HOLMImpulse: Measuring Frequency- & Impulse-Response - Page 59 - diyAudio
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Old 5th January 2010, 11:57 AM   #581
domtw is offline domtw  France
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Hello Ask!
I am wondering what would be the upcoming improvements on HOLMImpulse in 2010 ?
- use of a reference signal (before the DUT)
- impedance measurements
- automatic minimum phase
- CSD graph
- crossover simulation

Am I dreaming ?

I like your software a lot for its stability, rapidity and userfriendlyness.
At the moment, I still use others to complete my needs...

Happy new year to you and everyone here !
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Old 21st January 2010, 01:19 AM   #582
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Default I have been a little quiet...

I have been a little quiet... I have had my reasons...

I know that. Thank's a lot for not giving up on this piece of software.

Well, Regarding new features - I don't expect much

I rather go for stabilizing and work on the manual, maybe start a wiki.
But It will not be a wiki here at DIY

I might revisit the THD calculation

I'll be back
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Old 21st January 2010, 01:27 AM   #583
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Default Comparasion with ARTA (Distortion)

Thank you very much for this testing

Quote:
Originally Posted by _Wim_ View Post
Hello Ask,

I just want to say that your software is fantastic, and that I really really appreciate it that you are supplying this tool for free, and still give better support than most software companies do for their $$$$-software. The easy of use is just amazing! With my previous tools (AMSPC from Kemsonic, Cliodos and ARTA) I had to read the entire manual before using them, AND keep the manual nearby while measuring. So far I have not yet read your manual! I am going to, but currently I am having too much fun playing just playing around with it......................
Can you attach or sent the measurement file where you have measured the distortion, then I can see what is going on ?

Quote:
In this context I was wondering is it would be possible to calculate distortion as suggested by Dr. Geddes (Gm-metric) in the following papers:
http://www.gedlee.com/downloads/Distortion_AES_I.pdf
http://www.gedlee.com/downloads/Distortion_AES_II.pdf

This would be direct visual indication of how we perceive the sound, and I think this could be very interesting to see how well it corresponds.
I don't think that we can use the logsweep for this, I will re-read and think again

Quote:
One feature I am very found of in ARTA (and I would like to see in your software as wel), is the generation of target curves (filter curves) for amplitude and phase. This way you can easily verify if your crossover of active filter works exactly as it should, and it allows you to get a good understanding what part of the phase it due to the crossover, and what part due to the driver.
Yes I could do this, I'm not much an analog-filter guy myself, but I could implement some formulas
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Old 21st January 2010, 01:30 AM   #584
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Quote:
Originally Posted by panomaniac View Post
Maybe we can get ASK to simply build in this feature. It should not be hard.
Just add a "normalize to" window and buttons for the text export.
I would love to see that!
Could you please re-explain this feature?
I guess it's something to do with FR text export?
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Old 21st January 2010, 05:42 AM   #585
Pano is offline Pano  United States
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Yes, it's to do with the FR test export.
HOLM is normalized near 0dB. Thus the exported values are near or often below 0dB.

In some speaker design software this 0dB reference is far too low. The software expects to see 80-100dB, like a real speaker SPL at 1M. So adding 80, 90 or more dB to the exported FR measurement makes the file usable in other software.

We found a work around. Add the offset to the measurement via the "Measurement Options" - "offset dB" window. That will force the graph off the chart (max is 20dB) but it works OK for export.

A "Normalize to Xdb" dialog would be handy in the export. But for the moment the work around is OK.
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Old 21st January 2010, 06:17 AM   #586
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I've hit the same issue as panomaniac. Used the same workaround.

Another little convenience feature that would be nice would be to use drop down, multi-select edit boxes instead of checkboxes for picking I/O channels. I have a 20 input, 20 output audio interface so I end up doing routing in the interface's mixer rather than in HOLMImpulse (Jack would be the software equivalent for routing). A little more flexibility in HOLMImpulse would make it play a bit nicer with the system.

I sent Thomas side by side data for HOLMImpulse and SoundEasy (and said nice things about HOLMImpulse) a few weeks back; toss me a PM if he didn't pass it on to you. Will probably have some more in the future, too.
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Old 21st January 2010, 12:52 PM   #587
_Wim_ is offline _Wim_  Belgium
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Quote:
Originally Posted by askbojesen View Post

Can you attach or sent the measurement file where you have measured the distortion, then I can see what is going on ?
Hello Ask,

I did not have the original file any more, but I made I new one (results are consistent).

Did you read my post in 580 (fade-in time)? Could it be that this is causing the problem?

Greetz,

Wim
Attached Files
File Type: zip THD.zip (101.4 KB, 9 views)
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Old 21st January 2010, 07:30 PM   #588
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Quote:
Originally Posted by _Wim_ View Post
Hello Ask,
I did not have the original file any more, but I made I new one (results are consistent).
Did you read my post in 580 (fade-in time)? Could it be that this is causing the problem?
Greetz,
Wim
No it's not the fade in-time - it is the algorithm which I use to calculate THD from the log-sweep impulse response.

See the attachment with the impulse zoomed out and on a dB scale - No Harmonic pre-impulse can be seen

From my point of view the harmonic distortion does not make sense if the noise floor is greater than the harmonics

But HOLMImpulse is misleading here... I agree and want to do better
Attached Images
File Type: png Impulse.png (35.9 KB, 275 views)
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Old 27th January 2010, 09:27 PM   #589
ghbond is offline ghbond  United States
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Default WM61A Capsules & Amplifier Calibration

I have seen the results of other tests on the web of the WM61A on the Internet. While all show some rise in the high end of the audible frequencies, the size and extension of the rise has varied. Some show only a 3 db rise, and some show the rise returning to the mean before 20 khz. Do you have knowledge of how much variation there may be in this part?

Also, I used the loopback to adjust for the variation in the sound card. I'd like to adjust for the complete loop variation. In other words, use a 1Khz tone and an oscilloscope to set the output at the speaker terminals to 1 watt, and then feed the voltage at the speaker back through a resistor divider to the microphone input, and run the D/A calibration on the entire loop. Do you see any problem with that?
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Old 2nd February 2010, 01:09 PM   #590
pof@ is offline pof@  Denmark
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Default Line-in as input device?

I have a microphone, Audyssey APM1, with the corresponding calibrated preamplifier ACP2. Unfortunately my laptop does only have a microphone input, so I need to buy myself an external soundcard with a line-in input. I intend to buy a Creatives USB Sound Blaster X-Fi Surround 5.1 but before I do I would like to be sure about this setup. Am I able to use a line-in input as the input device in HOLMImpulse?

Thanks in advance
Peter
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