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 13th January 2019, 06:36 PM   #711
DBMandrake is offline DBMandrake  Scotland
diyAudio Member
 
DBMandrake's Avatar
 
Join Date: Nov 2010
Location: Glasgow, UK
What sound card do you have ? And are you using an ASIO or directsound driver ? Are you sure the sound card natively supports 192Khz sample rate ?

If it doesn't, it will be sampling at a lower sample rate and then software upsampling it to 192Khz. This will cause a reduction in quality and can result in aliasing artefacts.

You need to confirm what sample rates are supported by the sound card in hardware, and don't go above the highest sample rate supported in hardware by the card as it's important to avoid any intermediate software resampling in the sound driver or windows.

Almost certainly the issue is the sound card or it's driver. I use 192Khz 24 bit all the time with ARTA and don't see artefacts like this.
__________________
- Simon
  Reply With Quote
Old 14th January 2019, 12:24 AM   #712
dch53 is offline dch53  Australia
diyAudio Member
 
Join Date: Jun 2015
Location: Perth, Western Australia
Quote:
Originally Posted by DBMandrake View Post
What sound card do you have ? And are you using an ASIO or directsound driver ? Are you sure the sound card natively supports 192Khz sample rate ?
Thanks Simon. I'm using a Juli@ card that I no longer use in my music server. It does indeed natively support 192kHz sampling rate. From what I've read, the Juli@ seems to be widely used in this role.

I'm testing a sound card interface at the moment.

It occurred to me that I should redo the loopback test at 192kHz/131072 and as you can see below, the harmonics look pretty much the same, albeit with a slightly lower noise floor, so maybe they're contributed by the sound card.

From what you're saying, I should use the highest sampling rate my sound card supports.

Varying FFT size appears to produce different results too. Should I be using the maximum FFT size also?

I thought ARTA used the right channel as reference to cancel out sound card contributions?

Regards, Dave.
Loopback -30dB Fs 192kHz FFT 131072.png
  Reply With Quote
Old 21st January 2019, 10:42 PM   #713
DBMandrake is offline DBMandrake  Scotland
diyAudio Member
 
DBMandrake's Avatar
 
Join Date: Nov 2010
Location: Glasgow, UK
I would imagine that dual channel mode can only cancel out linear distortions (frequency/phase response errors) not non-linear distortions, and it can only cancel linear distortions to a certain degree - see my earlier posts about problems with the low frequency response being attenuated too much in the reference channel.

Do those harmonics go away if you drop the input level slightly ? Some sound cards can not input a signal all the way up to 0dB FS without some distortion, sometimes you need to drop the level (in the analogue domain before the sound card) a couple of dB. I typically take my measurements at no more than -3dB FS.

I see that your test signal is around -20dB but that could be a result of the adjustment of the input level mixer in windows, which means the pre-amps may be still getting overloaded or being operated too close to 0dB FS. Does the distortion change if you adjust the line level input mixer in windows ?

Another possible cause is the pre-amp in the sound card, especially if it's a balanced input and you are trying to feed in an unbalanced signal.

Some sound cards support this using a servo balance input, but this inevitably results in significantly higher harmonic distortion.

This is the case with my Behringer UMC204HD - if I input a balanced/floating signal via the normal front panel XLR connectors everything is fine, however if I input an unbalanced ground referenced signal (with pin 2 earthed) then although this is a supported configuration, harmonic distortion jumps up quite a lot to the point where it's marginally acceptable for measurement purposes.

However I can work around it by bypassing the pre-amps completely and injecting the unbalanced line level signal directly into the "insert" input/outputs on the rear, which by their nature are unbalanced. And as the pre-amps are bypassed any distortion and noise introduced by them is avoided as well. This gives me the lowest possible noise and distortion levels when measuring unbalanced line level signals. (Although I lose the variable attenuator on the front and pre-amp gain) Maybe your sound card supports something similar ?

Regarding sample rate, ensure that windows is not trying to resample the audio. The best way to avoid this is to set the default sample rate of windows in the sound control panel (speaker properties, advanced) to the same sample rate and bit depth you have configured in ARTA, and make sure "Allow applications to take exclusive control of this device" is ticked.

If allow applications to take exclusive control of the device is not ticked AND the sample rate is not set to the same sample rate as ARTA, windows may software resample even if the hardware supports the desired sample rate. This can cause distortion and aliasing artefacts. It's absolutely critical that windows does not get in the way and start performing any resampling. A little bit of experimentation with ARTA sound device and windows sound control panel and/or vendor supplied sound card control panel software settings may be needed to ensure this.

