Home Theater Forum and Systems banner
1 - 3 of 3 Posts

·
Registered
Joined
·
179 Posts
Discussion Starter · #1 ·
Hi Guys,

I was looking to add a couple lines to a GD graph of a sub I'm measuring. I've got the GD chart and wanted to add a 1 and 1.5 cycle line to it similar to what Ilkka does here ..



Any idea how that line was added? I've tried a bunch of different things but can't seem to figure it out.

Thx
 

·
Premium Member
Joined
·
6,711 Posts
A one cycle group delay curve would follow a 1/f profile, i.e. 100ms at 10Hz, 50ms at 20Hz, 10ms at 100Hz. REW cannot show that for you, but some synthetic response data can be generated with the desired group delay that can be viewed in the group delay overlays graph. As group delay is the slope of phase you need a response whose slope varies according to the integral of 1/f, which is ln(f). I've attached a spreadsheet that calculates that, you can change the number of cycles in cell B1 and save the response as tab delimited so that REW can import it as a measurement. An example for 1 cycle of delay from 5Hz to 200Hz is attached.

View attachment gd.txt

View attachment gd.xls
 
1 - 3 of 3 Posts
Top