A Neat Experiment (O-scope and RSMeter) (1 Viewer)

[Rick Guynn]

I'm not sure if anyone has posted up info about this before (didn't do a search), but I thought I would share something I did this weekend.

I was taking readings on the bass response in my room with my sub in it's current position. Since I had everything out, I thought I would try an experiment with my sub.

I got my o-scope out (got cheap from e-bay) and hooked it up to the output from the RS meter. I played a sine wave through the sub and took a look. Sure enough, the wave shows up very nicely on the o-scope screen. Something to note though is that the image was kinda rough at first. It really became reasonably stable up in the 80+ dB range. The really neat thing was to run mains and sub around the X-over frequency and then flip the phase switch. You literally watch the wave cut in half.

Unfortunately, the amp in my current sub does not have variable phase. I really wanted to set the phase 90° out and see if two seperate waves were visible. I will be trying this as soon as I get my IB set-up (using a PE794 for that one).

I realize that you can do phase adjustment by just taking sound-level measurements, but it was really neat to actually see it on the screen.

RG

 

[Chris Tsutsui]

Hey, can somebody explain what difference is between say 0 degrees and 180 degrees phase?

I can hear a slight audible difference but it's often inconsistent and it's hard to tune phase when I don't understand it fully.

 

[Rick Guynn]

Check out this page, it might help:
Sine Waves and Phase
RG