Based on Feedback - Got 2 Mics to Remove Background Noise

Discussion in 'General Discussion' started by CatMalone, Aug 7, 2019.

  1. CatMalone

    CatMalone Active Member

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    Hello :)

    Based on the feedback I got from respected members of this forum I ordered dynamic mic(s) to eliminate the background noise because all the other options (whichever was possible at my end) I already tried and getting mic was the only fix.

    I've a home studio setup where I create educational video course and currently using MXL 770 with Scarlett solo 2nd gen.

    FYI: So far I got SM57
    and SM58 is in transit and I will try both of them whichever works best to eliminate the background noise I'll keep that and return the other one.

    I did 1 Minute demo recording at 3:30am:

    Note: Fan and Ac was off and only, some noise was coming from outside...

    First test:
    Scarlett solo 2nd gen: Gain 75%
    MXL 770 - It picked up a lot of noise

    Second test:
    Scarlett solo 2nd gen: Gain 79%
    SM57 - I recorded noise for first 30 seconds then spoken something for 1 minute.

    Recording: https://www.dropbox.com/s/ujx3dvhb3c21j2k/79%_gain_SM57.mp3?dl=0

    1. Request - I request you please listen to the recording and check whether the background noise is completely removed or not as I don't have monitor headset.

    2. I listen to the recording, even though gain was 79% but still volume is low. I guess If I increase more gain than mic will pick up noise and audio interface may also generate some noise isn't? So whats the solution for it? Should I use Audition/Audacity to increase the gain (using Compressor or Amplify effect) but I guess that will also increases underlying background noise (if it is in the recording)?

    Please forgive me, I'm afraid, after listening to SM57 it sounds like it-isn't have rich and warm sound like MXL 770. It sounds somewhat flat but I'm grateful I got this.
     
  2. bouldersound

    bouldersound Real guitars are for old people. Well-Known Member

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    To really make a difference in minimizing the environmental noise you need to get very close to the SM57. On the plus side, the grille is really close to the diaphragm, so allows getting close. On the minus side there's not much pop protection and you'll also get more proximity effect (bass boost). If you've got a pop screen, put it right up close to the grille on the 57. Once the recording is done, apply some eq to compensate for the proximity effect. A wide shelf cut that rolls on between 500Hz and 800Hz should do it.
     
  3. CatMalone

    CatMalone Active Member

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    (This was my first question which asked above)
    1. May I ask you have you listen to the recording? Have you found background noise?



    (This was my second question which asked above)
    2. I listen to the recording, even though gain was 79% but still volume is low. I guess If I increase more gain than mic will pick up noise and audio interface may also generate some noise isn't? So whats the solution for it? Should I use Audition/Audacity to increase the gain (using Compressor or Amplify effect) but I guess that will also increases underlying background noise (if it is in the recording)?

    I'm afraid I asked above 2 questions which you missed to address. The reply which you mentioned I appreciate that but it'd be great if you answer my specific questions :)

    2. I was already very close around 1" away during above attached recording.

    I have only one pop screen attached to MXL770 so I used handkerchief, folded it multiple times and attached on the grill, it protected from plosives...

    Is there any tutorial on Youtube or any article on this?
     
  4. bouldersound

    bouldersound Real guitars are for old people. Well-Known Member

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    One inch is pretty close. You may be able to get closer. A handkerchief will reduce the high frequency response of the mic so a proper pop screen might be an improvement.

    Here's the eq I applied to your recording:

    sm57 test eq.jpg

    Along with that eq I added some compression and a mastering limiter to raise the level. There is some noticeable noise. Is that your computer fan? I can also hear a bit of your room reverberation.

     

    Attached Files:

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  5. paulears

    paulears Well-Known Member

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    Is the link for recording one missing? Can't see it - have the sm57 one.
     
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  6. paulears

    paulears Well-Known Member

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    I have a suspicion that what we are listening to is a bit unusual. I listened very carefully to the recording - and the record level is still too low, but the audio quality from the 57 is what I expected - it sounds like a decent dynamic.

    The noise is very odd - it has low frequency components, which makes people think it's air handling noise, or computer fans or other physical things. We need to eliminate this.

