Behavior of black curve in parametric equalizer parameter window

I continue with my search of the meaning of the black curve and blue shaded area in the parameter window :

When I added a general low pass of 5000 Hz to my equalizer block I got picture sgbrt4a.JPG : ok

When I close and reopen the parameter window I get picture sgbrt4b.JPG ??

If I change the low pass frequency to 1000 Hz the picture sgbrt4c.JPG looks reasonable.

When I close and reopen the parameter window I get picture sgbrt4d.JPG ??

When I change now the frequency back to 5000 Hz i will get sgbrt4e.JPG ??

If I close et reopen the parameter window I see something like on sgbrt4a.JPG ok.

I am working with version 3.1 Build 20 rev 375 and Windows XP SP3.

Kind regards

Peter Greuter

I am not able to recreate the problem you're showing here. Have you tried to simply delete the parametric EQ block from your design and drop it in again?

The black line in the parametric EQ window shows the overall frequency response of all the filters instantiated in the block. The colored lines show the individual response of each filter.

Hello JeradL,

Le Thu, 05 Aug 2010 23:14:15 +0200, JeradL

<analog@sgaur.hosted.jivesoftware.com> a écrit:

I am not able to recreate the problem you're showing here. Have you

tried to simply delete the parametric EQ block from your design and drop

it in again?

I tried it with no success

The black line in the parametric EQ window shows the overall frequency

response of all the filters instantiated in the block. The colored lines

show the individual response of each filter.

this works fine **until I modify the low frequency display value** ( on

the upper left corner of the parameter window ) !

I did a complety new simplified project SGBRT5 and the black curve works

as you explain and I expect ( picture SGBRT5A.JPG ) but goes mad if I

lower the display frequency to 19 Hz ( 3 Hz seems to be a limit ? ) and

even if I go back to 20 Hz ( pictures SGBRT5B, C and D ). Closing and

reopening the parametric window with lower limit different from 20 Hz

worsens the effect ! Going back to 20Hz, closing and reopening the window

is ok !!

I see that the (red) curve in the Simulated Response Window of my probe

stays correct all time. If I delete and recreate the EQ all works fine

until I touch this evil diplay parameter !!

Can you confirm this behavior ? Is it a bug ? May be there is a

possibility to lower the displayed frequencies outside the parametric

window or before opening it the first time ?

Thank you for your help.

Kind regards

Peter Greuter

I am getting an error when I try to open the parametric EQ window in your latest project. You have the maximum displayed frequency set to 30000, which is higher than the maximum 22000 that is allowed. I am not sure why the software allowed you to enter that value, but I am not able to view the parametric EQ block in your design while that value is set.

I have built my own projects using exactly the same settings as you and have not seen any problems. All of the filters and overall frequency response in the parametric EQ block display correctly. I would suggest that you lower the maximum frequency displayed. It seems that you're only having problems when you try to extend the displayed frequencies beyond the allowable limits.

I believe that the problem you're seeing has been corrected in the latest builds of SigmaStudio. There is a new beta version available now. You may want to download that to see if the frequency response display errors are no longer appearing for you.

Hello JeradL

Indeed : all my trouble went away with **the latest beta version** : the black curve works like a charm even when I display all the frequencies between 3 and 22000 Hz. And you are right : it is no more possible to increment after 22000 Hz in the upper frequency field.

Thank you very much for your advice and have a nice week-end !

Best regards from Paris

Peter Greuter