Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Multi-Way Conventional loudspeakers with crossovers

ARTA
ARTA
Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 1st October 2019, 02:10 PM   #831
DBMandrake is offline DBMandrake  Scotland
diyAudio Member
 
DBMandrake's Avatar
 
Join Date: Nov 2010
Location: Glasgow, UK
Quote:
Originally Posted by celef View Post
Yes, i am using dual channel but still getting this error, it is like i am moving the mic just slightly back and forth between each repeated measurement, which i am not doing
Low signal to noise ratio of the reference input at low frequencies in a 2 channel config is one possibility.

Try to aim to have the signal being measured (microphone) and reference input (amplifier output ?) as near as possible to equal in level as perceived by the sound card and shown in the bar graphs in ARTA in the capture window.

In my case I measure with a Behringer UMC204HD and I am able to put the left input in mic level mode and the right (reference) input in line level mode and separately adjust their attenuators to get the levels approximately balanced between mic and reference.

If your reference signal is more than about 30dB below the mic level or is not far enough above the noise floor you will have problems. Also your reference input should be DC coupled or at least be flat down to very low frequencies as attenuating the low frequencies can cause issues with the SNR at low frequencies. (See my previous posts about this earlier in this thread)
__________________
- Simon
  Reply With Quote
Old 22nd October 2019, 08:32 PM   #832
tmuikku is offline tmuikku  Finland
diyAudio Member
 
Join Date: Sep 2004
Location: Savo, Finland
Send a message via ICQ to tmuikku
Quote:
Originally Posted by mbrennwa View Post
It does help, I often do it with MATAA before FFT of the impulse response. The relevant frequeny components are so low that the FFT has no way of discerning it from DC. Removing any DC or linear trend takes away most of the problematic low-frequency content that is not resolved in the impulse response.
Hi mbrennwa, others. Spent a better half of a day doing measurements with ARTA and noticed too late there was arbitrary DC offset / low frequency noise ruining most of the measurements... Being novice, didn't notice it before trying to simulate crossover. Live and learn. I found some of you were discussing about the same issue back in January 2019.

I don't know when I have another day off to take new set of measurements so it would be worth trying to salvage some of these.

Any tips if there was a way to clean some of the low frequency anomalies out? Checked out MATAA but it pretty much requires some custom code bulk process files from ARTA? I would be pleased if there was a tool to batch process these since full 360 hor + ver measurement sets for a huge three way speaker was commenced

I tried to find out what was causing the problem afterwards, but didn't find it out yet. Might be bad connector in my old sound card. It didn't occur on single channel measurements, only on two channel. Tried swapping between left and right, same problemo.
Thanks!
Attached Images
File Type: jpg two-channel-low-frequency-problem.jpg (406.3 KB, 210 views)

Last edited by tmuikku; 22nd October 2019 at 08:35 PM.
  Reply With Quote
Old 24th October 2019, 07:35 PM   #833
mbrennwa is offline mbrennwa  Switzerland
diyAudio Member
 
mbrennwa's Avatar
 
Join Date: Mar 2005
Location: Zurich, Switzerland
ARTA
Quote:
Originally Posted by tmuikku View Post
Any tips if there was a way to clean some of the low frequency anomalies out? Checked out MATAA but it pretty much requires some custom code bulk process files from ARTA? I would be pleased if there was a tool to batch process these since full 360 hor + ver measurement sets for a huge three way speaker was commenced
What format are the ARTA files (I have never really worked with ARTA files, so I don't know)? Maybe just send me a few examples and I might give it a crack.
__________________
------
Group buy for augerpro waveguides for Scan Speak tweeters -- elliptical version -- circular version
  Reply With Quote
Old 25th October 2019, 06:58 AM   #834
tmuikku is offline tmuikku  Finland
diyAudio Member
 
Join Date: Sep 2004
Location: Savo, Finland
Send a message via ICQ to tmuikku
Thanks mbrennwa! ARTA saves impulse responses as .pir, which seems to be some kind of binary format. Could export to ASCII text file or CSV.

