Noise can be super annoying to find in an audio chain. Yours is relatively short, so it should not take too much effort to find and eradicate!
ZERO YOUR MIXER
The sample sounds like you need to check your gain stages. Most budget mixers I've encountered are noisy when channel gain is cranked. If you have headphones, plug them directly into the mixer, and see if the noise is there. If it is, try turning the gain on all channels down fully. Does it go away?
All new sessions should begin by zeroing your mixer:
- Set input gains to minimum (I anally turn all faders down too - it's unnecessary but I find it easier to mix if only the channels in use have faders up!)
- Filters set off
- EQ's set flat
- FX minimized
- Sends turned down
Another common culprit is electrical noise. I'm not hearing 60Hz hum, so unplug everything from the mixer except your headphones, and turn gains and faders all the way down. Do you hear noise then? If not, bring your faders to unity, but keep the gain down still. Should still be silent. While listening, turn gain up on each channel, one by one. Any noise introduced at this point, with nothing plugged in, is either a not so ultra quiet mixer, or electrical noise. Try plugging the mixer in to a different circuit and hear if it goes away.
THE WEAKEST LINK
If there is noise only with a microphone plugged into the mixer, try a new mic. Beg, borrow, or steal (not really, but they are cheap to rent) an old dynamic standby like a Shure SM57 or 58. Plug it in and see if you get the same noise. Remember to check your gain stages - too much gain will invariably introduce noise.
Learning how to properly set mixer levels will go a long way to preventing extraneous noise in almost all mixer related work. The golden rule is to start by zeroing your mixer, then set levels for each input (we'll use a vocal mic in this instance):
- Master bus to -0- if meters are POST master fader
- Bring channel fader to -0-
- While singing at the loudest you'll be recording into the mic, bring your gain up for that channel until meters read -0- at their peak.
Doing this for each input you'll be recording ensures that each channel is appropriately gained to maximize headroom and minimize noise. It also means you now can easily set levels between each channel (i.e. 'MIX') using only the channel faders.
SILENCE IS GOLDEN
I'll never forget the first time I was able to record silence. When DAW's were in their infancy, we didn't have fancy USB/FW interfaces, we had to go in through sound cards, which in all budget cases had really crappy and noisy A/D (SB16 anyone?). Then my first FW MOTU changed all that. OK, get off my lawn!