be getting in through the microphone itself.

Your options for hum reduction with an unbalanced connection will always be limited. You should keep the cable as short as possible. In your case, I think it's hardwired into the mic, so you would have to chop it down . . . you should first try to eliminate potential sources of interference. Dimmer switches are notorious for this, but basically just turn off appliances, lights, and circuits in your house and see if the hum goes away.

If not, you will need to look at standard professional microphones with balanced XLR outputs, and a USB interface with balanced XLR inputs. That should kill your hum problem for good.

 

[janicesparty]

If the hum is really constant, you could try recording some of it alone on one track, and then copy/pasting enough of that to cover the full length of your other track (so that both the music track(s) and the hum track are the same length, more or less), then reverse the phase on the hum track and see if it cancels out the hum on the other track(s) when you sum them. (actually it might be worth experimenting on a small part of it before you got to that much trouble)

Wow, I didn't even think of phase reversal. What do you think would be the easiest way of doing this in sonar, not to experienced with the process.

Thanks for the suggestion.

 

[antichef]

Wow, I didn't even think of phase reversal. What do you think would be the easiest way of doing this in sonar, not to experienced with the process.

Thanks for the suggestion.

I don't know Sonar, but I found this in a web search:

"Cubase should have a phase reverse button right on the channel strip or track strip, however they refer to it. I know Sonar has it right on the strip in the main view for each track of audio. As well as in the mixer view."

Good thing it's easy, because it probably won't work (because the hum likely isn't constant/monolithic in character) - definitely worth a try.

 

[mshilarious]

For the polarity reversal trick to work well, you need to line up the two tracks so the hum is in phase. Otherwise, you could do anything from a cancellation to a reinforcement (making the hum louder!)

Record the hum track, then leave a silent lead at the start of your music track. Zoom in on the waveforms to 1ms resolution, and line up the peaks of the hum. Now reverse polarity and mix.

There will also be ambient and electrical noise (hiss) present, and unfortunately this technique will increase the ambient/electrical noise by 3dB. Your noise reduction plug should be able to offset that without too much damage.

There are hum reduction plugins that will do a better job than a basic noise reduction plug--they are EQs that will go after 60Hz hum, and the dozens of harmonics of that frequency.

 

[mshilarious]

Good thing it's easy, because it probably won't work (because the hum likely isn't constant/monolithic in character) - definitely worth a try.

Also very true. Here is a picture of a relatively complex hum, which illustrates the difficulty of phase alignment--polarity reversal and phase alignment worked OK for about 3 seconds of the 12 second samples I recorded:

 

[dementedchord]

ok... well if your gonna have any luck with the phase reversal trick it seems to me you would have too record the noise on a separate channel as you record the mic in real time... so the randomness of the noise can be accounted for... this would have to happen for each subsequent track... make sense???

 

[kidvybes]

"Tascam's TM-ST1 is a Stereo Microphone with stereo pattern-switching. The Recorder can select between 90-degrees and 120-degrees pickup to capture more ambience or to reduce background noise. The mid-side design captures a wide stereo field while maintaining a solid center image. The TM-ST1 uses a back-electrets condenser design for crisply detailed Audio with a long Battery life for portable recording. The Output cable terminates to a 3.5mm stereo jack, ideal for plugging into a DR1 recorder. Ideal for live recording, the TM-ST1 is a perfect accessory for Tascam recorders. The microphone can also be used with the US122L or US144 for portable recording into a laptop. The TM-ST1 excels at recording live music, school ensembles, worship ceremonies, songwriter demos and album recordings."

...considering you've been doing this recording thing for a while ("I'm no stranger to recording"), it might be time to step up to a low cost USB 2.0 audio interface as recommended in the mic's description above...sure beat's all the time spent trying to fix it in-the-box, don't ya think?...

 

[janicesparty]

There are hum reduction plugins that will do a better job than a basic noise reduction plug--they are EQs that will go after 60Hz hum, and the dozens of harmonics of that frequency.

Can I have some examples of such VSTs? If they're relatively inexpensive the may be well worth it.

 

[janicesparty]

One more thought... If I were to run an adapter from eighth inch to USB, could I run it through the USB port with less noise?