HOLMImpulse: Measurements in practice

[askbojesen]

The intention of this thread is to get practical feedback for my application: HOLMImpulse

HOLMImpulse is Non-Commercial freeware with full functionality (No limitations or trial periods) running on Windows XP/Vista

Download HOLMImpulse Here


Other diyaudio thread for theoretical discussions
I started a thread, which went rather theoretical:
HOLMImpulse: Measuring Frequency- & Impulse-Response
If you have theoretical questions/features/bugs/doubts then please refer to that thread.

The main goals of the application

• Measure Impulse-response
• Measure Frequency-response (Gain and Phase)
• Easy and fast to use (Simply select your soundcard and click measure)
• Work with any soundcard
• Use the latest measurements techniques without complicating the interface

I would like your response

• I know that there is no manual yet, I'm working on it...
• Please post your measurements in this thread, it would make me very happy to some measurements and it would help me improve the tool.

Why I'm doing this?
When I started building my DIY-speakers I could not find any freeware satisfying my needs.
I believe that whatever you can measure you must measure instead of fabulating...

• Does the grill make any reflections?
• Is the relative phase correct?
• Is the relative gain correct?
• Is the tweeter broken?
• How does my carpet or sofa table affect my impulse response?
• ...

Above questions can be answered by HOLMImpulse even without a calibrated microphone, since you are often only interested relative measurements (Like above)
I have attached a measurement of my girlfriend 's speakers (Rega EL8), where the manufacture had the mid/woofer out of phase in the one speaker causing the dip at 4 kHz
(It's of course resolved now...)

[schauki]

Hello!



I also use ARTA and the measurements look the same.
The handling of holmimpulse ist nice. I like it more than ARTA.
Realtime gating is cool.

acoustic phase is right with the crossovers....

To measure THD in my room is a problem, because of vibrating wood panels or dvb-s receiver....

But I think you have made your main goals!

Litte things like there is a big clear (grey) area right from the Graphs are not "perfect". But the function is the important thing.

best regards
Richard

[askbojesen]

Thank you for the feedback

Originally posted by schauki

I also use ARTA and the measurements look the same.
The handling of holmimpulse ist nice. I like it more than ARTA.
Realtime gating is cool.

Yes, the Realtime gating is learning you what reflections do to the response. Why don't you use a time window / gating on your measurement then?

acoustic phase is right with the crossovers....

What do you mean by this... ?

Litte things like there is a big clear (grey) area right from the Graphs are not "perfect". But the function is the important thing.

I cannot find this big clear (grey) area - please post a screenshot

My attached an image, which shows the same impulse-response, but with a different gating. (Notice the floor reflection with 100 cm extra path)

A new version 1.1.5.2 today makes it easier to save nice png-image-files: File > "Save Frequency- & Impulse-Response
http://www.holmacoustics.com/downloa.../ChangeLog.txt

[schauki]

Originally posted by askbojesen
Yes, the Realtime gating is learning you what reflections do to the response. Why don't you use a time window / gating on your measurement then?

To see the LF too.

An nice feature ARTA has is that the area wich is not a valid result marked yellow.
Measurement "dummys" will be happy if they put a short gate an have a flat amplitude...

What do you mean by this... ?

If you check the "phase" box, you see the "phase".
And its right. ARTA doesn't do it so good.
I have Filters 24dB/oktav LR an they will shown as 360° phase drift in the plot.
ARTA makes many phase shifts, perhaps its a handling fault by myself.
But HOML makes it right.

I cannot find this big clear (grey) area - please post a screenshot

Will post it soon.

A new version 1.1.5.2 today makes it easier to save nice png-image-files: File > "Save Frequency- & Impulse-Response
http://www.holmacoustics.com/downloa.../ChangeLog.txt [/B]

Download it soon.
The png export is nice but I ever do Screenshots and put it into "Gimp", and load it on my webspace.
So I can make it in the right size for forum (800x600 is good) and direct link it, and all users can see it well. Not everybody has an high resolution Screen.

best regards

P.S. sorry for my bad (horrible) english...

[KSTR]

Hey Schauki, nice to see you here!

Don't forget to check(bookmark out the main HOLMI thread, too.

(@Ask, you see my "campaign" is yielding the first fruits )

>> I cannot find this big clear (grey) area - please post a screenshot
I had mentioned this also (in the other thread), seems to be related to screen resolution and/or a user specified font size...
(see attachment)

- Klaus

[schauki]

Hello KSTR! - Servus Klaus.

You have the screen with the grey area - good, less "work" for me.

Your capaign is a little too late in the german forum - for me, because I'm reading here too. Bu I don't write much because of my english.
And I've installed the programm 5 min later I've read the thread.

My german is not much better than english... (remeber "magst du deine Fragen mal auf *deutsch* wiederholen" - "do you want to repeat your questions in german) I wrote it in german... austrian german...

Perhaps I should write danish??

best regards
and mfg

Richard

[KSTR]

>> Perhaps I should write danish??

Haha, Smørrebrød anyone?


>> Bu I don't write much because of my english.

The more you read and write on this forum the better your english will get, believe me.

And anyway, form follows function... this applies to conversations in foreign languages, too.

cu, Klaus

[Pano]

So what about the time window? Using automatic it usually isn't right for me, so I slide it until the frequency response window looks "right."

Any tips about using the time window?

[askbojesen]

Originally posted by panomaniac
So what about the time window? Using automatic it usually isn't right for me, so I slide it until the frequency response window looks "right."
Any tips about using the time window?

[list=1][*]Include/exclude the reflections. The problem is that the first reflection is often from the floor apprx. 100 cm extra path. 100cm corresponds to a wave length at 344 Hz, so that You cannot really trust the frequency response below 344 Hz, since no whole wave have yet played.[*]Measure in a Anechoic chamber (Or outside in the garden...)[/list=1]

The Autodetect feature in HOLMImpulse (Applied after each measurement) tries to detect the first reflection and cut this of with a time window. (Autodetect can be reapplied form the options window)

Tips? Post your measurement here perhaps with autodetected window and with our own selected window.

[Pano]

Well with the latest version (v1.1.5.2) it seems to be better. Also - oops! - I found that the time window was "locked." Unlocking it in the measuremant window options helped. It tends to pick about 100Hz as the low point, instead of ~300Hz as before.

But I think that recalibrating my sound card would be a good idea. Interested to know what others have done with calibration.

My current setup is:
USB>M-Audio Duo>Spdif>DCX2496>amp>speaker

I calibrated the M-Audio card with line out patched back to line in. Very flat. But I think I need to go thru the DCX (all filters off- delays on) and into the mic input of the M-Audio (padded) to get a really good cal. Or do delays make any difference?

What do you think?