    What you need to do is a recording - at the same gain setting and then half way through, pull the mic plug out - we will then hear a click/pop and then ANY noise is being generated totally in your interface, and this will be exactly the same with any microphone. The preamp noise. If the noise vanishes, however, then it IS noise in the room, but this should be evident when you are sitting in the room. We did this recording a while back

    I'm not sold whatsoever on the often accepted opinion that dynamic mics are better at rejecting background sound. My 0wn experience is simply that some mics do it better than others, but the reason is not their capsule type, as in dynamic or condenser, but their individual polar pattern. All mics have lobes, and they're in the specs. If a noise source sits in one of these, then it's heard. If it's in the null, it is quieter. Cardioids have vents behind the capsule - they need these to operate in pressure differential mode - these vents allow sound in from other than the front. I have one of the AKG dual diaphragm cardioids, where the bass element has a vent in the handle, and these have quite pronounced rear pickup if you just go one-two-one-two and rotate it. The Beyer M201 hyper has really poor rear rejection, which means that sound from the back is quite audible. It's narrow of course so side rejection is good. The sM57 and 58 have a pattern that make rear pickup lower but it hears more to the sides either side. In practice, with a PA, a wedge speaker on the floor behind a 58 can go pretty loud, but if you swap to a condenser super, like an SM87a, the rear wedge speaker feeds back easily, but if you have two one either side of centre it works fine as that's where that mic is least sensitive.

    I have condensers that pick up background noise from certain directions and others that don't. I really cannot say any of my mics have differences caused by their capsule type. Condensers have more output in general, and often get used a little further away - I wonder if this is why people say their noise pickup is worse? I believe it's simply signal to noise - how much voice to how much room noise controlled by distance and polar pattern. I've always believed this.

    if you listen to that clip - and it's not done with a wonderful interface - just a normal one, you can see and hear differences. People can judge for themselves how room noise intrudes. The fan is pretty loud in that computer, and can be a problem. The test only looked at the rear pickup. Maybe it helps?

    Do the test with pulling the plug out during recording -- this will prove where the noise is being generated. What is clear is that it it not pink or white noise - it has lots of energy down the bottom, which is very strange.

    The Coles shows the noise from the Tascam preamps when normalised to get the level up - it's very low output, far worse than the SM7B which is often cited as a problem because of the extra gain you need - the Tascam hasn't got brilliant performance but it's fine. Clearly the AKG condenser is indeed the one that picks up the noise in the room, but I honesty think it's because the capsule is exposed. All the others have the body of the mic as a barrier - that's how I see it. others will disagree, but the AKG does make room sound worse, despite being set to cardioid. Odd!
     
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  7. bouldersound

    bouldersound Real guitars are for old people. Well-Known Member

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    I agree. I think it has a lot to do with polar pattern, distance to the mic and mic frequency response.
     
  8. CatMalone

    CatMalone Active Member

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    I intentionally didn't mention the link because it was terrible recording. Right now I tried to add the link but there is not Edit option to edit the thread so here is the first Recording link (as you requested):

    Recording: https://www.dropbox.com/s/wpo26k5dq1xyjee/75%_gain_MXL-770.mp3?dl=0
     
  9. CatMalone

    CatMalone Active Member

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    Alright, I'll start using the pop filter every-time I'd use the mic :)


    Thanks, I listened to the file which you attached and
    Yeah, I also tried the compression (and also at other time I tried the amplify effect) at my end and it increases volume of background noise.

    No, the computer fan is quite (I assure you). This kind of noise is coming from outside. I investigated earlier and found that someone living at the ground floor, is running very old era fan which makes noise when it runs and they run it almost all the time that's why I picked up night time to work because at that time I just have to deal with this noise and with not other noise sources which are available in a day time (ex: someone talking at the street or street hawker going by etc...). Night time is pretty quite except that outside noise.

    I bought SM57 (and SM58 is on it's way) is the result of this thread https://recording.org/threads/is-it-possible-to-make-recording-sound-better-via-software.64656/ Members recommended me to get this dynamic mic so that mic doesn't pickup that noise and I analyzed MXL770 picks up around -42db to -34db (noise level) whereas this SM57 picks up upto -52db (noise level).

    With SM57 I was happy to record when I found -52db (noise level) but another issue came up: the volume level was low while recording with SM57 even though I set the gain to 79% and now the issue if I increased the volume in post via compression or with amplify effect then it also increases the noise level (which you also experienced). What do you say about it, how to fix this?
     
  10. CatMalone

    CatMalone Active Member

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    I sincerely appreciate what you mentioned and also your diligence to figure out the issue, it's really outstanding.


    I again did the recording, exactly the way you suggested. Here is the audio file:
    Fan and and Ac is also switched off and computer fan is already quite.