If the sound card supports ASIO then use that as I think that avoids most of the potential problems of Directsound.
__________________
- Simon

Last edited by DBMandrake; 21st January 2019 at 10:50 PM.
  Reply With Quote
Old 30th January 2019, 07:46 PM   #714
HighTower is offline HighTower  Netherlands
diyAudio Member
 
Join Date: Jul 2008
Quote:
There are two types of licenses:

The personal license enables the single user personal use of the ARTA Software. The price for the personal license is 79 euros.
The commercial licence enables the institutional and multi-user use of the ARTA Software. The price for the commercial license is 149 euros.
Can anyone explain this n00b what exactly are the benefits of the commercial license compared to the personal? The term "institutional" sounds somewhat familiar (Shawshank Redemption!?) and I grasp the basic idea of "Multi-User" (like multiple users on one PC? Or multiple PC's running ARTA under the same License? Or cloud based platform to share measurements and ride the Unicorns?) but besides that I'm pretty clueless honestly. Thanks in advance!
__________________
"If you can't convince them, confuse them." - Harry Truman
  Reply With Quote
Old 3rd February 2019, 08:59 AM   #715
dch53 is offline dch53  Australia
diyAudio Member
 
Join Date: Jun 2015
Location: Perth, Western Australia
Default Steps frequency response sweeps stop prematurely

Hi,

I'm working through the STEPS user manual. Setup and calibration is done.

I have the LR outputs of my Juli@ soundcard linked to the LR inputs.

Dual channel - Frequency response is selected. 20Hz to 20kHz in 1/12 octave increments. Sampling frequency is 44100 but I've also tried 96000.

After I click Start, some seemingly random number of steps is plotted and then the plotting stops. It actually got to 6092.6Hz once but it's usually much less than that.

Eventually I have to click Stop because the plot never completes.

I also notice that the generator level doesn't work the same was as it does in ARTA. The line that is plotted is always 0dB.

I confess that I do find the ARTA manuals challenging. I just want to do some simple amplifier measurements.

Any suggestions as to what I'm doing wrong please?
  Reply With Quote
Old 6th February 2019, 12:11 AM   #716
Davey is offline Davey  United States
diyAudio Member
 
Join Date: Dec 2001
Location: Bremerton, WA.
It would probably help if you posted a screen capture.

But, with that sort of simple loopback configuration in the FR2 mode, you should have an absolute straight line right across the display at 0.0db when the stepping completes.

Dave.
  Reply With Quote
Old 6th February 2019, 01:14 AM   #717
dch53 is offline dch53  Australia
diyAudio Member
 
Join Date: Jun 2015
Location: Perth, Western Australia
Quote:
Originally Posted by Davey View Post
It would probably help if you posted a screen capture.
Dave.
Hi Dave,

Thanks for responding.

Here area a couple of screenshots. They don't add much.

As you can see, on this occasion the trace stopped at 761.9Hz. Generator level is set to -3dBFS but the response is at 0.03dB. 2nd and 3rd harmonic distortion aren't displayed.

I decided to check the calibration and realised that the input sensitivity wasn't calibrated. I fixed that and it put the output level at 20.19dB with the line off the scale at the top. The trace still wouldn't complete.
Attached Images
File Type: png Soundcard loopback STEPS.png (164.5 KB, 129 views)
File Type: png STEPS calibration.png (36.9 KB, 126 views)
  Reply With Quote
Old 6th February 2019, 02:14 AM   #718
Davey is offline Davey  United States
diyAudio Member
 
Join Date: Dec 2001
Location: Bremerton, WA.
Why do you have such a huge difference in your left/right calibration value? 20db?

Dave.
  Reply With Quote
Old 6th February 2019, 09:22 AM   #719
dch53 is offline dch53  Australia
diyAudio Member
 
Join Date: Jun 2015
Location: Perth, Western Australia
Quote:
Originally Posted by Davey View Post
Why do you have such a huge difference in your left/right calibration value? 20db?
Dave.
I suspect it's because I'd calibrated the left channel but not the right. I've fixed that now but the stopping and level problems still remain.

Soundcard loopback STEPS 2.png

Re calibration: where both the ARTA and STEPS manuals state "Press the button 'Generate sine (400Hz)' and monitor the input level at bottom peak-meters." I don't get any indication of levels on the meters. I only get meter readings when I press 'Estimate Peak Input mV'.

Anyway let's ignore the levels for now and focus on the premature stopping.

More information
  • When the traces stop the output from the soundcard ceases
  • I was able to get a nearly complete trace with my soundcard interface in loopback mode:
Soundcard interface loopback -3dB.png
  • I was able to get a nearly complete test of a tube amp:
amp 1 -15dB.png
  • One amp test produced a weird glitch
amp 1 -15dB weird glitch.png
  • Increasing Fs to 96kHz results in much shorter traces before they stop.
So, making progress.

Thanks again, Dave.
  Reply With Quote
Old 6th February 2019, 03:38 PM   #720
ergo is offline ergo  Estonia
diyAudio Member
 
Join Date: Mar 2001
Location: Tallinn, Estonia
Try increasitng both the integration time and intra burst delay to 2x or 3x the value. Maybe your soundcard just does not like so short pauses between each frequency sine burst.
__________________
Ergo
  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 09:30 AM.


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