Beyond the Ariel - Page 540 - diyAudio
Go Back   Home > Forums > Loudspeakers > Multi-Way

Multi-Way Conventional loudspeakers with crossovers

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 6th May 2009, 05:48 PM   #5391
mige0 is offline mige0  Austria
diyAudio Member
 
mige0's Avatar
 
Join Date: Jan 2005
Location: Austria, at a beautiful place right in the heart of the Alps.
Thaks Earl - I'll take your offer - just PM me.

Michael
  Reply With Quote
Old 6th May 2009, 06:24 PM   #5392
mige0 is offline mige0  Austria
diyAudio Member
 
mige0's Avatar
 
Join Date: Jan 2005
Location: Austria, at a beautiful place right in the heart of the Alps.
Regarding signal to noise ratio for CSD measurements.

The measurements I have shown recently have been taken in doors - but with no special care to ambient noise.

I may have had roughly 40 - 45dB noise floor which leaves 45dB S/N for the measurements at 90dB SPL.

This is not great at all - but still comfortable for the intent. We don't have to be too picky in this IMO.


Furthermore you immediately see the noise floor if we change unsual 25dB scale of CSD to - say 50dB.
Its really a *floor* that is displayed, if you have a PC rumming close by also the dominat frequencies of the vent and HD as something that sticks out and does not decay.

So very easy to identify...


Michael
  Reply With Quote
Old 6th May 2009, 06:44 PM   #5393
gedlee is offline gedlee  United States
diyAudio Member
 
gedlee's Avatar
 
Join Date: Dec 2004
Location: Novi, Michigan
Michael

Since I do a cross correlation, the noise is not room noise as the measurement is immune to that, its more calculation noise and limited averaging that is the problem.
  Reply With Quote
Old 6th May 2009, 08:13 PM   #5394
mige0 is offline mige0  Austria
diyAudio Member
 
mige0's Avatar
 
Join Date: Jan 2005
Location: Austria, at a beautiful place right in the heart of the Alps.
Ok - I remember you having once said that you do not use commercial software (like ARTA for example) for your analysis but do the coding by yourself (in mathcad IIRC).

I guess the crosscorrelation you mention is related to that process?
Does it mean that the artefacts of calculation done there are not evenly spread like a "floor" - making CSD post processing from your impulse extraction less usefull as usual?

Not sure if I got your point.

Michael
  Reply With Quote
Old 6th May 2009, 08:32 PM   #5395
gedlee is offline gedlee  United States
diyAudio Member
 
gedlee's Avatar
 
Join Date: Dec 2004
Location: Novi, Michigan
They will generally appear as a floor, its not caused by room noise thats all. My room noise is quite high with no end of noise interuptions from cars, airplanes, kids, HVAC, you name it. Without noise imune signal processing the data would be quite useless.
  Reply With Quote
Old 7th May 2009, 05:18 AM   #5396
mige0 is offline mige0  Austria
diyAudio Member
 
mige0's Avatar
 
Join Date: Jan 2005
Location: Austria, at a beautiful place right in the heart of the Alps.
Courtesy Earl

OS wave guide at 0 deg:

Click the image to open in full size.


OS wave guide at 15 deg:


Click the image to open in full size.


OS wave guide at 30 deg:


Click the image to open in full size.


OS wave guide at 45 deg:


Click the image to open in full size.



48kHz Files provided by Earl I converted in CoolEdit and processed by ARTA to get CSD.
Looks pretty much excellent for me with respect to decay time


Michael
  Reply With Quote
Old 7th May 2009, 07:38 AM   #5397
xpert is offline xpert  Afghanistan
Account Disabled
 
Join Date: Apr 2009
Quote:
Originally posted by gedlee
They will generally appear as a floor, its not caused by room noise thats all. My room noise is quite high with no end of noise interuptions from cars, airplanes, kids, HVAC, you name it. Without noise imune signal processing the data would be quite useless.



Noise will have its impact regardless of cross correlation. What then is "room noise" opposed to what? Not caused by room noise but shows as a floor. Room noise is ... example given: airplanes. A bit confusing to me.

CSD is quite useless. One would have to know which deviation from ideal is critical or not. The threshold of perception, related to the graphs is where? CSD is nothing but the impulse response. To estimate the impact on audio reproduction the better way is to look at (1) amplitude over frequency and (2) group delay. CSD is nothing else, really. It's apperance leaves room for some free style interpretations. But that means nothing but confusion. Every technical info on audio transducers should be related to psychoacoustics. But it can't be done - honestly - with CSD pictures. CSDs can be compared to each other. But what does a difference tell about sound quality?

have fun
  Reply With Quote
Old 7th May 2009, 07:53 AM   #5398
Jmmlc is offline Jmmlc  France
R.I.P.
 
Join Date: Oct 2005
Hello mige0,

It seems that the window rise time of the CSD you obtained using Arta on Earl's pulses is not the same that you used previously for the CDS in your message:

http://www.diyaudio.com/forums/showt...79#post1818279

Could you indicate the parameters used to obtain those CSD:

FFT size
Window rise time
Slice shift
Smoothing

(you said in your CSD comments that the decay was excellent, could you specify the frequency above which you consider the decay being excellent...)

Best regards from Paris, France

Jean-Michel Le Cléac'h


Quote:
Originally posted by mige0

Looks pretty much excellent for me with respect to decay time


Michael
  Reply With Quote
Old 7th May 2009, 10:12 AM   #5399
Telstar is offline Telstar  Italy
diyAudio Member
 
Join Date: Dec 2007
Location: Italy
Quote:
Originally posted by xpert
CSD is quite useless.
I beg to disagree.
__________________
"The total harmonic distortion is not a measure of the degree of distastefulness to the listener and it is recommended that its use should be discontinued." D. Masa, 1938
  Reply With Quote
Old 7th May 2009, 10:38 AM   #5400
xpert is offline xpert  Afghanistan
Account Disabled
 
Join Date: Apr 2009
Quote:
Originally posted by Telstar


I beg to disagree.
Granted.
  Reply With Quote

Reply


Hide 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
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



New To Site? Need Help?

All times are GMT. The time now is 03:33 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright ©1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2