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Old 1st October 2009, 07:15 PM   #111
Key is offline Key  United States
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I haven't gotten back into this much - just other more pressing experiments taking up my time - and I haven't come up with a simple way of doing it yet. But basically I think what we need - provided we have a reference mic and ADC/DAC - is a way to take an impulse reponse and do an inverse covilution that acts only on the phase response and disregards the FR. So how would we get rid of the FR from an impulse reponse leaving just the phase? Manually editing the file somehow?
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Old 6th October 2009, 06:29 PM   #112
Key is offline Key  United States
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Maybe someone can help me with these measurements. I am trying to test 32-bit float converted to 24-bits and truncation vs dither at these bit-depths. At first I was just trying to import and compare the 2 files but it didn't seem to show me much. I came up with this instead and am not sure if the measurements are useful or I am interpreting them correctly.

I took 10 secs of a master of one of my songs rendered at 32-bit float. I then male a copy of the file convert it to 24-bit and then convert it back to 32-bit float. I take the original and invert mix it with the altered file which I would think only leaves the difference between the two files - noise and distortions. I then take that difference file and compare the original to it using Holm. I get these results.

Click the image to open in full size.

Green = Dithered
Red = Dithered
Blue = Truncated

Am I wrong in assuming that the truncated example has less noise (for the most part) than the dithered examples?
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Old 6th October 2009, 06:45 PM   #113
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Quote:
Originally Posted by Key View Post
Maybe someone can help me with these measurements. I am trying to test 32-bit float converted to 24-bits and truncation vs dither at these bit-depths. At first I was just trying to import and compare the 2 files but it didn't seem to show me much. I came up with this instead and am not sure if the measurements are useful or I am interpreting them correctly.
Perhaps you want to try the 2-channel correlation?
Options > 'Import response from file' > 'Signal & Recording'

Signal wave-file should be your original wave file
Recorded wave file should be your modified wave file

Then also try the dB-option for the impulse response

Like I did here with mp3-files:http://www.diyaudio.com/forums/software-tools/144984-holmimpulse-measuring-frequency-impulse-response-post1913539.html

Click the image to open in full size.
Click the image to open in full size.
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Last edited by askbojesen; 6th October 2009 at 06:47 PM.
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Old 6th October 2009, 06:47 PM   #114
Key is offline Key  United States
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That is how I did it. It's just that I did the invert cancellation prior to the correlation. The correlation on it's own was a little hard to interpret without the inverse cancellation prior to correlation. Basically if I don't do the invert isolation all I get is a perfectly flat FR and PR.

Last edited by Key; 6th October 2009 at 06:52 PM.
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Old 6th October 2009, 07:06 PM   #115
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Quote:
Originally Posted by Key View Post
That is how I did it. It's just that I did the invert cancellation prior to the correlation. The correlation on it's own was a little hard to interpret without the inverse cancellation prior to correlation. Basically if I don't do the invert isolation all I get is a perfectly flat FR and PR.
Ok, sorry - did not read enough, Yes you get should get perfectly flat FR and PR. But if you choose dB scale on the IR - and zoom in - you should be able to see a difference in the correlation?
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Old 6th October 2009, 07:21 PM   #116
Key is offline Key  United States
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I do remember zooming in and seeing spikes before but I guess it just wasn't looking as easy to interpret as my other method. I am not sure what you are saying about the dB setting. You mean the one under options after you take a measurement?

Anyway here is what it looks like if I correlate without doing the cancellation first.

Click the image to open in full size.
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Old 6th October 2009, 07:39 PM   #117
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Quote:
Originally Posted by Key View Post
I do remember zooming in and seeing spikes before but I guess it just wasn't looking as easy to interpret as my other method. I am not sure what you are saying about the dB setting. You mean the one under options after you take a measurement?
Thanks for the graphs!

I mean the little dB Checkbox in the lower right corner of the IR

I believe what we see here is the noise floor of the file- this is how much the new file correlates to the original.

If you correlate the original with the original we should not get any noise at all
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Old 6th October 2009, 09:34 PM   #118
Key is offline Key  United States
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Thanks, found it. I keep forgetting that is there.
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Old 30th November 2009, 07:20 PM   #119
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Quote:
Originally Posted by askbojesen View Post
Does the 32 bit versions work on Vista 64 bit???:
HOLMImpulse-1.1.6.6.msi or HOLMImpulse-1.1.6.6-sse2.msi
work on Vista 64? I thought you needed a special 64 bit compiled version.

No pre impulses from the harmonics
1. The measurement save length must equal the signal length
2. You must use log-sweep
3. Try ZoomOut and the dB scale

NB: In the next version of HOLMImpulse you will get an option to autosave the direct correlation as a wavefile for your own analysis

Perhaps post the graph?
What is the latest situation on Vista64 (apart from that its dead). Should I use the normal WIndows (2000, XP, Vista, 7) version or the "x64" version?
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Old 7th December 2009, 09:35 PM   #120
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Quote:
Originally Posted by Duck-Twacy View Post
What is the latest situation on Vista64 (apart from that its dead). Should I use the normal WIndows (2000, XP, Vista, 7) version or the "x64" version?
The 32 bit version works on 2000, XP, Vista, 7
The 64 bit version works on Vista, 7 64 bit
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