Actually, I got a link to a test version of VituixCAD that has DC offset option in the Convert IR to FR tool so my problem is kind of solved. At least the low frequencies between measurements are more uniform between each other and thus more usable in VituixCAD. Still cannot rely on the bottom end but at least can do some work with the measurements now. Better to confirm good data next time before proceeding too many hours

I could send you .pir files, or export some of them to CSV if you still want to check them out?
  Reply With Quote
Old 25th October 2019, 09:25 AM   #835
mbrennwa is offline mbrennwa  Switzerland
diyAudio Member
 
mbrennwa's Avatar
 
Join Date: Mar 2005
Location: Zurich, Switzerland
ARTA
Quote:
Originally Posted by tmuikku View Post
I could send you .pir files, or export some of them to CSV if you still want to check them out?
Sure! With a little help from the ARTA makers (Ivo?) I might be able to make an import tool for PIR files. Also, and ARTA export in ASCII format would be useful to have.
__________________
------
Group buy for augerpro waveguides for Scan Speak tweeters -- elliptical version -- circular version
  Reply With Quote
Old 25th October 2019, 11:49 AM   #836
Omholt is offline Omholt  Norway
diyAudio Member
 
Omholt's Avatar
 
Join Date: Jun 2009
ARTA
I don't see to get correct measurements with ARTA anymore.
The 1/3 smoothing with ARTA doesn't look very smoothed and result is very different from REW as seen below. I'm using version 1.8.5. I am using the mic freqeancy response compensation. Edit: I had forgot to update to the latest ARTA version on this machine. Just did it, but with the same result as below.

ARTA-arta-response-png

ARTA-rew-response-jpg

ARTA-arta-frequency-compensation-jpg
Attached Images
File Type: png arta response.png (75.5 KB, 367 views)
File Type: jpg REW response.jpg (153.1 KB, 220 views)
File Type: jpg ARTA frequency compensation.jpg (148.3 KB, 219 views)

Last edited by Omholt; 25th October 2019 at 11:54 AM.
  Reply With Quote
Old 25th October 2019, 03:24 PM   #837
ente is offline ente  Germany
diyAudio Member
 
Join Date: Aug 2004
Location: NNW of Rome
Hi Omholt,

I don't understand your first statement.

For me, the 1/3 octave smoothed ARTA measurements look very plausible. Your somewhat jumbled compensation file for the microphone can be found clearly in your measurement.

The REW measurement looks more like octave smoothed.

Regards
Heinrich
  Reply With Quote
Old 25th October 2019, 06:39 PM   #838
Omholt is offline Omholt  Norway
diyAudio Member
 
Omholt's Avatar
 
Join Date: Jun 2009
ARTA
Quote:
Originally Posted by ente View Post
Hi Omholt,

I don't understand your first statement.

For me, the 1/3 octave smoothed ARTA measurements look very plausible. Your somewhat jumbled compensation file for the microphone can be found clearly in your measurement.

The REW measurement looks more like octave smoothed.

Regards
Heinrich
Thanks for the reply.
The REW measurement is with 1/3 oct. smoothing. Using 1/1 smoothing in REW would look like this:
ARTA-rew-response-2-jpg

I'm pretty certain the REW measurement is correct but I will double check with a third software I have.
Attached Images
File Type: jpg REW response 2.jpg (150.1 KB, 189 views)
  Reply With Quote
Old 25th October 2019, 06:49 PM   #839
kimmosto is offline kimmosto  Finland
diyAudio Member
 
kimmosto's Avatar
 
Join Date: Oct 2005
Location: Kuopio
That crap EMM-6 calibration file makes most of the curves. And there is no such thing as "correct smoothing". Just several different mathematical methods. Author or user chooses which one looks subjectively the best or is easiest to implement.
  Reply With Quote
Old 25th October 2019, 07:30 PM   #840
300Z is offline 300Z  Brazil
diyAudio Member
 
Join Date: May 2006
Location: Recife
Send a message via AIM to 300Z Send a message via MSN to 300Z
Smoothing does look different on REW and Arta, Arta and Holm Impulse are very similar tho.
On REW I usually stick with 1/12 smoothing.
  Reply With Quote

Reply


ARTAHide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Arta box. miklos Equipment & Tools 2 19th September 2014 08:27 PM
Help with Arta- HOLMImpulse viki_v2 Software Tools 2 12th September 2012 03:04 AM
arta vs cliowin ermes Multi-Way 0 4th March 2011 03:37 PM
ARTA - using ARTA to measure room acoustics! OMF Software Tools 0 25th November 2009 02:55 PM
ARTA help Cousin Billy Multi-Way 2 13th February 2009 01:16 AM


New To Site? Need Help?

All times are GMT. The time now is 04:35 PM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.00%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Copyright ©1999-2019 diyAudio
Wiki