Trying to get microphone audio levels right

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sirsquid
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Trying to get microphone audio levels right

Postby sirsquid » Sat Apr 27, 2019 9:09 pm

Hi all, new here.

I've started doing a podcast recently, I doubt anyone will know who I am (I will be surprised if someone figures it out :P). All done on Linux of course, Ubuntu.

I'm using the Zoom U-22 with the MXL BCD-1 Dynamic Microphone and they're both quite nice and plug and play. The issue I am having, is that even with Output at max and Gain at around 8.5/10 on the Zoom U-22 the volume picked up by Ubuntu/Audacity/Pulse (all the same levels) is really low.

With the microphone pretty close to my face, it's only picking up -30 at a little louder than normal speech. Even with Gain cranked up to 10, it's still only hitting about -18 but then it also picks up a little background noise.

Are these types of levels normal? I've seen others say they record at a really low volume and then amplify in Audacity but it makes editing a pain for me having to either amplify it or turn my speakers up really high to even check it over?

Musicteacher
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Re: Trying to get microphone audio levels right

Postby Musicteacher » Sun Apr 28, 2019 7:02 am

Hi,
there are combinations of microphones and mic-preamps that do not work well (low output mic combined with low amplification preamp). I did not find anything in the net if your mic is very low output or your card very low gain, but it might be.

You can
- try another mic
- try another card (you might now people where you can borrow those)

The zoom has an input for a separate power supply, you should try that, too. Maybe your usb gives not enough power.

On the software side, you might want to do the following:
Use the following chain: Noise gate - compressor - limiter

You can either plug those together with jack and use the output of the limiter as record-source for audacity or discard audacity and use a real DAW that allows for real-time plugins.

Of course, if mic and preamp do not work together well, this cannot be completely undone with software, but it can be improved quite a lot.

Unfortunately, there is quite a lot for you to learn , using jack and a DAW is quite complicated for beginners!

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wjl
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Re: Trying to get microphone audio levels right

Postby wjl » Sun Apr 28, 2019 8:52 am

Hey Sirsquid,

as Musicteacher already pointed out, it's probably the combination of (dynamic) microphone and audio interface here, try to verify that with other equipment if you can (borrow another mic and interface from friends, or try it in a store).

Particularly known are problems with the Shure SM-7B for instance, which also needs loads of gain, and if the preamp can't deliver that, an additional FetHead or Cloudlifter are normally the recommended solutions (see https://www.tritonaudio.com/fethead.html for the first and I think cheaper option).

As Musicteacher also pointed out, compression does help a bit - but with every software solution after your chain you'll also be amplifying noise, so you'll have to try if that works for you. Once you do have a strong enough signal coming in, compression will still help to get your voice come through (especially in louder environments like cars, or with open headphones or such), so this is commonly used and recommended anyway.

Hope that helps,
Wolfgang
more about me on my blog

merlyn
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Re: Trying to get microphone audio levels right

Postby merlyn » Sun Apr 28, 2019 11:42 am

I looked at the specs and this is a uni directional mic. So you'll get the maximum level when it's pointing straight at your mouth. If it's even at a bit of an angle it's 'off-axis' and the level will be reduced.

If the level is still low then you need more gain from an additional pre-amp as @wjl suggested.

sirsquid
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Re: Trying to get microphone audio levels right

Postby sirsquid » Mon Apr 29, 2019 5:54 pm

Thanks all, seems the Zoom U-22 just doesn't have enough gain for this microphone, managed to test it with the Alesis MultiMix 4 and it was able to go quite a bit louder :)

zoco
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Re: Trying to get microphone audio levels right

Postby zoco » Mon Apr 29, 2019 6:08 pm

Were did you connect your microphone with the zoom? LINE IN jack or the XLR?

And remind that your microphone impedance is 600 ohms. That is pretty high. Not all interfaces or connectors on them can handle that. Perhaps you need a pre-amp.
Shure sm57/58 for instance are 150 ohm. The difference in these kinds of impedances is the need to change the channel impedance setting a whole step on my table.

i repeat, gain-staging! So important!

sirsquid
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Re: Trying to get microphone audio levels right

Postby sirsquid » Mon Apr 29, 2019 6:13 pm

zoco wrote:Were did you connect your microphone with the zoom? LINE IN jack or the XLR?

And remind that your microphone impedance is 600 ohms. That is pretty high. Not all interfaces or connectors on them can handle that. Perhaps you need a pre-amp.
Shure sm57/58 for instance are 150 ohm.

Connected by XLR.

Well, the Zoom-U 22 specs say this:

2.6 k Ω (MIC) 484 k Ω (Hi-Z)

zoco
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Re: Trying to get microphone audio levels right

Postby zoco » Tue Apr 30, 2019 12:15 pm

sirsquid wrote:
zoco wrote:Were did you connect your microphone with the zoom? LINE IN jack or the XLR?

And remind that your microphone impedance is 600 ohms. That is pretty high. Not all interfaces or connectors on them can handle that. Perhaps you need a pre-amp.
Shure sm57/58 for instance are 150 ohm.

Connected by XLR.

Well, the Zoom-U 22 specs say this:

2.6 k Ω (MIC) 484 k Ω (Hi-Z)


And i think you connected your zoom with USB? Or with aux out? If the last one you could double check if it is connected in the right IN on your computer.

Another option is to look in Audacity and try some other interface settings. Sometimes several are available in Audacity and one is better then the other.
You could do this in the settings under Interface, but mostly there is a button on your screen in Audacity itself.
This often helped me when Audacity gave a bad IN signal with distorted signals or low volumes. Could well be your solution.

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nikgnomicradio
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Re: Trying to get microphone audio levels right

Postby nikgnomicradio » Sun May 05, 2019 1:12 am

MXL BCD-1
Polar pattern:Cardioid
Sensitivity: -54 dB re 1 V/Pa
Impedance: 600 ohms

Zoom U22
Input gain: 0 – 43 dB
Input impedance: 2.6 k Ω (MIC) 484 k Ω (Hi-Z)

Cardioid is more forgiving than a super-cardioid, but still have to keep close and on-axis with this mic

-30dB level seems low, but the zoom max gain is 10dB less than what the mic appears to want anyway
might be like other interfaces and require XLR connection for more gain
using a jack on the combination socket is often for the 'Hi-Z', for instruments with less gain

i would consider 2.6kΩ high impedance
doubt the microphone is exactly 600Ω, but that is the value usually cited for low impedance mic circuits

really need a small preamplifier between mic and the interface
only need extra 20-25dB and could get that from even cheap gear without adding noise

sirsquid
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Re: Trying to get microphone audio levels right

Postby sirsquid » Sun May 05, 2019 11:12 am

I picked up the FetHead preamp and holy cow does that thing work, but now my U-22 isn't good enough to deal with it and the volume with Gain and Output both on zero is a quite loud.

The fun continues :P


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