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My USB is mic started producing white noise

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My USB is mic started producing white noise

Postby Saza » Mon May 17, 2021 1:04 am

Hi,
I used to record voice-overs with my Shure PG27 USB mic on an iMac with no problems whatsoever. But, since I switched to a Windows PC, many problems started to occur seemingly out of nowhere. Sometimes the input volume is too low or too high, even when I didn´t touch the main input volume in settings.
Now the most annoying issue I´m experiencing is that the mic generates a very noticeable white noise that is sometimes louder than others. Changing USB ports doesn´t always work, neither changing the cable. It produces the noise even when the mic´s gain is set to 0.
These issues that I never had with my old Mac are intermittent and are driving me crazy, especially when I have my clients supervising the recordings right there with me.

My set-up:
Windows 10 (fully updated)
Shure PG27 USB mic set to -20dB
RTX 2080 video card (fully updated)
Recording software: Adobe Audition (I tried with Audacity with the same results)

Here´s a recording of the noise: https://voca.ro/1o1KzKPNTIvl

Any advice will be much appreciated!
Saza
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Re: My USB is mic started producing white noise

Postby Wonks » Mon May 17, 2021 7:57 am

Hi and welcome.

When you say the mic is set to -20dB. that sounds like you've got the pad switch engaged.

This is for use when recording very loud sounds, and reduces the signal going to the pre-amp by 20dB. For spoken vocals, you simply don't need it, and the preamp will have to provide an extra 20dB of gain to get the signal back to the required level. More gain equates to more noise. so the first thing to do is set that pad switch to 0dB.

Intermittent gain levels sounds rather like the gain control pot is wearing out or making bad contact. This could cause the gain level to go up and down and as the gain increases, any noise produced will also increase.

It may well be that some contact cleaner spray would sort out the potentiometer (if it is going faulty), but I wouldn't want to spray into a capacitor mic like that without dismantling it first and screening off all the other components.

TBH, this mic is not one that I'd use to record voice-overs for what i assume are paying clients. USB mics are fine for basic podcasts, but with this one you are limited to 16-bit recording and these days you should be looking at 24-bit recording for anything that aspires to be remotely professional.

With 16-bits, you need to record close to the 0dBFS level to keep the recording above the background noise floor, but you risk louder noises exceeding 0dBFS and causing digital distortion. Too low a recording level, and the noise floor will become audible (probably made worse by having the -20dB pad in).

With 24-bit recordings, you can afford to record with plenty of headroom and still remain well above the noise floor of the system. So, I'd suggest getting a separate audio interface and a better quality microphone, not an all-in-one USB mic. It is the professional way to go. Whilst there are 24-bit USB mics availble, they are always a compromise, and if you are charging for this, rather than just doing it for fun for friends, then I'd definitely go for a better recording system.

You've got a very powerful graphics card, suggesting a games or video rendering PC, and I'm just wondering if your 'white noise' may simply be the mic picking up background fan noise from the PC, especially if the gain has jumped up due to a faulty pot. It doesn't sound like ground loop noise to me, or humidity affecting the sound.

Placing the PC in a position to minimise noise from it being picked up by the mic, maybe using a screen, will help to reduce the overall system noise floor. The ear/brain is good at blanking out background noise, but a mic can't do that, so what may be inaudible to you becomes very audible when put on a recording.

I've obviously had to make some assumptions here, but any more information about your recording set-up would be helpful. What sort of room, have you any acoustic treatment in it, what are you using for monitoring etc?
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Re: My USB is mic started producing white noise

Postby Mike Stranks » Mon May 17, 2021 9:38 am

Greetings and welcome! :thumbup:

Wonks has touched on a key point about spoken word work of any kind. This is what I do for 90% of the time and I wouldn't choose a USB mic. You need something that's going to give you as good a signal to noise ratio as possible.

From my own experience and in relative order of importance I'd say you need:

* A recording space in a quiet location with no traffic, rail, aircraft etc noise.
* A good recording space that has been treated appropriately for recording voice.
* A decent capacitor mic ideally with a 1" capsule and with low self-noise. I'd be looking at something with self-noise of -16db (A weighted) or ideally less. That's my ideal; there are some good mics out there that don't meet that criterion though.
* An environment where you don't introduce any extraneous noise - eg computer fans. I don't record to computer at all, but use a decent solid state recorder and then transfer the files to computer for editing and mixing.
* If you must record direct to computer then get a decent audio interface with mic preamps that will give you 60dB or more of clean gain.

... and from what you've written it looks like your mic may have developed some sort of fault.

Hope that's of some use. :)
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Re: My USB is mic started producing white noise

Postby Saza » Tue May 18, 2021 4:12 pm

Thank you Wonks and Mike! Those are many golden nuggets of information.
I really appreciate you took the time to post such extensive responses.

I´ll be looking for a 24-bit XLR mic with a good audio interface that doesn´t require breaking my piggy bank since I don´t do voice-overs as my primary source of income (any suggestions are welcome). Wonks is right, I have a rendering machine for animation and I occasionally make some voice-overs for them.

About the noise problem, I tried disconnecting all the fans and the noise kept on getting in the recordings, I assume it was some type of interference with the cable or the mic itself.
What I finally did was plug the mic through a powered USB hub and that solved the noise problem at least for now. I moved my setup so much that is hard to know if that was the solution, but I´m posting it here in case somebody else finds it useful.

Again, thank you so much for the replies!!!
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Re: My USB is mic started producing white noise

Postby Wonks » Tue May 18, 2021 5:28 pm

Glad things are better than they were.

It sounds like your USB port couldn't quite provide enough power for the mic, but the powered hub has solved that issue. It had enough power to work, but not at an optimum level for noise.

A decent mic and interface shouldn't cost too much money at all, and will be a big step towards better voice-over recordings. Something like an AT2020 is probably the lowest cost mic to consider, but you want a mic that suits your voice, so if you can in the current climate, it is worth auditioning a number of mics to find the best match for you. Always better to take a friend along with you and get their opinion, as they are more used to your voice as it sounds to others, rather than the modified sound you hear through the air and direct bone conduction.

But you'll also need to give some thought as to how you can reduce the background noise reaching the mic, and improving the acoustic environment within your recording space.

The easiest and cheapest place to begin is by hanging up thick duvets, especially between you and the computer and in a rough circle around the back of you. You could look at putting up proper acoustic treatment panels, but that may not be appropriate if it's a multi-purpose room you're using.
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Re: My USB is mic started producing white noise

Postby Mechelsohd » Sun May 23, 2021 10:52 pm

clear the contact or change the microphone
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