Home Theater Forum and Systems banner

1 - 4 of 4 Posts

·
Registered
Joined
·
2 Posts
Discussion Starter #1
I am using the latest MacOS REW version 5.19 beta 3 to display multiple distortion plots. When I try to switch some controls, nothing changes in the graph. This usually includes changing from per cent distortion to dB levels, sometimes changing the type of distortion, and rarely when changing the sources to plot.

This may all be related to having multiple controls competing with each other. There is a switch for plotting relative to fundamenta, a chooser to select between dB, dB relative and per cent.
In addition, there is sometimes option to change from per cent to dB in the top left corner of the graph. Changing the plot limits seems to be involved and sometimes messed up.

Naturally now that I am trying to write this down REW is behaving.

I just started playing with REW a couple months ago, thought is was a great program, especially for the cost, and wished it could overlay distortion plots. Soon thereafter it appeared as if by magic in a newer release. I am a little concerned that the REW contains the ability to read my mind. :surprise::laugh2:

Keep up the great work. :T: :clap:

----
Dean
 

·
Premium Member
Joined
·
6,711 Posts
Thanks, I'll take a look at that. If you come across any consistent steps to reproduce it please add them here. The mind reading technology is still under development :)
 

·
Premium Member
Joined
·
6,711 Posts
It may be worth explaining the behaviour of the 'Distortion Figures' control as it isn't as intuitive as it might be. Its main purpose is to select the format of the distortion values in the graph legend. It makes most sense when distortion is not being plotted normalised, then there is a choice of showing the dB SPL level of the distortion, or the dB level relative to the fundamental, or the percentage of the fundamental. When distortion is plotted normalised both dB SPL and dB relative give the same values, as the fundamental is treated as being 0 dB. When plotting normalised the control will also affect the Y axis, switching it between percent and dB according to the measure selected.
 

·
Registered
Joined
·
2 Posts
Discussion Starter #4
Now I am getting the same type of problems in the main distortion graph window. After playing around for a while REW started taking up to 30 seconds to refresh the distortion graphs. I had been switching the two controls and looking at various measurements.

The first plot show the distortion when I accidentally clicked on my background measurement. It shows fundamental and 2nd harmonic plotted correctly in absolute dB - background noise level around 50 dB. But the THD is shown as -8 dB. This looks more like relative THD, not absolute. I don't see how the THD can be less than the 2nd.

Next we have a plot showing the relative distortion in dB relative. Everything looks correct, but this is not what I saw in REW. The third image show a screen capture taken with REW's saved graph in front of the REW window. REW shows distortion in per cent while the saved graph correctly shows distortion in dB relative.

I still do not see any reason to have a check box for plotting distortion normalized to fundamental - it is redundant. The picker can select not normalized by selecting dB SPL. Or it can select normalized and display in either per cent or relative dB. Am I missing something?

I keep thing that some interaction between the check box and the picker is causing the problem. Another possibility is a memory allocation problem. This might explain why the distortion graphs suddenly slow down after much use.

----
Dean
 

Attachments

1 - 4 of 4 Posts
Top