Recording low level faint sounds

[T0tum]

Iam trying to record some sound disturbance using condenser mic and audio interface. Having absolutely 0 knowledge on this subject i quickly found that cranking mic gain to the max, in hope to catch everything, will make it even worse due to all the introduced noise. Sometimes i get better results with lower mic gain and some post processing after.

Could someone steer me in the right direction, maybe advise a correct workflow for recording low freq. sounds, or some plugins that i need to investigate?

[raffriff42]

Is the sound you want to record low frequency (deep), low amplitude (faint), or both?
By introduced noise, do you mean electronic noise, unwanted ambient sound, or both?
Can you post a short WAV sample?

[T0tum]

Its a footstep sound (somewhat deep) with yelling in the background. I think i lose a lot of it due to electronic noise caused by hardware gain i applied to the mic.
Here is what it looks like with mic gain turned to the max:

This clip i recorded with about +9db additional gain on band 2.

[jagabo]

Decouple the mic from the floor. That will reduce the low frequency resonances. Then get a mic with a better signal to noise ratio (low self-noise).

http://www.neumann.com/homestudio/en/what-is-self-noise-or-equivalent-noise-level

[pandy]

Small sponge jacket will reduce air (wind) distortions. Use low noise pre-amplifier (embedded in computers are usually poor in term of quality). If your budget can afford go for separate mic on usb ( https://ehomerecordingstudio.com/usb-microphones/ ), if your source is mono (typical case for microphone) you can sample same signal from microphone on two channels (stereo) - later combined in digital domain (so stereo to mono) should marginally improved quality (ADC uncorrelated noise shall be reduced by SQR(2) factor). Finally you should use directional microphone (ordinary microphone directivity can be easily improved - maybe it will be sufficient). Not sure what kind of sound disturbances you are pursuing however consider to change approach and for example use some piezoelectric microphone firmly attached to wall as good alternative to condenser microphone - mechanical coupling between microphone and some hard surface like wall or ceiling may be best approach in some cases. I use multiple times this approach to pick-up micro-vibration from for example spinning hard drives - it is so accurate that you can record HDD bearing noise (and directly read rotational speed) - i use for this piezo diaphragm https://en.wikipedia.org/wiki/Piezoelectric_speaker but if you not feel comfortable with soldering (silver plated part is very thin and easily destroyed by molten tin solder - silver dilute in solder alloy) you can use inexpensive pick-up for acoustic instruments (guitar etc) - http://www.ebay.com/bhp/piezo-pickup . Such piezo pickup should be connected to line input not microphone input (good if you can use some impedance converter - piezo will produce very high signal however it demand high impedance input - should work also with bare line-in either).
My feedback is provided on assumption that you are using computer as recording device.

[jagabo]

And it's always best to put the mic as close as possible to the sound you want to hear.

[raffriff42]

Good tips all. Also, for distant sounds, you might want to look into a parabolic mic.

[Cornucopia]

Parabolics' low freq response is inversely proportional to area (based on wavelength interference nodes), so if you need very low frequencies to be accurately captured, that won't do unless your parabolic reflector is 1.5-2 meters in diameter. (I have one).

Location, location, location.
Then quality mic with low self-noise & high sensitivity, broad flat freq resp. And adjustable (optimal) pickup pattern. And low noise pre-amp & a/d. That all translates to $$$.
As mentioned, avoid mounts or placements that accentuate coupling of bass or other interfering bands.

Scott

[T0tum]

Thanks for all the tips. Suspending my mic on rubber bands did show improvement on the graph.
However, i think i went totally wrong with the mic choice. Iam using behringer ecm8000, an omni directional measurement mic. Which is worst for what iam trying to record, due to it's small capsule size? Will something like Rode nt1-A show much improvement?

[pandy]

IMHO you can just improve directivity of this good microphone (Behringer ecm 8000) - there is plenty instructions about building directional acoustic coupling... PVC or paper pipe plus some acoustic absorber...