missing low frequencies in curve

[juggler]

I'm brand new to REW and minidsp and am looking for some help integrating 2 subwoofers. I'm still stuck on trying to measure an accurate sweep on the first subwoofer using a Umik-1 and minidsp 2x4HD. My main question is why I'm not seeing or hearing frequencies below about 60 Hz.

When I level-matched with pink noise, I had to turn the gain dial on my sub about 75% to the max just to get 75 db and turn my receiver's main volume to -15 (I usually listen around -20). When I go to measure in REW, I'm not getting any output below about 50-60 Hz, then there's a sudden jump around 80 Hz (see attached curve). I assume I'm missing some sort of crossover/filter setting. My room isn't very big, but the back wall is only a waist-high wall and it opens up to a much larger part of the basement. So it's a difficult room, but in the past when I've just been running Audyssey XT32, and then tried test tones at 20, 30, 40 Hz..., I've heard my sub generate these frequencies pretty well.

I used all the same settings that Home Theater Gamer recommends in his minidsp tutorials. In minidsp, I have the output crossovers set to "bypassed". Receiver settings: Audyssey XT32 is turned OFF, all crossovers set to 250, "bass" set to LFE with 120 Hz LPF, sub trim level set to 0, sound mode set to "stereo". I noticed test sounds still coming from the front L and R speakers, so I turned off my external amp that powers those speakers.

Thanks for your help!

 

[John Mulcahy]

That is likely to be due to noise cancellation processing, which Windows tends to apply be default to any mic input that provides stereo data (assuming that one channel is signal and the other is background noise). Make sure enhancements are not enabled on the Windows audio input properties Advanced tab (System - Sound - Related Settings on right hand side - Sound Control Panel - Recording - select UMIK, click Properties button) or Enhancements tab. Some PCs may have a separate application with similar features, e,g, Waves MaXXAudio, HP Audio Center, myASUS.

 

[juggler]

Thanks so much for your help! Turning off the enhancements settings in my laptop for the UMIK and also the output to the Marantz completely fixed my problem. It also improved the gain issues I was having.