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Old 21st November 2012, 01:29 PM   #651
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Quote:
Originally Posted by NEO Dan View Post
Your the Doctor, let's see the "x-rays"...
Check out post #602. What does the impulse response tell you about the speaker being tested?
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Old 21st November 2012, 02:51 PM   #652
gedlee is offline gedlee  United States
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Quote:
Originally Posted by speakerdoctor View Post
BUMP! C'mon H.I. experts!
The reason that we tend to not to use the impulse response directly is because it is very difficult to make interpretations. There is no real way to determine what each dip and peak means.

It is easy to state what an ideal impulse would look like and hence any deviation from this is less than ideal. The ideal impulse response of a loudspeaker is a doublet - a peak up followed by an equal size peak down. It can also be said that the longer the tail is the less desirable.

If a large perturbation occurs at some time after the doublet, then the delay time can often be useful in finding out where this errant signal is coming from.

Bottom line is that the impulse response is necessary for finding where to "window" the data, but past that it takes a lot of experience to see much more than that directly in the time domain.
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Old 22nd November 2012, 11:01 AM   #653
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I'll stick my neck out and say the I.R. in post #602 shows a nice peak @ 0 seconds followed by an equal size dip (doublet Earl?), followed by another small peak (drivers in phase?).
My I.R. show a consistent blip at around 4 ms. That's my first reflection and I window below that of my FR's.

John Atkinson seems to have much to say about I.R.s when he does his measurements.
Here's a typical I.R. comment from J.A. (on the left):

"The RTi A3's step response on the tweeter axis (fig.7) shows that both drive-units are connected in positive acoustic polarity, and :implies that the best integration of the two will occur just below the tweeter axis."

Fig.7 Polk RTi A3, step response on HF axis at 50" (5ms time window, 30kHz bandwidth).

Here's another J.A. step response comment for a 3-way speaker (on the right).
"In the time domain, the SS-AR2's step response on the tweeter axis (fig.7) indicates that the tweeter and midrange units are connected in inverted acoustic polarity, the woofers in positive polarity, and that the tweeter's output arrives first, followed by the midrange's and then the woofers'. However, the fact that the decay of each unit's step blends smoothly into the start of the step of the next unit lower in frequency correlates with the excellent frequency-domain integration of their outputs seen in fig.3, and implies optimal crossover design."
Attached Images
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File Type: jpg JASonyfig7.jpg (19.4 KB, 448 views)
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Last edited by speakerdoctor; 22nd November 2012 at 11:10 AM.
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Old 23rd November 2012, 10:27 PM   #654
gedlee is offline gedlee  United States
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Sure you can tell huge things like driver polarity from the impulse response (the derivative of the step response) - thats a no brainer. Its trying to find the more subtle things in the response that gets very difficult in the time domain.
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Old 21st December 2013, 05:17 PM   #655
xrk971 is offline xrk971  United States
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Quote:
Originally Posted by speakerdoctor View Post
BUMP! C'mon H.I. experts!
I think the fewer the squiggles the better. Ideal is one up and minimal overshoot or ringing. It should look something like the logo for Holmimpulse.

Here is the response from my speaker:

Click the image to open in full size.
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Old 24th January 2014, 08:26 PM   #656
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Default Holmimpulse and JAVA update

Since I updated JAVA (now ver. 51) and am no longer able to use Holmimpulse. It gets through the initialization screens and then kicks me back to the windows systems (Windows 7). I reloaded Holmimpulse and the problem remains.

Is anyone else having this difficulty?
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Old 24th January 2014, 10:12 PM   #657
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I've had problems with win7 and corrupted save files/prefs files in Holm.

Have a look under c:\users\yourusername\AppData\Roaming\HOLM Acoustics\Holm Impulse

Make a backup of the files there (in case it isn't the problem, and also because the zip file has your most recent measurements in it) and then delete them all. Try starting holm up again and hopefully it should work.

It will have reset to defaults and your measurement files will be gone, These can potentially be retrieved by unzipping and re-importing individual measurements.

Hope that helps!

Tony.
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Old 24th January 2014, 10:33 PM   #658
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Tony, you are genius!

I had noticed an instability issue on Win 7 (and not Win XP). It may not have been triggered by the new JAVA, I was only guessing. Anyhow, things now work and I am very grateful for your advice.
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Old 25th January 2014, 01:52 AM   #659
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Glad it worked! Hope you didn't lose any measurements that you wanted to keep. I now routinely do backups from within holm with date of measurements and descriptive name so that I can find project related measurements in the future

Tony.
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Old 9th February 2014, 04:29 PM   #660
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is there a simulation program using given parameters of loudspeakers, without measuring tools or if I don't have measuring tools?
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