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 28th October 2019, 01:50 PM   #871
mbrennwa is offline mbrennwa  Switzerland
diyAudio Member
 
mbrennwa's Avatar
 
Join Date: Mar 2005
Location: Zurich, Switzerland
ARTA
Quote:
Originally Posted by iMat View Post
It is impossible to fulfill your request as manufacturer of microphones does not give true frequency (or impulse) response. They give difference from reference microphone.
Most microphone frequency response curves are indeed determined relative to some reference microphone, for which the response is "known". But the curves are just the delta to the raw reference microphone output, but rather the delta relative to the "known" reality (i.e., relative to the compensated reference microphone). Some labs also have direct ways to measure the frequency response (like the EarthWorks "spark method").

In practice it is certainly possible to calibrate an impulse response measurement such that it represents the "true" response as it was before it was captured and processed by the microphone; I guess this is what ARTA does. Of course one needs to be aware that uncertainties of the "microphone calibration curve" will also exist in the result.
__________________
------
Group buy for augerpro waveguides for Scan Speak tweeters -- elliptical version -- circular version
  Reply With Quote
Old 28th October 2019, 06:56 PM   #872
ScottG is offline ScottG  United States
diyAudio Member
 
Join Date: Feb 2003
Location: US
Quote:
Originally Posted by iMat View Post
It is not band representation, as in RTA, which you can choose in Graph Setup dialog by setting combo box Frequency Axis-> Type to "Octave bands"

Ivo
Oh, Ok.

That is what *I call "classic octave-band" (either vertical bar chart or the less known stepped chart) - and it's what I would expect (in a smoothed variation) for a given octave representation.

*and I don't think I'm alone on this after having done a search on: "classic octave-band".

Below is an in-room 1/3rd stepped (..in reference to Martin Colloms). Note that it still only has 4 different pressure levels between 1 and 2 kHz. Though very fine in detail, that's not what I see when looking at the Arta graph previously mentioned.
Attached Images
File Type: jpg 692C100fig06.jpg (33.3 KB, 278 views)
__________________
perspective is everything

Last edited by ScottG; 28th October 2019 at 07:16 PM.
  Reply With Quote
Old 28th October 2019, 07:34 PM   #873
JohnPM is offline JohnPM  United Kingdom
diyAudio Member
 
Join Date: Oct 2008
Quote:
Originally Posted by iMat View Post
Your first assumption is ok, just we need to sum power response, and do proper scalling for power od PSD mode.

For details, read AES paper:

Vanderkooy, J., Aspects of MLS Measuring Systems, J. Audio Eng. Soc., vol. 42, April 1993.

ARTA does similar procedure.
That paper (from 1994, a small typo) seems more concerned with distortion effects, I didn't come across a discussion of smoothing in it (or in the 1989 paper with Douglas Rife). My concern with approaches that use such a form of band filtering for fractional octave smoothing is that they amount to implementing low pass filtering of the sampled frequency response data by a smoothing kernel which is close (Butterworth bandpass) or identical (brickwall) to a simple moving average or box smoother. Moving average has a very poor response, with the first sidelobe more than 20% and a slow sidelobe rolloff, so the smoothed output has components that are much higher in bandwidth than the smoothing fraction would imply. Taking a log spaced data set at 96 PPO as an example, smoothing to 1/3 octave implies a low pass filtering of that 96 PPO data set with a 3 PPO cutoff and ideally components that are above 3 PPO would be heavily suppressed. Zero phase low pass filtering in the sampled frequency domain is required and moving average is a very poor way to achieve that.

It is a little odd that standards bodies do not appear to have set out conventions for fractional octave smoothing of frequency domain data, if they have I'd be interested to see that. The old "AES-X70 Smoothing Digitally-derived Frequency Response Data on A Fractional Octave Basis" project did not seem to come to any conclusions.
  Reply With Quote
Old 28th October 2019, 09:58 PM   #874
iMat is offline iMat  Croatia
diyAudio Member
 
Join Date: Sep 2014
Location: Croatia
Quote:
Originally Posted by JohnPM View Post
That paper (from 1994, a small typo) seems more concerned with distortion effects, I didn't come across a discussion of smoothing in it (or in the 1989 paper with Douglas Rife).
Sorry John,
I send you wrong paper reference. It should be:

Lipshitz, Scott and Vanderkoy: Increasing the Audio Measurement Capability of FFT Analyzers by Microcomputer Postprocessing", JAES, September, 1985.

Ivo
  Reply With Quote
Old 28th October 2019, 10:41 PM   #875
ScottG is offline ScottG  United States
diyAudio Member
 
Join Date: Feb 2003
Location: US
(PDF) Increasing the Audio Measurement Capability of FFT Analysers by Microcomputer Post-Processing
__________________
perspective is everything
  Reply With Quote
Old 28th October 2019, 11:08 PM   #876
iMat is offline iMat  Croatia
diyAudio Member
 
Join Date: Sep 2014
Location: Croatia
Hi,
I made an FFT analyser in 1985. It was two channel device. I used it several years but it has never become commercial product. At the same time a single channel system MLSSA become widely accepted in loudspeaker design. It was much cheaper than HP dynamic analyser or B&K Fourier analyzer. Later I have made ARTA software with intention to merge best things from MLSSA and Fourier analyzers.
I have implemented classical octave band presentation in real-time modes in ver. 1.9.2 (SPA, FR1, FR2) but not in Smoothed FR window, where only sweeped band analysis is presented.

Ivo
  Reply With Quote
Old 29th October 2019, 10:02 AM   #877
JohnPM is offline JohnPM  United Kingdom
diyAudio Member
 
Join Date: Oct 2008
Quote:
Originally Posted by iMat View Post
I send you wrong paper reference. It should be:

Lipshitz, Scott and Vanderkoy: Increasing the Audio Measurement Capability of FFT Analyzers by Microcomputer Postprocessing", JAES, September, 1985.
Very enjoyable read Ivo, thank you. Wish I'd come across it twenty years ago. As an aside, REW's log spaced conversion uses zero phase filtering of the linearly spaced frequency response to limit its bandwidth to 48 PPO then the filtered response is sampled at 96 PPO. Developing a method for fast fractional octave smoothing of linearly spaced frequency data made that a more straightforward option.
  Reply With Quote
Old 30th October 2019, 01:31 PM   #878
tthorsten is offline tthorsten  Germany
diyAudio Member
 
Join Date: Nov 2008
thumbs up
  Reply With Quote
Old 12th November 2019, 06:11 PM   #879
ente is offline ente  Germany
diyAudio Member
 
Join Date: Aug 2004
Location: NNW of Rome
Default ARTA 1.9.3

New release available.

ARTA 1.9.3 is available for download.
You can find the changes under news: ARTA News

Regards
Heinrich
  Reply With Quote
Old 12th November 2019, 06:35 PM   #880
mbrennwa is offline mbrennwa  Switzerland
diyAudio Member
 
mbrennwa's Avatar
 
Join Date: Mar 2005
Location: Zurich, Switzerland
ARTA
Quote:
Originally Posted by ente View Post
New release available.

ARTA 1.9.3 is available for download.
You can find the changes under news: ARTA News
"The format of PIR files is changed. Marker and cursor positions are saved in PIR files. They can be loaded on File->Open command if that action is defined in dialog opened with command File->Options."


Does that mean there are some new fields in the header section? Or does the marker / cursor data go to previously existing fields that were not used?

I am asking because changing the format might break PIR import functions in other software. That wouldn't be nice.
__________________
------
Group buy for augerpro waveguides for Scan Speak tweeters -- elliptical version -- circular version
  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 11:06 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