90-95db below 200HZ for noise floor

[westrock2000]

I am still trying to figure out to use the Omnimic software. When I have it just idle, I am seeing 90-95db of low end noise in the most quite room in the house (quite enough that I can hear the blood flow in my ears).

Is this expected? This was actually done with the microphone under a pillow (hence the drop off on high frequencies).

That just seems really loud for background noise.

[westrock2000]

For sanity, I went outside and did a measurement. SInce there was some light wind, I stuck in the mic in the trash container and this is the measurement I got. Very low noise on mid to high, but 90-95 on the low still.

[westrock2000]

I installed REW and in the same room using the Omnimic mic with the calibration file this is the noise floor I get....this seems much more believable.

This is on WIndows 8 with Omnimic executable set to run in WinXP SP3 environment.

[westrock2000]

I loaded up Windows XP in Virtualbox and Omnimic software crashes before loading. Installed Vista in virtualbox and it seems to be working fine, but I get the same response curve, with 200Hz and less being +40db higher then mid and high frequencies.

[Derekj]

Mine started doing the same thing a few weeks ago - i sent my mic to PE to get it checked. Should hear back from them in the next week I hope.

[westrock2000]

I'm thinking its software related because I ended up doing measurements in REW and it was no where to be seen, but the upper frequency stuff looked same.

[dcibel]

In your Omnimic screenshots you have the gain (slider in top right) set as low as it can go. Maybe increasing the gain can help?

For best results, the input sensing gain of OmniMic should be adjusted approximately for the sound level. The input gain slider control is at the top right of the OmniMic screen.


The slider should be set so that gain is not too low (which would limit dynamic range) and not too high (which might overload OmniMic's electronics).


When a sound level is sensed that is too high for the OmniMic, a message and a small red dot will appear to the right of the slider -- if you see this, move the slider to the left to reduce the gain until the red dot no longer appears.


The gain can instead set to adjust automatically by the OmniMic software if you temporarily put a check in the small box next to the slider. Expose the OmniMic to the sound level that will be used for several seconds, and the slider should adjust to a compatible level.


It is best NOT to leave the auto gain button checked during measurements, though, since the slider movement can interfere with ongoing measurements. After the proper level has been found, uncheck the box.

[4thtry]

I agree with dcibel that this looks like some type of a gain issue. My OmniMic has much lower readings in the bass, but has roughly the same downward slope when I cover it with a pillow in a quiet room (see attached graph). Also, double check your Control Panel level setting. My experience has been that the Control Panel "level" setting can mysteriously re-set itself from time to time.

Bill S.

[Derekj]

Just a quick update - after almost a month my OmniMic is on it's way back to me and has been repaired. What was wrong with it I don't know yet but I will see how it measures when I get it back next week. (Took so long because the guy that tests them was on holidays)

Update - got my mic back - looks like to me that they might have replaced it - serial # is different. Plugged it in and the low end garbage is gone - levels are down to what it should be! Thanks PE!!