    Audio: https://www.dropbox.com/s/6o7ojarg3wso4yp/79%__gain_SM57_MicCable_Unplug.mp3?dl=0

    Audacity Video: Here is the screencast (video) in case if you want to see how it was being recorded in audacity and you can see the recording level was around -54db even before speaking (which is noise level):

    https://www.dropbox.com/s/05zlyck7tgvks0b/79_gain_SM57_MicCable_Unplug.mp4?dl=0



     
  11. bouldersound

    bouldersound Real guitars are for old people. Well-Known Member

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    At least we know it's actual sound from your environment. That's what I was trying to determine.

    What ultimately matters is the ratio between the signal you want and the noise that you don't want. The bigger the difference between those two things the better. As others have said (over on the other forum), a dynamic mic is going to have a lower output all else being equal. But all else isn't equal because you can get closer to it than to most condenser mics. That's your best bet for minimizing the effects of the noise.

    Don't be afraid to increase the gain as needed for recording with the SM57.
     
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  12. paulears

    paulears Well-Known Member

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    We're getting somewhere I think. we've established that the noise is 100% 'real' noise in the room, so now we are left with a few choices as to how to proceed. I think that we now need to establish how the noise is getting to the mic. We've looked at the response from the rear of the microphone as the cause, but have we yet located the source? If there is a piece of equipment generating it, we can determine it by moving the mic around in the room, listening on headphones until we hone in on the source. Then we have simple choices. The inverse square law works for us by maximising distance to the noise source and minimising it to the voice. We also have the option of barriers - inserting something physical in the way that either absorbs it on it's path to the mic, or diverts it, increasing the distance.

    On the other hand, the noise could be arriving at the mic by getting into the room from a number of sources, and probably windows will be the obvious easy route.

    Where I live, in the still of the night the air-conditioning fans from an industrial/retail site half a mile away are clearly audible - a very low frequency persistent noise, similar to yours. Is it possible that the natural noise floor of your area, with the heat and need for things like air conditioning just mean your local silence is anything but silence - made up of large numbers of fans?

    Have you tried using the cardioid pattern of the mic to find, rather than reduce the noise? turn the gain up, put the headphones on and rotate on the spot with the mic in your hand and try to localise the noise. I'm thinking doors and windows really. As the noise is low in frequency, the usual temporary fixes like hanging a duvet on a mic stand or two might be less effective than usual, but ANYTHING between the noise and the mic will be positive - we're unsure just how positive.

    My recommendation is:
    Find the source if the noise for certain.
    Place the microphone so that direction is in the least sensitive part of the polar diagram.
    Evaluate how well this works
    If you find little or no specific direction differences, then the unwanted sound is getting in by multiple pathways and you are left with one real solution. Mass. You need to improve the physical construction of the space. Weight, cost, and practicalities emerge here.

    One thing - all your recordings do sound like you are speaking quietly, and not that close to the mics. Perhaps you need to simply increase your volume, or get even closer, which will take the noise down? You will start to get pop sounds and the extreme bass tip up as the proximity effect increases - but EQ can help here and various types of pop filters can usually sort it out - your recordings seemed quite pop free, suggesting distance reductions are still possible. Your quiet spoken voice is also not helping - do you have a radio news reader voice - the sort of volume you would use to talk to say, a group of ten people across the table from you?

    Perhaps a photo of your setup might help us? A short video clip from a phone, pointed at you as you are speaking into the mic. In the video I put up - the noisy fans in our computers virtually vanished when the lips touched the basket/foam on those mics - an inch and a half coupled with a quiet voice could be too much?
     
  13. bouldersound

    bouldersound Real guitars are for old people. Well-Known Member

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    The SM58 may work for you without an additional pop filter. Try it with your lips touching the grille.
     
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  14. pcrecord

    pcrecord Quality recording seeker ! Distinguished Member

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    Just in case, somebody finds this thread via google search.
    Mics aren't tools to eliminate noises. They capture sound (whatever hits the fan.. sorry the capsule) ;)
    So you are trying to record less noises by choosing the right mic with the best rejection due to it's capture properties.. (polar patern or other...) That's perfect !!
    Of course, the best way to not record noises is to remove the source from the equation but we sometime can't.

    I'm sorry I stuck on the term eliminate. Record less would have been more precise..
    For I being annoyed by this only proves I'm getting old !! lol
    I just pray to not be the next lady on RO with brain damage.. :ROFLMAO:
     
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