I've bitten the bullet, after more than a year of guidance from seniors at DIYaudio and Gooroo Angshoo. I've decided to learn how to use a software program to measure driver parameters, optimise a passive xo, and design my own speakers. And as expected, I'm stuck pretty early in the process.
I'm using MS Windows XP Home and Speaker Workshop on a 2GHz laptop. My sound card is the Creative Digital Music MP3+ USB. It has RCA line ins, RCA line outs, plus a mono mic in (with phantom power) and headphones out. It works in full duplex.
I've built a loop cable, and tested it with a DMM to ensure that the signal from the left lineout actually is directly connected to the line ins (left and right). I've read the Unofficial Speaker Workshop Manual v1.0 (first part on calibration and config), and I've successfully done a "Record" through Speaker Workshop with sine waves. When I do a "Loop Record" and play with the mixer's volume settings, I get to set the amplitude correctly such that there's no clipping. See the screen shot here:
[IMGDEAD]http://www.starcomsoftware.com/tmp/personal/photos/sine.gif[/IMGDEAD]
Therefore I'm certain that my loop cable is working, and also that Speaker Workshop works smoothly with my sound card to play and record signals. When I try to do a "Record" using MLS, I get a strange graph:
[IMGDEAD]http://www.starcomsoftware.com/tmp/personal/photos/mls.gif[/IMGDEAD]
As you can see in the bottom left of the image, the VU meter is showing very large amplitude signals. (I subsequently cut the volume in the mixer and got the MLS signal to stay within reasonable limits --- i.e. no clipping.) However, I can't see any trace of the signal in the graph. Where is the signal? What am I doing wrong?
And when I try to use the impedance jig to measure a test resistor, it doesn't give me any reading at all.... it just shows me no reading, i.e. zero impedance.
Angshu told me to try changing the latency settings. I've tried all latencies from -20 to +20 or so. No luck.
If the VU meter is reporting high amplitude signals, why can't I see it in the graph? I thought perhaps the high-amplitude pulse is to the left of the origin of the graph, so I changed the min-max range of the X-axis in "Chart Properties" to start the graph from -20msec onwards. I thought zooming in to a small part in the beginning of the time period would help, so I changed the range (X-axis) from -20ms to +50ms. I also switched off all vertical grid lines and tick marks, so that no pulse of the graph would be hidden behind these lines. No luck. The graph is absolutely devoid of any pulses other than that tiny one after about 20ms.
Please help.
I'm using MS Windows XP Home and Speaker Workshop on a 2GHz laptop. My sound card is the Creative Digital Music MP3+ USB. It has RCA line ins, RCA line outs, plus a mono mic in (with phantom power) and headphones out. It works in full duplex.
I've built a loop cable, and tested it with a DMM to ensure that the signal from the left lineout actually is directly connected to the line ins (left and right). I've read the Unofficial Speaker Workshop Manual v1.0 (first part on calibration and config), and I've successfully done a "Record" through Speaker Workshop with sine waves. When I do a "Loop Record" and play with the mixer's volume settings, I get to set the amplitude correctly such that there's no clipping. See the screen shot here:
[IMGDEAD]http://www.starcomsoftware.com/tmp/personal/photos/sine.gif[/IMGDEAD]
Therefore I'm certain that my loop cable is working, and also that Speaker Workshop works smoothly with my sound card to play and record signals. When I try to do a "Record" using MLS, I get a strange graph:
[IMGDEAD]http://www.starcomsoftware.com/tmp/personal/photos/mls.gif[/IMGDEAD]
As you can see in the bottom left of the image, the VU meter is showing very large amplitude signals. (I subsequently cut the volume in the mixer and got the MLS signal to stay within reasonable limits --- i.e. no clipping.) However, I can't see any trace of the signal in the graph. Where is the signal? What am I doing wrong?
And when I try to use the impedance jig to measure a test resistor, it doesn't give me any reading at all.... it just shows me no reading, i.e. zero impedance.
Angshu told me to try changing the latency settings. I've tried all latencies from -20 to +20 or so. No luck.
If the VU meter is reporting high amplitude signals, why can't I see it in the graph? I thought perhaps the high-amplitude pulse is to the left of the origin of the graph, so I changed the min-max range of the X-axis in "Chart Properties" to start the graph from -20msec onwards. I thought zooming in to a small part in the beginning of the time period would help, so I changed the range (X-axis) from -20ms to +50ms. I also switched off all vertical grid lines and tick marks, so that no pulse of the graph would be hidden behind these lines. No luck. The graph is absolutely devoid of any pulses other than that tiny one after about 20ms.
Please help.