REW + UMIK-1 : RTA : erroneous low freq spectrum ?


New Member
Thread Starter
Nov 30, 2017
Newbie to this forum ... your enlighten is very much appreciated.

Just got my UMIK-1, and I am not sure why I get so much unexpected spectral reading on low freq ( < 30 Hz ) ?

The test the scenario, runs on a win10 desktop, with crappy speakers ( still betther than those on a laptop )
1) Run the REW tone generator : 1 KHz
2) UMIK-1 is about 4 feet from the speakers ( which are about 4 feet apart ).
3) Run SPL meter, and raise volume to 75dB
4) Run the REW RTA
5) Accumulated spectrum attached.


The RTA clear shows the 1KHz fundamental, and some line-frequency related noise.

What I don't understand is why are there so much energy at the low freq : < 30 Hz ?
- I don't have a sub woofer, thus don't expect much at the low end of the freq
- Can the UMIK-1 pick up at 2 Hz ?

The reason I want clarity on the low freq is that I would like to use REW + UMIK to characterize a hall : 88' x 50' x 30'.
Room of this size would have resonance freq in the single-digit-Hz.

Your enlightenment is much appreciated.
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