Exploring Visual Analyser (VA) - Page 2 - diyAudio
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Old 25th May 2012, 03:05 AM   #11
Pano is offline Pano  United States
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Don't have an answer to the DC removal thing quite yet. It seems only to work on the built in mic of my laptop. With an M-Audio card it seems not to matter.

I spent some time with the Spectrum Analyzer running in 1/3 and /16th octave mode, dual channel. I got the bright idea on looking at a microphone on channel A and the line level signal on B. By watching them jump around on music, it gave me a good idea of hot spots or holes. Not test signals or noise, real music.

Once the levels between mic and line were matched, it was pretty cool to watch both at different integration times (averages). If the mic (and thus speaker + room) was consistently different I made EQ adjustments. The sonic results are rather good, I must say.
Being able to see both channels at once was a big help and V.A. was great for that. Lines mode made it easy to see both.

If only V.A. had a channel delay, it would be great for getting the acoustic and electrical synced right up. I could not find one, but the method seemed to work well anyway.

The programming is top notch, for sure. I think he's done a fantastic job on the display traces, they look almost as as good a CRT.
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Old 25th May 2012, 03:16 AM   #12
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Very nice tutorial, Terry! I installed it on my computer last year, but never got around to actually using it, something you have inspired me to correct.

OT: Poking around your site, I discovered my Holy Grail. Really superb stuff on flutes, and I sorely wish I could afford one of your instruments! After nearly 50 years of hacking on the instrument, it's the first time I've felt that a hardware change would really improve my playing.
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Old 25th May 2012, 03:27 AM   #13
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You said on your page:
Quote:
There is also a second little window at the right of the horizontal slider, but its function is not yet clear to me, other than it is related to time and not amplitude (?).
I don't see any little window to the right of the slider on my version. Am I not looking hard enough?
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Old 25th May 2012, 04:00 AM   #14
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Pano, I only see the little window when its not "Calibrated". You can try the Default Config to go back to being uncalibrated if you want. It's probably not that important.

On the Channel delay issue you mentioned earlier, there's something of that nature on the main Settings window. I haven't investigated it yet.

I imagine the DC Removal issue will become clear as we journey on. If not, it probably doesn't matter!

Thanks for trying!

Terry
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Old 25th May 2012, 04:06 AM   #15
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Quote:
Originally Posted by SY View Post
Very nice tutorial, Terry! I installed it on my computer last year, but never got around to actually using it, something you have inspired me to correct.
I suspect many are in that boat, Sy. I certainly loaded it some year or more back, had a quick sniff around and put it in the too-hard basket. I'm enjoying delving, now that I've made some headway.

Quote:
OT: Poking around your site, I discovered my Holy Grail. Really superb stuff on flutes, and I sorely wish I could afford one of your instruments! After nearly 50 years of hacking on the instrument, it's the first time I've felt that a hardware change would really improve my playing.
Thanks! I really enjoy flute making, it's probably been the most demanding thing I've ever done, and I've done lots! Now I'm bending more towards flute research, which means I've had to upgrade my audio facilities, which is what brings me to VA, and diyAudio. Funny how journeys evolve....

Terry

Last edited by Terry McGee; 25th May 2012 at 04:22 AM.
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Old 25th May 2012, 05:06 AM   #16
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Quote:
Originally Posted by Terry McGee View Post
On the Channel delay issue you mentioned earlier, there's something of that nature on the main Settings window. I haven't investigated it yet.
Oh yeah, there it is - duh! Given in samples. It works just like it should. Thanks!
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Old 26th May 2012, 12:50 PM   #17
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OK, next article in the Exploring Visual Analyser series. In this one we finish our exploration of the Scope section by bringing in the second channel, and finding out all the things we can do with two.

Visual Analyser-The Second Channel

As usual, check it out and come back to me with criticisms, fawning adoration, etc!

Terry
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Old 26th May 2012, 01:21 PM   #18
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Terry, I like your writing! Not much to add, but I think that the example of differential mode by measuring across a resistor, though perfectly true, isn't much use on an AC coupled system. In fact, I can't remember ever using a hardware scope in differential mode, and I do that a lot, while AC coupled. As for A cross B and B cross A, I haven't explored them, but once you have A/B and B/A, multiplication functions are often not included. It's too easy to get over range. I know there are two channel cross correlation functions on some analyzers- could it be something like that? I can't imagine that Alfredo wouldn't have just used A X B if that's what he was doing. IMO, a really useful function would be if one could measure current with one channel and voltage with the other, than display instantaneous power. That's then the path to both watts and VA and knowing the difference.
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Old 26th May 2012, 01:40 PM   #19
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Nicely done, Terry. And thanks for not knowing what the A cross B does, I couldn't make sense of it and was feeling stupid. Maybe I'll take some time to figure out what it does.
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Old 26th May 2012, 04:50 PM   #20
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Here is a site with a bunch of articles on the VA. Unfortunately all in Italian, but still informative. Come on all you Italian speakers, help us out here!
http://casa.accattatis.org:9090/Arti...0on%20VA/?date
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