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Old 7th December 2009, 10:18 PM   #121
gedlee is offline gedlee  United States
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Originally Posted by askbojesen View Post
The 32 bit version works on 2000, XP, Vista, 7
The 64 bit version works on Vista, 7 64 bit
The 64 bit version works fine on my 64 bit Vista machine which is now Win 7 64 bit.
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Old 11th December 2009, 06:23 PM   #122
ilardi is offline ilardi  United States
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Default Need Help Using HolmImpulse

Being pretty new to computer loudspeaker testing (and to speaker testing in general) I have a few questions about HolmImpulse. I’ve had only mixed success with this very intriguing program so far, but I think I still need to refine my testing technique. So, please be patient, but I have a few rookie questions:

1) What is the “flip frequency” that is used to set up the Square noise (MLS) test? I’m just curious about this since the default setting (.900) seems to work. I accidentally changed this to .999 once and the test signal started to sound very peculiar! I’d like to know what I did.

2) Can anyone, in 25 words or less , explain why and when I should select either logarithmic sine sweep, chirp and/or the square noise as my signal. I have tried all three on numerous occasions, and their results are almost never the same, although they do track to a certain extent in certain frequency ranges, depending on whether I am making near field or far field measurements.

3) I am also curious if there are any guides as to which type of smoothing I should use and when to use them. It seems I can turn a very ragged response into a very smooth response, clearly one can go to far with smoothing, but I don’t have good feel (ok any) for how far is too far.

I haven’t found, yet, answers to these particular questions in Testing Loudspeakers (by Joseph D’Appolito)—great book by the way—so I am appealing to the forum for help.

I would also be interested in hearing from anyone who is using an EMU 0202 USB with HolmImpulse. HolmImpulse always crashes when I close the program and occasionally during program operation. I suspect that the problem is the 0202 since if I don’t go above 44.1 khz I avoid most crashes during operation; I also think its drivers, are generally, pretty flaky. Unfortunately, Creative’s support leaves much to be desired.

TIA

Terry
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Old 11th December 2009, 07:25 PM   #123
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I agree with you ilardi about D' Apollito's testing book. Great detail on how to do the testing but, and a VERY important but - little or nothing about interpreting test results.
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Old 11th December 2009, 07:36 PM   #124
Pano is offline Pano  United States
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I think I might be able to answer some, but not all.

Use log sweep if you can. I.E. low noise or close. Use MLS for noisier environments or farther away. Chirp - have not figured that one out yet.....

Smoothing. Anything between 3rd and 12th is useful. 3rd give you a sort of general look at tendencies. That's handy. 6th or 12th shows you more detail, sometimes more than you can do anything about. Unless you have an almost perfect set-up, 12th is a jaggy as you want to go. I usually work in 6th, unless I'm looking for some little detail somewhere.

Can't say about the sound card. I rarely have crashes with my M-Auio USB card, but even its drivers are flaky. HOLM does not seem to care, tho. Maybe stop the audio stream before quitting?
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Old 11th December 2009, 09:09 PM   #125
breez is offline breez  Finland
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I think logsweep allows better signal to noise ratio than MLS. 3dB crest factor vs. practical 9dB (I think I read this in ARTA manual). Logsweep is more robust when measuring non-linear systems, but impulsive noise during the sweep may ruin the measurement.
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Old 12th December 2009, 01:50 AM   #126
ilardi is offline ilardi  United States
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Default Need still more help with HolmImpulse

Thank you skeptic43, panomaniac and breez. Another question. I have been measuring near field response in a small, vented speaker that I have built. The nearfield response of the woofer does not show the notch, that a vented speaker should show. The impedance curve I measured with WT3 looks textbook so I can't figure out why the response shows just a small inflection at fb, not at ll what I would have expected from D' Apollito. I figure I must be doing something wrong-but can't quite figure out what. Again any suggestions would be very much appreciated.
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Old 12th December 2009, 06:36 PM   #127
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I agree with you ilardi about D' Apollito's testing book. Great detail on how to do the testing but, and a VERY important but - little or nothing about interpreting test results.
D' Apollito did a long series of technical reviews of kit loudspeakers is Speaker Builder / AudioXpress magazines. In the reviews he analyzes his measurements. He found a suppressing number of design faults!
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Old 12th December 2009, 07:12 PM   #128
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D' Apollito did a long series of technical reviews of kit loudspeakers is Speaker Builder / AudioXpress magazines. In the reviews he analyzes his measurements. He found a suppressing number of design faults!
Thanks. However, my point was he should have included that stuff in the book for completeness.
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Old 12th December 2009, 09:38 PM   #129
ilardi is offline ilardi  United States
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I think it would be difficult to have provide interpretations of all potential issues. But a case in point-in support of skeptic43-is that the book, which I do use and enjoy, doesn't teach the analytic tools that would help me figure out what is going on with the measurements in my post 126. In fact, I have kind of come to the conclusion that it is not my measurement technique but rather mistakes I have made in the design of this particular prototype. But the book didn't point me to that conclusion at all. In defense of the book, however, the author does provide some useful guidance for interpreting impedance curves.
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Old 13th December 2009, 02:21 AM   #130
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Thanks. However, my point was he should have included that stuff in the book for completeness.
I think that you are right. I bet he planned on doing so, but somewhere along the line he ran out of time or enthusiasm.
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