Hi. I've been playing around with REW for a couple of days. At the moment I'm only measuring my soundcard interface.
It's pleasingly easy to get frequency response and distortion curves. Here's a sample:
THD at 1kHz of 0.0087%.
When I analyse a 1kHz tone in RTA and all is running well I get:
THD is shown as 0.0018%.
Why the difference when using RTA?
Now, things often don't go well. Here are a couple of images:
The trace returns to normal but what causes these errant curves? Noise?
I suspect that whatever causes these cause the same problem with the stepped sine curves. Here's what it looks like when all is going well:
but other averages produce curves like this that mess things up:
Again, noise is high some I'm guessing that's the cause. Sometimes the noise must persist for a while because the curve only gradually returns to what it should be.
Should I be looking at an external USB soundcard instead of my interal Juli@ card?
Thanks very much!
Dave.
It's pleasingly easy to get frequency response and distortion curves. Here's a sample:
THD at 1kHz of 0.0087%.
When I analyse a 1kHz tone in RTA and all is running well I get:
THD is shown as 0.0018%.
Why the difference when using RTA?
Now, things often don't go well. Here are a couple of images:
The trace returns to normal but what causes these errant curves? Noise?
I suspect that whatever causes these cause the same problem with the stepped sine curves. Here's what it looks like when all is going well:
but other averages produce curves like this that mess things up:
Again, noise is high some I'm guessing that's the cause. Sometimes the noise must persist for a while because the curve only gradually returns to what it should be.
Should I be looking at an external USB soundcard instead of my interal Juli@ card?
Thanks very much!
Dave.