Buzzing in audio, especially noticeable after compression or raising volume

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Stax
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Buzzing in audio, especially noticeable after compression or raising volume

Post by Stax » Mon May 10, 2021 10:35 pm

Here's an audio sample
https://soundcloud.app.goo.gl/Knf81

I've been having this issue for a long time now and after replacing my old re20 with a new Shure SM7B I've been having the same issues, I've kind of given up and can't seem to diagnose the problem.

I do a lot of audio editing for others and decided to make stuff for myself. But I can't make clean, crisp tracks with this buzzing going on all the time.

Tech: Scarlett 2i2, shure SM7B XLR, gain 95%, microphone volume 75%, 48khz.

Upping the gain or volume only makes the buzzing more noticeable pre-edit

What is this and how do I fix it?

DVDdoug
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Re: Buzzing in audio, especially noticeable after compression or raising volume

Post by DVDdoug » Tue May 11, 2021 2:27 pm

I can't listen right now but since nobody has responded yet...

Hum or buzz could be a bad microphone cable. If moving the cable around changes the buzz the cable is probably bad (maybe a broken ground/shield connection). Or if you have a different cable, just try it.

Of course boosting the volume also boosts the noise. ;) Compression (and limiting) makes the quiet parts louder and/or the loud parts quieter so it makes the signal-to-noise ratio worse. Normally compression is used with make-up gain so it brings-up the noise floor.

Both of those mics are "famously" low-output dynamic mics. The output from SM7B is about 3dB lower than the RE20. That doesn't hurt with the acoustic room noise since the signal and acoustic noise are reduced together, but when you turn-up the gain you're boosting any electrical noise picked-up by the wiring or generated in the preamp. USB power from a computer is usually noisy and sometimes that noise can get-into the preamp of a USB-powered interface. (It's usually a high-pitch whine.)

A condenser mic will typically put-out at least 10dB more than a dynamic or ribbon mic.* Again, that helps with electrical noise but does nothing for acoustic noise. A Cloudlifter can sometimes help with a weak signal or a noisy preamp.



* Condensers have a built-in "head amp" which will generate some noise, but that noise is usually insignificant compared to the preamp noise.

kozikowski
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Re: Buzzing in audio, especially noticeable after compression or raising volume

Post by kozikowski » Tue May 11, 2021 3:38 pm

Here's an audio sample
We need to analyze that sound file and there doesn't seem to be any way to do that without starting an account.

That will fit nicely on the forum. Scroll down from a forum text window > Attachments > Add Files.

Koz

kozikowski
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Re: Buzzing in audio, especially noticeable after compression or raising volume

Post by kozikowski » Tue May 11, 2021 3:40 pm

This will probably be fine, but it's worth noting that posting an MP3 isn't optimal because MP3's job is create small files by throwing sounds away and cleverly hiding sound distortion. Use WAV when possible.

Koz

kozikowski
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Re: Buzzing in audio, especially noticeable after compression or raising volume

Post by kozikowski » Tue May 11, 2021 3:57 pm

It does sound exactly like wall power leaking into the sound.

See: DVDdoug. Try the second 2i2 connection and see if it changes.

Also: Do you have any dimming lights in your studio? Run them all the way up — or off and see the the noise changes.

If on a laptop, see if it changes if you run both plugged into the wall (shore power) or on batteries. There's a note here that "My laptop hasn't worked on batteries in months" is a bad answer.

Are your studio lights compact fluorescent? They're famous for making buzzy noises even worked normally. Work in the dark by candle once and see if the noise changes.

What kind of monitor do you have? Screens can make noises. Tube monitors were famous for this, but you can get flat screens to do it, too.

https://www.kozco.com/tech/audacity/cli ... Edited.mp3

Write down if you can get the noise to change, either up or down.

Koz

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Re: Buzzing in audio, especially noticeable after compression or raising volume

Post by kozikowski » Tue May 11, 2021 4:21 pm

That will fit nicely on the forum.
Many noise problems have signatures and in some cases we have pre-baked filters to suppress the worst of it. It's still best to keep your system from making the noises in the first place.

RE-20, SM7b. I'll take whichever of those you don't want, 'K? I'll pre-pay shipping.

Koz

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