Topic: Weird Amplitude Fluctuation -- R-09HR Built In Mics

[pianogineer]

So I've got an R-09HR that I got to record my band. Mainly I use it just for practices/learning new songs, etc., so the internal mics are ok.

So tonight I made a recording at practice. We were in a garage. Just 4 of us, where 3 (harp, piano, guitar/vocals) were plugged into the same mixer with 2 monitors, and the bass was on his own amp. The mixer's speakers were about 15' apart, but pointing pretty much directly at each other. We were all running mono, so as far as I know the speakers were outputting the same signal (though I can't be 100% sure the mixer doesn't invert one or something crazy like that -- it's not my system. It's a Yamaha StagePas 300). I was on the piano positioned about 2/3 of the way between the two monitors, but offset from their connecting line by about 5 feet. The bass amp was pointed right at me. The R-09HR was set on top of my keyboard, with one mic directed towards each monitor.

So, as you can hear in the recording, there's a very weird amplitude fluctuation going on. This was recorded 24 bits, and this is the raw file (converted to mp3 in Cubase), so obviously nowhere near clipping. Mic Gain was Low, AGC/Limiter was turned off. I've heard similar stuff when I had the Limiter accidentally on and the input gain up too high, so I think I was getting weird limiting effects. The problem seems to get much worse during the louder sections of the song, though maybe it's just more noticeable there.

Is it obvious to anyone what the cause is? My best guess is some phase issue due to the fact that the two monitors were pointed directly at each other. Perhaps because I was closer to one than the other, I was getting some phase cancellation due to the 2-3 ms delay from the farther speaker?

I don't care much about this recording, but I'm going to be using the R-09HR to record a SBD feed at a gig in a few weeks, and want to make sure it's not a hardware problem (though I'm 99% sure it's not).

Thanks for the advice.

[JonG]

The sound is a little funky, but that's likely from a combination of the mic and monitor positions.  I don't hear what you hear, where in the sample do you believe there are 'weird amplitude fluctiations'?

[pianogineer]

Yeah... I was listening to it in my car the other day and it was much harder, if possible at all, to hear. When I first heard it I was playing the song in Cubase and listening through headphones, and it was very noticeable.

I think I actually first noticed it as I was looking at the waveform in Cubase, seeing the amplitude apparently fluctuate. It's noticeable to me when he starts singing and continues throughout the clip -- sounds like it's been overlaid with a sine wave adjusting the amplitude with a frequency of about 1 Hz (so about 1 phase in/out per second).